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  • HPH389: Air-to-air mini split heat pumps – with Es Tresidder

    HPH389: Air-to-air mini split heat pumps – with Es Tresidder

    Es Tresidder from Highland Passive explains what an air-to-air mini split heat pump is, why he believes it’s a good choice for heating a high performance home and the various pros and cons of going down this route. He also reflects on one of the toughest stages of his retrofit when they took the roof off the existing dwelling and then faced torrential rain.

    Interview with Es Tresidder

    Es Tresidder is a certified Passivhaus Designer with over a decade of experience in low energy buildings. His consultancy Highland Passive helps self-builders and retrofitters create better homes, that are healthy, comfortable and energy efficient. He’s also been working on various projects for John Gilbert Architects over the years, and he’s a regular at House Planning Help as part of our ‘ask the expert‘ team in The Hub.

    Es has been on the podcast before, explaining how he upskilled in DIY during his retrofit project. In this session he’s reflecting on the whole process, including a key challenge he faced with water damage, and he’s going to go into detail about how he heats his home with an air-to-air mini split heat pump.

    Es is a regular in The Hub where he helps answer questions on building physics and retrofit

    Vehicle-to-load allows you to use an electric car’s battery to power external devices

    This podcast was recorded during a power cut and was only possible because Es has an electric car capable of vehicle-to-load, which means that you can plug an adapter in to where you normally plug it in to charge, and then plug a three pin, normal domestic plug into that, and run that into your house. He explains that you can’t power your whole house, but you can take three kilowatts from it, which he was using with three or four extension cables strewn around the house, to power the fridge freezer, the dishwasher, the Wi-Fi, to charge computers and even to make a loaf of bread overnight!

    “…logically, you know that electricity is very, very useful in life, but life just becomes much harder as soon as you don’t have electricity.”

    When Es put the services into the house, he created a service void, which is effectively a pipe that goes through the external wall with an airtight membrane on one side and a windtight membrane on the other. This means he can add new cables into the house and make them airtight easily. He did this when adding solar PV to the roof and now he’s done it again, putting in a permanent extension cable that can connect to the car, ready for the next power cut.

    Home battery systems with ‘island mode’ help you operate independently from the grid during a power cut

    Es explains that domestic inverters shut down when the grid fails, preventing the house from drawing power from solar PV panels during an outage. However, if you have a home battery system you can pay extra so that you can island from the electricity grid, which would happen automatically during a power cut. However, domestic batteries are only around seven to 12 kilowatt hours, so if it was January or February, with little solar power generation, you’d quite quickly go through your battery’s power, even in a Passivhaus. A car battery is much bigger, around 77 kilowatt hours, which would last several days during mid-winter, running heating as well as everything else. Another advantage is that if the power cut lasted much longer, he could just drive into town to a public rapid charger and top the car back up.

    Getting the MVHR back on was a priority because it immediately improves the health and comfort of the home

    Es says the MVHR has a really small energy requirement and is beneficial in lots of ways, so it was the first thing they plugged in. Until that point they had been keeping windows open for ventilation and, with an outdoor temperature of 12-13 degrees, the temperature inside had dropped down to around 17 degrees.

    The existing dwelling before any alterations

    The completed project

    Photography by Alex Trowski, commissioned for a case study in Passive House Plus Issue 50

    The retrofit, extension and remodel has made the whole house work better as a home

    Es’s house was a 1975 timber-frame build of one and a half storeys, where the first floor rooms felt quite pokey. So the strategy was to take the whole first floor off and rebuild it as a one and three-quarter storey house. This may not sound like a big increase, but Es says it gave a lot of extra floor space on the top floor, with enough for an extra bedroom, and an increase in size for the other bedrooms. The floor plan just worked much better.

    The upper floor is a new build Passivhaus, with an I joist timber frame sitting on top of the existing structure, which was quite complicated to do. Downstairs is a retrofit of a 100mm timber frame house, where the plasterboard was taken off and insulation put between the studs. He then added another 40 mm of wood fibre insulation board, an airtightness membrane, and then outside of that is white rendered blockwork. There’s a cavity between the two. As a Passivhaus Designer, Es did all the energy side of things and a lot of the retrofit work himself. The new build was carried out by a local contractor.

    The project involved removing the pitched roof and extending upwards

    Keeping a flat roof dry is incredibly difficult

    This project required the first floor and roof to be removed, which is slightly unusual. When they were looking at the options, one way to keep everything dry was to put up a massive tent over the whole structure, but this would set them back £30,000. The builders, however, were confident that they could keep the water out because they had done this many times before. There was also the fact they would be doing this in May which is statistically the driest time of the year in Fort William. Unfortunately the weather did not play ball and it was an unusually wet month. Es also points out that although the builders take off lots of roofs they probably don’t remove the whole structure leaving effectively a flat roof to keep dry.

    So it just became impossible to protect the structure from the torrential rain. Es had already insulated the ground floor and achieved good airtightness but the rain soaked the floorboards and insulation, forcing him to strip them out and replace everything.

    “You don’t want to install any insulation until the building is watertight.”

    A lot of insulation got waterlogged and had to be replaced

    Sequencing the work differently would have avoided damaging the insulation

    If doing the project again Es would not necessarily pay for the giant waterproof tent but he would sequence things differently. The work downstairs had been done first to ensure structural stability for the new first floor and roof. However once rain had compromised the work, they had to go ahead without the extra racking boards on the walls anyway or the racking strength from the floor. He would therefore consult a structural engineer to look at any structural elements that could be done without involving the insulation.

    The unit inside the house

    An air‑to‑air mini split heat pump is a cost effective way to heat a low energy home

    For Es, a heat pump is an obvious choice over direct electric resistance heating. However, instead of a conventional air‑to‑water heat pump system, Es chose an air‑to‑air mini‑split system. He explains that this is like an air conditioner, which usually pumps heat from inside to outside a building, but can also be used to pump heat from outside to inside a building. They have a similar efficiency to an air-to-water heat pump, but are much cheaper to install, because there’s no need for radiators or a wet system. The mini split has an outdoor unit and an indoor unit, with refrigerant lines between the two. The unit and installation cost was around £1,500 compared to £12 000 for the air‑to‑water system. Es is clear that this system is great for a Passivhaus but wouldn’t work for a normal new build house as it only delivers heat into one room and relies on heat spreading to other rooms.

    The unit outside the house

    Reversible operation provides useful cooling in heatwaves

    Mini‑splits can run in reverse to deliver modest cooling, which has proved handy for Es during a heatwave which coincided with the midge season (when they don’t really want to open any windows) and a large group of friends staying over and thus raising the indoor temperature.

    Sizing the mini split above peak load ensures comfort in cold snaps

    The house’s peak heating demand is around 1.3 kW and by selecting a 2.7 kW mini‑split Es has provided a comfortable margin, which allows the system to cope with occasional freezing cold days without needing supplementary electric heaters. In cold weather he will run the system overnight when electricity is cheaper, so increasing the temperature in the main parts of the house, whilst the bedrooms stay cooler. Once the doors are open the heat can spread through the house. He admits that having his office in his bedroom means occasionally it can be cooler than he would like and so a small electric heater would probably be a good addition.

    Photography by Alex Trowski, commissioned for a case study in Passive House Plus Issue 50

    Locate an air-to-air mini split system in a large open area

    Es explains that the mini split system needs to be in a space big enough to deliver a lot of heat into it, before warming that space to above the set point temperature. A small room would reach that temperature quickly then the system would shut off and so not provide enough heat for the rest of the house. The indoor fan also produces a low hum comparable to a refrigerator, louder than the house’s MVHR, so you need to place it where the noise won’t matter too much. Es stresses that whilst the MVHR supplies fresh air, and recovers heat it only moves a small amount of warm air between rooms. Keeping interior doors open lets the warm air from the mini‑split circulate more effectively.

    Grants favour air-to-water systems, but air-to-air systems may still be cheaper

    Even though Scottish renewable‑heat grants are available for air‑to‑water heat pumps and not for air‑to‑air units, Es feels the air‑to‑air solution may still be cheaper. The grant system also involves a lot of paperwork and restricts you to using MCS certified contractors, who are not necessarily the best. For a Passivhaus going down the air-to-air route also means you keep things simple.

    A standalone hot water pump works alongside the air-to-air system

    Whilst air-to-water heat pumps can also be used to supply hot water, an air-to-air mini split system is just warming the air in the house. So Es has installed a heat pump water heater, which is a 200 litre insulated hot water tank with a small heat pump on top. They are normally ducted to the outside to bring fresh air into the heat pump, the heat pump takes some heat out of that outdoor air, and then it ducts the exhaust air back out. Es has set his up to take heat from the house, which gives some free cooling in the summer and a much faster reheat time in the winter. It’s also easier from an airtightness point of view as it is not ducted to the outside at all. In the winter, the water heat pump is slightly cooling the house, so the mini split has to work a bit harder, but overall, it is still very efficient.  

    Living in the house has been amazing

    The house before Es started had quite serious mould and damp problems. They were always a bit chilly in winter and couldn’t dry things because there was no reliable ventilation, and the house wasn’t warm enough. Now things are completely different.

    “It’s hard to remember how it was before, because it’s just so nice now.”

    The house is warm and comfortable all the time in every room. Es believes it’s almost more impressive in hot weather than it is in cold weather, when you expect it to be warm. Es says that the first summer they moved in, they had two separate weeks of more than 28 degrees as peak temperatures in the afternoon. And in those conditions, the house was at 23 degrees, and it felt like walking into an air-conditioned space. It has really improved the quality of life. The air is clean and just walking outside the house, Es immediately notices if the neighbours oil boiler is running or there’s a coal or wood fire on locally.  He thinks his sense of smell has improved, because he’s used to clean air and the house smells fresh all the time. The best thing isn’t the bills, but it’s the most quantifiable thing. He’s reduced his heating bill by at least 80% while also massively increasing the average temperature of the house.

    “After one full year of monitoring we have spent £175 on heating and hot water for a family of five, which is remarkable.”

    Find out more

    Highland Passive

    Heat Geek

    OpenEnergyMonitor

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  • HPH388: How are building regulations made? – with John Palmer

    HPH388: How are building regulations made? – with John Palmer

    Having spent the last few years working within the Ministry of Housing, Communities and Local Government, John Palmer explains how building regulations are made and what their role is within the construction industry.

    Interview with John Palmer

    In 2012, having served as an engineer in the Royal Navy for 16 years, John Palmer pivoted into the construction sector. Over time he gained his Passivhaus credentials, built a high performance home and also spoke to us about the impact of setting an energy target. He then joined the Passivhaus Trust and was trying to lobby the government to do great things for energy efficiency and housing when an opportunity came up in the Ministry of Housing, Communities and Local Government. He moved into a policy position there four years ago, looking at the Future Homes Standard and Energy Performance Certificates. John has recently taken a secondment to work with the Building Safety Regulator on some of the processing of Building Control applications.

    British building regulations date back to the Great Fire of London

    The origins of building regulations can be traced back to the Great Fire of London in 1666, which resulted in banning timber in the external construction of homes in London. More recently, the building regulations, became not just for fire and structure, but for many other aspects like energy efficiency and moisture, so that there are now 18 parts to the UK Building Regulations.

    Each regulation will require a certain outcome to be achieved

    John explains that the Building Regulations are primarily outcome-based regulations, which means that they don’t set prescriptive requirements for how things should be built. For example, Part B relates to Fire, with outcomes to build things that don’t spread fire to other buildings, and that can resist fire for long enough for people to get out. This could be met in a variety of ways.

    The Building Regulations set minimum standards for life safety

    The primary intent of the Building Regulations is to set minimum standards for life safety and that’s where most of the regulations are targeted. John explains that it’s not just about structural collapse and fire, which are obvious threats to life safety, but also longer-term threats such as poor internal air quality and moisture levels within buildings.

    Over the years, additional regulations have been added that go beyond this. For example, broadband services and electrical vehicle charging have their own part of the regulations.

    Events often drive significant changes to the regulations

    The Grenfell Tower tragedy in 2017 had a huge impact upon building safety in the UK, notably prohibiting combustible materials from being used in the external walls of buildings more than 80 metres high.

    Whenever government decides to bring in a change to the regulations, there is a lengthy process involved to work out what the impact of that change might be.

    “Is this going to do what we would like it to do? Is it going to be enough? Are people going to try and circumvent it?”

    There can also be unintended consequences to consider.

    “What else would people use? What are the non-combustible materials? Are there enough of them in the supply chain? What does that mean for the quality of design or structural strength?”

    All these second order effects need to be considered during the policy-making process to ensure the unintended consequences have been explored, and any risks are accepted or understood.

    John Palmer giving a keynote speech at the ASBP Healthy Buildings Conference

    Policy changes stem from the government of the day

    Any changes to the Building Regulations will be initiated by the government of the day, who will ask the civil service for an assessment of the impacts. This will include the second order effects that might occur from a change to the regulations, such as to supply chains and labour markets. Ministers will be looking at how they will balance the impact of the proposed change to the regulations versus other competing government priorities. In some cases, a minor change might be relatively straightforward, with little or no impact on anything else, in which case it would be implemented. Other more significant changes might have bigger impacts on the cost, complexity or material supply chains of new homes. Government ministers will take a measured decision as to whether to press ahead, postpone it or do a lesser version of the change in order to lower the impact. It becomes a proportionality and judgement call for the government of the day at that point.

    Policy‑making is a multi‑stage, consultative process

    John shares an example of how a regulation might be created and the process it would need to go through. So, it might be proposed that we should paint all our houses pink in the future! This would then be assigned to a relevant team in the civil service, and they would look at how it might work and form some options of how it might be achieved. Building regulations might be one of the options. They’ll look at the potential benefits of pink homes, they will put that to ministers, and create a consultation, because normally there has to be input from the public or a stakeholder view for any proposed policy change. The consultation will have to get ministerial approval and cross government approval. It then gets published and runs for a minimum of three months, at which point it will be evaluated. The results may lead to more questions that need answering and so that might require further work. The options then go to ministers, who may ask further questions or want different options. If an option is approved that requires a change to the regulations themselves, not just the guidance, then a statutory instrument needs to be drafted by lawyers, checked several times and then time found for it to be laid in Parliament. In other words, it’s not a trivial process to update the regulations and can take anywhere between 12 months to two years to put in place.

    Other mechanisms could achieve the same outcome

    The other option is to encourage the desired outcome. So, in our example there could be an advisory that encourages all homes to be painted pink, and there might be a scheme whereby discounted rates on pink paint from a local retailer has been arranged. This whole approach could be put in place in two or three months.

    “The carrot encouragement, optional, discretionary type approach to getting things into the built environment is always much quicker than the stick approach of actually going through and making changes to the regulations.”

    Approved Documents provide statutory guidance on how to meet the regulations

    Accompanying the Building Regulations is a set of statutory guidance, known as the Approved Documents. John explains that Part A of the UK Building Regulations, which is a statute in law, has an accompanying Approved Document A, which is the statutory guidance that sets out how that part of the building regulations may be complied with in typical situations. That means that someone designing a building can look at that Approved Document and know that there is a clear path to compliance. John says that if you are doing something slightly unusual, say an innovation, that might not be covered by the Approved Documents, then it is the building regulation itself which must be complied with.

    Regulations will always evolve

    In an ideal world, all regulation is necessary, all regulation is minimal, and all regulation is proportionate. These are the tests that government applies when introducing new regulations. However, things do change over time and regulations which were previously proportionate and made perfect sense, may no longer do so. This means there will always need to be a review and update of the regulations.

    Regulation is nothing without enforcement

    Part of creating a regulation involves working out how the government or the relevant regulator will know if that regulation has been complied with. Also they must consider what action to take if the regulation is breached.

    “As part of the policy process, you would define what the sanctions would be for organisations or individuals that didn’t comply, which might include fines or coming off registers.”

    Building Control is the main mechanism in place to ensure that people are compliant with the building regulations.

    New regulations may have a long lead in time

    Where the impact analysis has been sufficiently confident that the regulation is going to work, it’s not going to cost a fortune or result in supply chains collapsing, it can be put in place in fairly easily. Where it’s less clear-cut, different approaches can be taken. One of the primary routes is to give a long lead in time to allow the industry to plan and adapt. This way it’s also easier to address unintended consequences if they arise.

    John tells us it can be more difficult for the government to run small pilot projects as there is a tendency for people to think a proposal is definitely going to happen, which can result in unintended consequences for segments of the industry.

    Incentive schemes can also encourage behaviours

    Incentive schemes are another mechanism that government uses to encourage certain behaviours. They’re not necessarily regulated in the same way as by their very nature, they’re never going to be enduring. They are used to encourage either innovation in technology, market shifts or consumer behaviour, with solar panels being a good example. When solar panels first came in, they were prohibitively expensive, so incentive schemes mitigated against the high costs, and made them more attractive to homeowners. When the price of solar panels dropped to affordable levels, where payback periods without incentives still made financial sense, the scheme had done its job and that money could be better targeted elsewhere.

    Digital tools and automation are the future of compliance

    Currently, implementation of the Building Regulations relies on individuals becoming experts in compliance, which may not be the optimal way of doing it. John tells us that an Approved Document review panel has just been set up to look at how the documents are formed, communicated and relate to each other.

    “For example, is there a single definition of a dwelling that’s used across all the Approved Documents, or are certain words used in different ways in different parts?”

    John says this does happen, so communicating them more effectively and setting them out in a different way might be an option. Digital processes may also be embraced more in the future, perhaps becoming more integrated into CAD design systems.

    “Where regulations talk about heights, clearances, etc. could it be possible to have a level of automation? Or maybe a red, amber, green indication that you are compliant with the Building Regulations? Those kinds of things could make a big difference and create a better starting point for a designer to feel confident they’ve designed something in accordance with the building regulations.”

    Sometimes you may need specialist input to check you are compliant with the Building Regulations

    When building your own home or having your own home built, you can use either the Local Authority Building Control or a registered Building Control private provider. As part of your project, you will submit evidence to demonstrate that you’re compliant with the Building Regulations. This will include documents and drawings showing the structure of the build, fire safety, etc. For a typical self-builder, this will be quite specialist information that will require technical input. For John when building his own home, he was keen to have an input over the design materials and felt qualified to have a view on those. However, when it came to other parts of the Building Regulations, such as the structure and fire safety he knew he needed to bring in expertise.

    “That specialist input may sit with your architect or designer along with structural engineers, possibly fire engineers and energy assessors when required.”

    New building standards apply to some but not all aspects of retrofit

    John outlines how new build standards, don’t necessarily apply in their entirety to retrofits, because you’re starting with something already built. For example, energy performance will be looked at differently in a retrofit, where you can’t necessarily decide the form factor, the size of the windows or amount of glazing.

    There is also a basic principle of non-worsening in the Building Regulations that applies to retrofits. If you’re redoing an entire wall, you might need to bring that up to a required standard for thermal performance, whilst other aspects of the Building Regulations might not apply. You don’t necessarily have to make your refurbished building as accessible as a new building, but you do need to make sure that it doesn’t get less accessible, which is the non-worsening principle. Your Building Control body should be able to advise on exactly what level you need to reach in certain areas and whether other things would be subject to non-worsening, in which case you can leave them as they are.

    There’s likely to be a more coherent approach to housing as a system

    John concludes by noting that many different pieces of legislation have grown up organically over time, which drive outcomes in the housing sector and so it is a complex area. He thinks that the regulatory landscape will start to evolve to a more coherent approach towards housing as a system. This could go all the way from deciding what you’re going to build, planning, designing, building regulations, and once built to its occupation. All those regulatory regimes could work together a bit more seamlessly, and a bit more effectively.

    “So that the end result – which is people living in high quality, safe, decent homes, beautiful homes that you know are a pleasure to live in – becomes more the norm.”

    Find out more

    Ministry of Housing, Communities & Local Government

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  • HPH387: How do you make a Victorian terrace home more comfortable? – with Will South

    HPH387: How do you make a Victorian terrace home more comfortable? – with Will South

    Will South from Etude takes us step-by-step through the retrofit of his Victorian terrace house in Brighton, which has improved the health, comfort and energy efficiency of the property.

    Interview with Will South

    Will is a mechanical engineer, working at Etude to make buildings better through reducing energy consumption and carbon emissions, an approach he has carried over to all the places he’s lived. With his most recent move he had in mind a retrofit project right from the start. He wanted to be in the middle of Brighton, close to the railway station and the coast, in a modest sized home. So he chose a Victorian terrace house, originally a two-up two-down that he could retrofit to the level that would be right for the building.

    Many period properties have common traits

    Will’s house is a classic Victorian terrace design, where there is space for you to take off shoes and coats just through the front door, the stairs are in front of you, then there’s the living area on one side and a kitchen all the way through at the back. Upstairs, there are two bedrooms and a bathroom. Will describes it as a simple layout with a nice flow and high ceilings, even upstairs, which is more unusual.

    Deciding how deep to go with your retrofit is a personal choice

    A big part of Will’s day job is working on Passivhaus projects, but here there was a question around the right level of retrofit for this type of property.

    This project has also made him realise that maybe not all homes need to have as deep a retrofit as he used to think, and that heat pumps are more than capable of heating the majority of homes with few changes. However, he knew he wanted to take it further and make the house as comfortable as it could be. With his experience in ventilation systems, glazing specifications, insulation, etc. nothing was off the table.

    “We’ve done everything: walls, roofs, floor, new ventilation system, new windows, but a lot of it is as an experiment to show how it could be done.”

    Watch an EnerPHit retrofit of this Victorian home in The Hub.

    Decarbonise your heating by moving to a heat pump

    One key move Will wanted to implement to lower his carbon emissions was to switch from a gas boiler to a heat pump. For most homes, some fabric measures may be needed, often topping up loft insulation, improving windows and upgrading radiators. Anything after that will continue to improve comfort levels, reduce bills and increase resilience for the future.

    Create an overall plan for your retrofit

    Will started with his dream end point, irrespective of budget, to come up with an overall plan for the retrofit. For example he has not installed solar PV as part of the project but he has made allowances for it as a future addition.

    With a solid retrofit plan, he then examined the priorities. There was leak in the roof and a rear extension, where the floor and the roof were in a sorry state. Generally, starting with the roof is a good strategy, which for him meant redoing a parapet then making sure the party firewalls and the chimneys were in a good state before he did anything else, so that the building had a good chance to stay dry.

    Having a good ventilation strategy is essential on a retrofit project

    Will tells us that although it took a long time he ended up doing everything in almost one go. If you have to do a phased retrofit, you need to make sure that the building is left in a good working state at the end of each stage. The main risk is around ventilation and managing moisture in the building, and you need to be careful you don’t seal up the building or insulate it in one part without dealing with the ventilation. A ventilation strategy is often a priority and if the end goal is a mechanical system, then get that in early, so you’re already managing the moisture levels.

    SketchUp was used to create drawings for the project

    As a consultant Will knew what was needed but he wasn’t used to doing the drawings himself, so that was a bit of a challenge. He used SketchUp to create a model of the house, including drawings for the existing building and the proposed building. Being in a conservation area, planning permission was needed for replacing windows at the back of the house, and altering the roof-scape slightly to fit the heat pump at the rear, which led to more drawings for the planners. In the end he made a full set of drawings to help him work out what he was going to do and allow him to communicate easily with the contractor.

    Will imagines that in the future there will be templates for every building type, that you would alter to reflect your own situation. There’s already a good website called retrofit.support, which has a pattern book of details that give you a place to start.

    Create a detailed cost plan

    Will paid a cost consultant who specialises in housing to provide him with a full cost plan. This gave him a long list of everything needed, with a starting point for all the prices, giving a good feel for what it would cost if he did everything. This service cost around £400 but was invaluable.

    The costs for construction broadly came in as expected. He imagined that there might be a big cost differential between materials but in actual fact he was dealing with such small areas that the cost was all in the labour.

    Budgeting for the internal finishes was much more difficult as costs varied dramatically, particularly for bathrooms and kitchens. So unless you have an example of the product that you want to use, it can be hard to budget accurately for this stage.

    Different insulation strategies have been used around the house

    Will explains that even though it’s a small building a variety of strategies have been needed to insulate the roof, walls and floors. Initially they planned to live in the house while the retrofit took place. The first phase was going to be the rear return, with the kitchen and the bathroom. The kitchen ceiling was falling in and the bathroom ceiling looked worrying, so both needed attention.

    The building has all sorts of roof types, which is not ideal. There is a small parapet at the front which has got insulation between the rafters and a lead roof. Then there’s the main loft which has mineral wool insulation, the rear return which has Larsen trusses, filled with insulation in the pitch, and a small flat section of fibreglass roof which has got the heat pump on it.

    “Generally, starting with the roof is a good strategy. An old fashioned building has a good hat and good boots.”

    Planning restrictions also had an impact on the insulation strategy

    Being in a conservation area an internal wall insulation strategy was adopted at the front of the building, using 80mm wood fibre board. There is a bonding coat underneath, made by Baumit, which helped create a flat base for the boards to go on to and added an extra 10-20mm of insulation.  

    At the rear of the property they were allowed to insulate externally and have used cork, which was chosen because it deals with moisture better than some other products. The external wall insulation is taken below ground to the foundation with EPS.

    The floor became a bigger project than originally planned

    While Victorian properties are highly desirable today, when they were built they were thrown up quickly and cheaply so there were a few surprises lurking. When they took up the floor, they found slim 3-inch joists sitting on continuous bungaroosh, which was just piled up chalk. As they were able to move out of the house for a few weeks they could tackle the floor in a more significant way.

    It involved taking out all the timber and the dwarf walls, scraping back the chalky base to create the space needed for the floor build-up. EPS was directly put onto the sand blinding, then a plastic DPM, and finally a concrete screed with underfloor heating. It’s a simple build-up as there’s no structure sitting on it. Will would have liked to have reused the original floorboards on top of the screed but was advised against it.

    The sash windows have been improved

    While Will had more freedom at the back of the house, where he installed some triple-glazed units, at the front of the house there were restrictions. He also did not want to get rid of the beautiful period sash windows. So he has replaced the sliding part of the sash and put in vacuum glazing. The boxes are original although he has added a draught strip to improve airtightness. He’s used a foam filled rubber draught strip, a type more often used on a casement window, which is more robust and gives better airtightness, but it makes the windows a bit stiffer. As all the windows are wooden, they will need maintenance and Will suggests to always repaint them just before they look like they need painting!

    Having a continuous airtightness layer was easier said than done

    The strategy at the beginning was to identify where the airtightness line would be for each part of the construction. Will realised that they would be able to achieve it for some parts, but in other areas they wouldn’t be able to get into places to create an air barrier. He estimates that he got around 75% of the way with airtightness and to get any further would probably have meant gutting the whole house and starting again. The intermediate floor and all the internal walls stayed where they were, but the external wall finishes were removed allowing for bonding of the insulation, creating continuous runs to tie into the next airtightness material and into the windows. The damp proof membrane underneath the screed on the ground floor comes up the inside of the wall and is taped on there. In the loft Will put a membrane over the top of the joists, cut it around all the trusses, taped it and then put the loft insulation on top of it. It was very difficult to tie it into the top of the walls right into the eaves where access was limited. The eaves were extended very slightly at the back of the house to accommodate the external wall insulation. This meant the last two tiles were off for a time and Will used the opportunity to do more taping. His approach was to use membranes only where there was timber, and then everywhere else to use a wet lime product.

    Before the sash windows were replaced, Will got an air permeability of 2.1 which is three air changes per hour at 50 Pascals, which he was pleased with and was in fact the number he’d put in his PHPP model. He hopes it will have improved and is going to get another air pressure test and more thermography in the winter.

    MVHR can usually be integrated seamlessly into an existing home

    Installing mechanical ventilation with heat recovery can really improve the indoor air quality in an existing dwelling. It manages moisture in the home, allowing you to do things like cook or dry washing without consequences. And Will believes that there is always a way of designing a system into an existing home and figuring out the duct runs, etc. It just takes careful planning.

    The benefits of MVHR are noticeable even in a leaky home

    Even if the airtightness has not been addressed fully Will feels that installing MVHR will improve the ventilation in a house and because it has 90% heat recovery it will give some energy saving no matter how efficient your building is. If you then improve insulation and airtightness you will continue to see benefits.

    A heat pump is a good choice for a low energy home

    When they bought the house it had a 10-year-old combi boiler, which they could have used for a bit longer, but Will was keen to switch to a heat pump heating system. So when redoing the bathroom he took the opportunity to put a new hot water cylinder where the boiler was, because all the pipe runs link to that point. An extra motivation to get off gas was the massive gas meter that was located in the entrance hallway. He paid extra to get this disconnected and removed.

    In Will’s experience it was difficult to buy the heat pump and difficult to get it installed, a view that other people have also expressed. At the time, it was also difficult to find somebody qualified to install heat pumps. In the end, his builder’s plumber carried out the work, and used it to upskill and get his MCS qualification, which was really positive. On the negative side, he hadn’t known they didn’t have MCS and so he was not able to get the boiler upgrade grant.

    He had assumed that the heat pump manufacturers would know what was needed for a small home, so hadn’t looked into the detail himself. That was a mistake and the whole process got complicated very quickly. They’d assumed he wanted thermostats in lots of different places, and that the radiators and underfloor heating circuit were on different zones. Will ended up having to change things afterwards, which was frustrating. The other eye opener was just how much equipment you end up with inside the house. He had thought about a cylinder, but with unvented cylinders you also have an expansion vessel for the heating, an expansion vessel for the hot water. Then there are two control boxes, two zone valves and they wanted to put in a buffer vessel as well. It really started adding up, with a lot to fit in a small area. He recommends buying a hot water cylinder with a built-in expansion vessel, which is a bit more expensive but saves on space.

    Will’s energy consumption has gone down significantly

    The average temperature within the house has increased to a constant 20 degrees, which is where Will wants it to be. Gas consumption has gone from 158 kilowatt hours per metre squared per year, which was quite high, to zero.

    This has however been replaced with electric heating, with electricity use now around 40 kilowatt hours per metre squared per year. This went up about 20% after the switch over to electric heating, so a much smaller uplift than the reduction in gas. By Will’s calculations his carbon emissions are down by 85%, which is significant. If solar PV was added at a later date they could be net zero.

    Some of this is about how they live, with just two people in the house they don’t have huge consumption and are out a lot of the time. In financial terms their energy costs have more than halved, reducing from £2,500 a year to about £1000 a year.

    Sticking to a budget is tricky!

    Will sees a budget as a good tool to manage costs although he realises this isn’t necessarily what you’re going to spend. Therefore he put aside a significant contingency. For him this takes away the worry about money, which can so often cause problems.

    Buying a smaller house in the first place and securing a bigger mortgage so as to free up the cash was also sensible. They had an inheritance and some savings, which essentially has all been spent on the house. It has come in at around £150,000, but this figure includes a new kitchen, new bathroom, new flooring and a lot of extras.

    Replacing the suspended floor was a gamechanger

    Amongst the takeaways from the project Will feels the hard work and disruption of putting in a solid floor with insulation underneath has really paid dividends. So if you have enough space to play with then this is something Will would definitely do again as it’s made it draught-free and always comfortable to walk upon.

    The installation of the heat pump relied heavily on the plumber

    Will was surprised that even though they had a Vaillant heat pump and used their designs, a lot still rested on the plumber. If he was doing it again Will would take more of it under his control.

    Airtightness is often about doing the best you can

    Will thinks he did a really good job on airtightness, but reflects upon the fact that there is always more that could be done. If he were to do it again he would use more traditional wet materials like lime-based plasters for airtightness when dealing with crumbly brickwork.

    The house is now comfortable all year round

    When they bought the house the structure was worrying with a bendy beam, ceilings falling down and it was very damp, with slugs behind the kitchen cabinets. During the winter they were just heating whichever room they were in and downstairs they were always aware of draughts from under the floor. There is none of that now, it feels homely and is a constant 20 degrees throughout the house all year round.

    Find out more

    Etude

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  • HPH386: The potential of mycelium-based composites – with Joshua English

    HPH386: The potential of mycelium-based composites – with Joshua English

    Joshua English, co-founder of Okom wrks labs shares his journey into the creation of a mycelium-based composite material, which has structural and load-bearing properties.

    Interview with Joshua English

    Joshua English, co-founder of Okom wrks labs describes himself as a jack of all trades with a lifelong obsession with fungi. Although he did an arts degree, he realised he loved working with numbers and so spent his early professional life in database programming. After 18 years doing data analysis and data visualisations for healthcare he started to miss the physical world. He then took a degree in Interior Architecture and Design, with an emphasis on industrial design which led to a hyper focus on materiality. A long-time carpenter, with a love of metal and concrete and the knowledge that those materials were not great for the environment, he wanted to try to find the most sustainable way to build things. When a friend introduced him to mycelium-based composites about six years ago, he took a deep dive into the subject.

    Could he make a chair using mycelium-based composites that people could sit on?

    In his research he came across pictures of chairs made from mycelium-based composites, but nobody was sitting on them. Could he be the first designer to make a chair that a human could sit upon? He spent six months gathering information on the technology with a plan to spend two years researching how to make mycelium-based composites stronger. He ended up finding a solution much quicker through a random application of materials left over from his first set of experiments. He then had to reverse engineer from this “mistake” to work out what had happened. It took a few years to patent this process and they are now looking to patent the material itself.

    Mycelium are fungi and not to be confused with plants

    Mycelium is fungi, which is in its own kingdom and not to be confused with the plant kingdom. Joshua explains that where animals engulf their food and plants photosynthesize, fungi absorb their food, so their whole lifestyle is centred around surface area. We think of mushrooms as fungi, but they are just the fruiting body, the mycelium is by far the vast majority of the organism. He compares it to an ant colony, where the individual ants are like the hyphal strands of the mycelium. A mycelium will have billions of hyphae that branch out to explore their environment. They provide a large surface area and exude enzymes to absorb their preferred food source. To do this the hyphal strands need to be incredibly strong, durable, and multi-use as well. Joshua is exploiting the capability of the fungus to create an adhesive to use as part of the matrix of a composite material. Not all fungi have the capabilities to create strong mycelium-based composites, and so far, mycologists have found that fungi that grow on trees are particularly well suited for this.

    This technology is still in its infancy

    The technology goes back to the early 2000s, but it has grown and developed in the last 25 years. Philip Ross, an art major at Stanford and a lifelong mycophile started to develop processes to make things out of mycelial colonies about 20 years ago. He then used mycelium blocks to create striking artworks and published his findings, which people started to notice. Some engineering students in New York, then developed a business model to use this technology to make a foam packaging replacement. They tried to commercialise it about 13-15 years ago. When researchers started to look at the key qualities of the mycelium-based materials they were impressed with its fire resistance and sound attenuation, but it was not so good structurally or when it came to water absorption. This led to them being relegated to insulating panels or decorative wall sound mitigation panels.

    “And then, you have a guy like me who makes a mistake in the lab and then finds this way to make what seemed to me to be structurally sound materials.”

    Turning it into a business is a huge challenge

    Joshua believes that a 5 -10 year time frame is needed to go from the research phase to a commercial product. In his experience Venture Capital investors want more of a 2 year turnaround, so there is a mismatch here that needs to be overcome. Because it’s such a new technology there is a lot of siloing happening along with a push to early commercialisation. There is also a big rush to patent the materials, because you don’t want to be overtaken, but this has all led to a stifling of the technology and people making wild claims. Joshua is clear that any claims need to be backed up with data and currently there are no standards for how we measure and create these things. Joshua thinks that for this technology to move forward governments need to subsidise it and universities need to continue the research. It needs targeted attention and standardisation of methods, but none of this is going to happen without funding. Joshua believes the capabilities for mycelium composites are endless, as endless as the kingdom of fungi.

    The mycelium-based composites are grown in the lab

    Joshua explains that you need at least a food grade level of facility to grow the fungal starter culture, very different to a standard sawmill making SIPs. But one of the amazing things about this technology is you can start from a single fungal spore and grow enough material in about 90 days for several houses. During the process, the spore starts in a petri dish, and you grow it, adding a bit of material at a time. You can increase the amount of material you add as it builds up, whilst making sure the fungus isn’t getting too old, because its life cycle can be rapid. Joshua grows the material in the open air and doesn’t use rigid moulds. A remarkable part of the process is that it takes five days to grow, whether it’s one metre or ten metres, it’s the same amount of time. During that time, it fully colonises the substrate and forms a fungal skin around the outside of the material, which is tough and durable. At the end of the process, you dry it, to kill the fungus, as you don’t want the fungus to continue to digest the material. It is the drying process that gives it the rigidity and strength.

    The Hy-Fi tower

    Experimental projects demonstrate potential for the future

    Joshua completed a non-structural project in New York City two years ago using their mycelium-based composites. The second half of that project was to include the manufacturing of chairs, but difficulties in finding the right facilities to dry the material brought things to a halt. The Hy-Fi tower at PS1 in New York City is a well known example of using mycelium bricks in a large structure. However, the tower was built of timber and the bricks are just infill. A man in Ohio has used edible mushroom mycelium blocks, compressed at a 20:1 ratio to make strong materials. Joshua is trying to develop a different process, which tests how far the fungus can go itself, so not using any industrial compression to bring strength. He is also currently limited in the size he can make, at 3m long by 300mm wide.

    Okom wrks labs could also look at creating a two by four wood replacement product but at this stage it would not be as strong as wood. However, they are finding that if they grow several parts together, at the same time and cross layer them, they can build an incredibly strong 2 feet by 2 feet SIP wall section. In their trial seven parts were all adhered together by the mycelium itself. There was no glue involved and although they didn’t get to do a compression test it did seem like there was a synergistic effect by growing them together in this way. There are more collaborations brewing and the potential for space technologies for drying that would make it possible for them to restart building SIP wall sections.

    Working at full scale they could compete with standard SIP wall panels

    Very early on Chris Magwood suggested concentrating on structural insulated panels (SIPs) and Joshua believes that if they could work at full scale, they could produce mycelium-based composite SIPs at a competitive price. Over time, they could make that difference even greater.

    Mycelium-based composites are already being used outside construction

    Mogu in Italy has been creating decorative sound attenuating wall panels for a long time now, which has kept the material in the zeitgeist. There have been several attempts at creating businesses with foam packaging, but it’s been rather difficult to commercialise the products overall. Le Corbusier regarded chairs as small pieces of architecture and as Joshua is also infatuated with chair design, he thinks a fully mycelium-based composite chair could be the way to show people what is possible. It would show the industry that it can be done commercially, and consumers that you can put these things in your house. They’re not going to grow weird things off the sides, and they will have some heirloom quality to them!

    It is healthy for people with allergies to mushrooms

    In Joshua’s process the fungus is killed at a certain point and never reaches the fruiting body stage, which means spores are not produced. It’s usually the spores that people have sensitivities to, so it’s therefore completely healthy. The other issue is that most mycelium-based composites are incredibly hygroscopic, which means they will take up a lot of water. Other moulds or anything else, could start to colonise the material in a wet state, so you need to be able to stave off that moisture. This would be about protecting it from the elements, like you do with timber, so you would then have a system with longevity. Joshua admits its early days and hypothetical, but from his own research he thinks it is doable, and it is safe.

    He explains that whilst foam-like mycelium-based composites typically have a water uptake of 200 to 300%, their material is far more dense, with a water uptake of around 25 to 45%. That’s a big leap in the right direction with more improvements possible through improving the fungal skin or adding natural products like beeswax. His goal is to avoid any kind of petroleum based products, if possible, but has accepted that using an epoxy resin covering may be a good way to get things started.  

    Hemp is the Joshua’s preferred substrate for growing the mycelium

    Joshua is developing a composite material, which we might compare to the first earth bricks that included straw to add strength to the mud. He is using hemp as the substrate for the mycelium to grow on as it is a strong material and is “tasty” to the fungus they’re using. The fungus serves as an adhesive that binds everything together, so you’re using these two different materials to create something like a brick. He then adds in the textile reinforcement phase that provides even more strength and improves the compressive strength by orders of magnitude over the foam-like materials and other types of mycelium-based composites. That textile reinforcement phase is notoriously difficult as it needs to be clean enough to grow without it getting contaminated before the end of the grow process.

    We need to re-imagine how we use materials

    Even though Joshua’s data is showing increased strength in the material it is still only just over one megapascal in compressive strength. This is not great from an engineer’s perspective, so can we think differently about how we build? He is thinking about modular building rather than lots of concrete and brute strength. Instead use geometry and genius engineering to build lighter, stronger structures. Anything that makes steel lighter and stronger from a geometry standpoint, would also work with their material. There is also work to optimise the way that the fungus grows and possibly some genetic changes to the fungus that would enhance certain qualities. Machine learning can help with this process as there are so many variables to consider. People are now starting of pool resources, with Phil Ross, setting up a nonprofit, called Open Fung. This is to create baselines for researchers, so people are not starting from scratch each time and can hopefully go further and faster on the engineering side.

    The potential applications are as diverse as the kingdom of fungi

    Joshua believes that the potential applications for mycelium-based composites are as diverse as the kingdom of fungi, but the material needs to match the job it’s meant to do whether that’s in industrial design or architecture. It’s also important not to oversell the capabilities. Whilst patenting is important to gain investment, there is a need for more collaboration in the field, and that is Joshua’s request to the mycologists and engineers currently exploring these ideas.

    “I think the future is wide open as we are at the nascent stages of understanding how fungal mycelium-based composites come together.”

    Find out more

    Okom wrks labs

    Follow Joshua English on LinkedIn

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  • HPH385: A stunning contemporary home on a sloping site – with Kirsty Maguire

    HPH385: A stunning contemporary home on a sloping site – with Kirsty Maguire

    Award-winning architect Kirsty Maguire shares her experience of designing and building her own Passivhaus on a challenging sloping site in Newport-on-Tay, Scotland.

    Interview with Kirsty Maguire

    Kirsty Maguire runs an architectural practice and consultancy in Scotland, that blends good design with environmental responsibility, to create buildings that people love. One of her clients used the phrase ‘dream catching’ to describe the process of working with Kirsty, who helps people explore what’s important to them and then turns their dreams into reality. Kirsty does this on all her projects, including her own and feels that building a house can be an enjoyable process. She remembers as an architectural student wanting to create a space for herself, to be part of that world and have that experience. It took over 20 years for her to pinpoint where she wanted to live, find a suitable plot and have the funds available to put this into practice. Here she shares her journey and experience of building her own home.

    Kirsty has also featured on the podcast before, first helping Ben develop ideas for his own house build and then explaining how to incorporate reuse into a project using The Seed as an example.

    Accessing a number of plot opportunities is part of the process

    The idea of building her own home was there in the background for a long time before she really started looking at sites. Her grandmother’s garden, which had an outbuilding that could be replaced, was her first serious consideration, but the timing was not right for her to do the project. However, the thought process she went through, developing her ideas there, became a stepping stone in the right direction.

    When Kirsty is working with clients who don’t already have land, she will help them look at different plots to clarify what they want, what they need and what’s most important to them. Thinking about the future is also important, we don’t know what the future will bring, so having some flexibility is ideal.  

    Get to know what your plot priorities are

    As time went by, Kirsty set up her own practice, went on some adventures, and then got a bit more serious about plot hunting. Some plots came up in Newport-on-Tay, where she was living, but although she visited them and did sketches none of them really floated her boat. But she could identify what was important to her in this location; she had to be able to take advantage of the stunning views, be able to walk to the shops, be part of a community where she didn’t have to drive everywhere. Other people will have different priorities in their plot finding, so it’s knowing what’s right for them.

    Eventually Kirsty saw an advert for the plot where she now lives when she was travelling on a 10-month sabbatical. When she came back, she realised it was a great spot, a really challenging site, steeply sloping, north facing site, amazing views, but it turned out someone else had bought it. She was disappointed, which was really telling, but it came back on the market and she managed to buy the plot.

    A site with a lot of constraints can become a positive

    Kirsty describes it as a tricky site with strict planning restrictions, which limited the overall size of the house, the direction of the build, number of bedrooms and amount of parking. There was also an existing planning consent for a dreadful building all of which put other people off the site and worked in her favour.

    It was a garden when she purchased it, but Kirsty believes it was always seen as a building plot, with the house next door maybe having bought two plots, but never getting round to building on this one.

    The main challenge was the topography, as it’s a narrow site on an extremely steep slope. There is a three-storey level difference between the front and the back of the house. Properties on either side restricted the placement of windows and she needed to ensure the right to light as well as making sure she wasn’t overlooking the other properties. From a Passivhaus point of view, it’s north facing, which is a challenge and most of the views are to the north.

    In Kirsty’s experience once a site has planning permission it is much easier to adjust the details of the building, if you keep within the parameters of the local plan. Kirsty took all the restrictions that had been imposed on the site along with the physical nature of the site itself and used them creatively to create the shape of the house.

    A lot of the core decisions fell into place

    Kirsty knew she wanted it to be a Passivhaus using eco materials, so from that point of view, some of the design decisions were already made. As timber frame building is traditional in Scotland, this was also an obvious route.

    ‘Upside down’ living is a good fit for a sloping site

    Kirsty describes her home as an upside-down building, with an open plan, living, dining, kitchen area upstairs. This has a partial separating wall with holes in it, so that you can sit at the dining table in the south facing sunshine next to the garden and also see the views all the way to Dundee. It’s a two storey, rectangular box with a pitched roof, but the ridge of the roof runs front to back, which is the opposite direction to what you might expect. There is then a box on the side, to accommodate the stairs, bathroom and utility.  From the street you see the gable end of the building, with the ground floor of the building already a storey up above the street, and then it’s two storeys up above that to the ridge. The living space is a tall, generous space, where you could potentially add a mezzanine, but Kirsty doesn’t need any more space.

    Thinking about privacy is also part of the window design

    Kirsty knew that she wanted a big window to the north to enjoy the views and some rooflights to get east and west sunlight into the building to make sure it was light and bright. But, as well as ensuring that she wouldn’t be overlooking other people, she didn’t want them to be overlooking her. She therefore did lots of sight line analysis, which resulted in the big picture window in the living room being raised by 400mm. Architecturally, you might have put in a floor to ceiling window, but having the raised cill gives a huge amount of privacy. People walking along the street, or even in the house opposite, can’t see in and likewise, when Kirsty is sitting on her sofa, she can’t see out.

    Talk to your neighbours to get their support

    Kirsty went round to her neighbours to make sure they knew what was happening and that resulted in lots of letters of support for the building. It’s important to acknowledge that you will be changing people’s local area and most of us don’t like change. If we feel included in the process, we tend to be more comfortable with it.

    The people opposite had built their own house and Kirsty’s house was going to slightly reduce their access to sunlight because of the steep slope, but they were positive because she had thought of them and worked out how to minimise the impact on them. She also feels lucky because the people around her are really friendly.

    Variety in the neighbourhood is often a good sign for a self build

    Kirsty thought a lot about how the cladding of the building would fit into her neighbourhood. There is an eclectic mix, with Victorian buildings, a 1990s period piece opposite, a small brown bungalow next door and some lovely new builds in the village. So she ended up incorporating motifs from some of the buildings around, the big picture window is echoed in the building next door and some of the Victorian buildings across the street, as is the relationship, with the pitched gable roof.

    Some features of the house were not optimal for achieving Passivhaus

    Kirsty explains that some of the constraints led to architectural features that are not optimal in terms of Passivhaus. For example, there are rooflights because she couldn’t have many windows in the walls along the length of the building. Also the desire for a big open space with a cathedral ceiling creates extra volume to heat. All this means is that the insulation must be slightly thicker to compensate.

    The form factor is around four, which is similar to many of the detached buildings that Kirtsy works on. For the Passivhaus certification Kirsty used heat load rather than heat demand. The heat demand is calculated at around 20 kilowatt hours/m² per annum, whereas the heat load is 10 kilowatt hours/m². Her actual energy use is more like 13 kilowatt hours/m² per annum for heat demand, which is a lot lower than the PHPP had suggested. One reason for this might be that Kirsty prefers setting the temperature a little lower in winter at 19 Celsius rather than 20 Celsius.

    The size of the windows matters

    Kirsty stresses the importance of getting your windows the right size, both in terms of heat loss and overheating. It might have been tempting to open the whole south gable end to glass, but she knows she would have cooked in the summer. She still has one large feature window and several other generous sized windows, and says the PHPP process really helps to show where there might be a problem and how to adjust things accordingly. Even though it’s looking at averages and could be regarded as a crude tool it did allow her to model her overheating risk to 0%.

    Skylights can be tricky to shade

    Kirsty included skylights as replacements for vertical windows along some of her walls and explains that you will lose more heat in winter through a window directly facing the sky and it will be harder to shade in summer. She doesn’t feel she has enough of them to cause a problem and one benefit is that they work extremely well for stack ventilation.

    Strathclyde University have been monitoring the performance of the house and office for the last 18 months and both of them are working really well.

    Finding time to work on the project was challenging

    Kirsty is building houses all the time, so from that point of view, building her own was quite straightforward. She knows good consultants who are part of her normal work team that she could bring into the project. The hardest thing was setting aside enough time, because she was having to do all this in her own time. At least she was passionate about it, but remembers finishing some drawings whilst on holiday with friends!

    Be prepared for a lot of digging out on a steeply sloping site

    The groundworks phase started with digging out a lot of material from the site due to the steep slope. There was also a 2.5m high wall along the street edge that had to be taken down and soil removed to make it level with the street to create the parking area and the site for the new office. Kirsty was able to reuse the wall to create the gabions needed on site and collected more stone from other building projects around the village. And her dad even carved her house number onto a piece of stone, which was built into the new wall.

    The house is on an Isoquick raft foundation, with the area around it built up with a concrete block retaining wall, which is insulated on the outside with XPS insulation. There is also a tanking layer to keep the water out, which so far has been working well. Around a third of the building sits below ground. The timber frame is filled with wood fibre insulation with a wood fibre “tea cosy” all the way around the outside including the roof to avoid thermal bridges. Kirsty often uses this technique, particularly when doing a stick build on site. She explains that there used to be few timber kits of Passivhaus quality that were manufactured off-site but now there are some good ones, including Eden Insulation that was used at The Seed.

    Find out more about Eden Insulation in our training session with Stephen Gurney in The Hub.

    The steep slope also meant it was harder to bring materials to site

    Everything had to be carried up the steep slope, most of it by hand. Only the large windows and ridge beam were brought in by mechanical means. Kirsty says it’s also worth checking the largest size of window that can be carried on a normal truck, so you don’t have to cover the cost of non-standard transport.

    It’s about choosing where you spend your money to make the best impact

    Upstairs, there is lots of volume due the cathedral ceiling and this gives it a light and airy feel. There is oak flooring throughout the house with quite simple detailing and lots of plants adding interest. A local craftsman, Imric made some beautiful shelving and built in cupboards, with bespoke worktops coming from another craftsman in Edinburgh. However these items sit alongside an IKEA kitchen, Howdens flooring and bog-standard skirtings, architraves and doors.

    Kirsty tells us that people often comment on a yellow globe light that can be seen from the street, which cost £20, whereas other handmade more expensive light fittings go unnoticed. She also made light fittings herself using coloured cable and used a number of long drop cables to separate spaces. It’s not just about putting up walls up to separate spaces, there are more subtle ways of dividing spaces that create layering and different views.

    If you have a dream explore it with an architect

    Rather than always wondering “what if”, Kirsty’s advice is to find an architect to help you to explore your dream building. It doesn’t mean you are committed to the project at that stage, but it’s good to put all your ideas on the table, sift through them and see where it takes you. You’ll probably end up prioritising them, but later you might find a way to return to these ideas that were less of a priority at the start. Kirsty loves going through this process with clients, even when they don’t know how to articulate what they want, because there are so many opportunities. She finds getting to know her clients and creating that relationship with people a really special part of being an architect. She sees private clients as really invested in the process, with many of them bringing so much of their own creativity to the conversation.

    Passivhaus delivers a healthy and comfortable internal space

    Kirsty sells this level of comfort to her clients and visits them in their houses but still thinks it’s difficult to understand how great it is until you’ve lived in it yourself. She was living in a small, 200 year old flat before building this house, which had all the pros and cons of an old building, but is mostly cold and slightly draughty! Much as she liked being there, she can’t really express how comfortable she is now and how nice it is to have constant fresh air.

    When designing the building, Kirsty layered up so many interactions between the spaces, some subtle and some not, to capture different views. She finds it hard to pick out one thing as a favourite, but it’s probably the views through the building, being able to sit in the living room and look out all the way across the Tay Estuary to the mountains.

    Find out more

    Kirsty Maguire Architect

    How to incorporate reused materials on a self build

    Progressing your house build plans before you have your land

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  • HPH384: De-risking a Passivhaus project – with Sally Godber

    HPH384: De-risking a Passivhaus project – with Sally Godber

    Sally Godber, a Director at WARM consultancy explains why reducing the risks on her own Passivhaus project was so important, what that entailed and how it enabled her to deliver a healthy, comfortable and energy-efficient home on budget.

    Interview with Sally Godber

    Sally is a Chartered Mechanical Engineer and Passivhaus certifier who co-founded WARM consultancy with her father Peter Warm. She grew up with her dad building different houses, always experimenting with designs and construction systems to improve energy efficiency. It was never her intention to work in this field but somehow it had seeped in by osmosis, and after university and her growing awareness of the climate crisis she wanted to work in sustainability. With her engineering background she had gone into building service design, but it wasn’t rounded enough for her as it only dealt with a small part of the building process. Combining her experience from the commercial sector with her dad’s hands on practical experience and knowledge of domestic builds resulted in WARM energy consultancy. Their services include Passivhaus consultancy and certification, focusing mainly on commercial building projects. They also offer training through their sister organisation, Coaction.

    The juxtaposition of her work and her home situation became too much

    The driver for taking on a project came after living in a large, damp, Victorian house, whilst working on Passivhaus projects for other people. Initially Sally and her husband Mikey had started looking for a new home, but they found themselves wanting to change everything other people had done, which felt pointless. Either they needed to find somewhere that required a lot of renovation or to start from scratch.

    Managing risk became an integral part of taking on a project

    For Sally the prospect of taking on a new build or retrofit was exciting, but her husband Mikey was not so sure. So when they sat down at the beginning to discuss their priorities, risk came up. For Mikey, above anything else he did not want to be crippled financially by chasing the self build dream. Luckily a large part of Sally’s professional life is spent de-risking projects and also having had ‘the big house’ experience she was after the polar opposite.

    Scaling down a project scales down costs

    With a tight budget one of the most important decisions you’ll ever make is setting the size of the project. If you make it too big then it will be impossible to get the quality you desire. Sally and Mikey wanted to build to Passivhaus standard, but beyond that they just wanted a modest sized, warm and comfortable family home.

    “We had a young family, I had my business going on, and my husband was not totally sold into this. We really needed something that was going to be low risk. So all of the design work that we did was about being able to manage the budget.”

    Risks can often be identified

    Sally outlines multiple risks and how many of them can be reduced through good design. She explains that some risks start with our expectation about how a project is going to go and then the reality of what actually happens. We might be faced with cost increases or there might be a failure during construction, for example, through something not being protected on site, which results in water damage. In terms of the energy performance, the airtightness, the insulation continuity and the build quality are key. Sally sees projects go wrong when the contractor is not clear about the expectation for the build, or the design contains many complex details, which have been hard to price in advance. Although it’s a quantity surveyor’s job to cost up projects, when the design is complicated it’s much harder to work out accurately the time and effort needed to complete the build to a decent quality. So, the difference between the client’s expectation and reality could be quite significant.

    Reducing the number of ‘unknowns’ reduces the overall risk

    Sally will always look to pay a fair price for building work which has got the least of number of unknowns within it. She explains that it is impossible to take some guesswork out of retrofit projects because you can’t know what you are going to find. Likewise, there are always some unknowns around groundworks, but for a new build, once you are out the ground, the risks come from the things that you’ve added into the design.

    Complexity increases risk

    This means that the amount of risk you have on your project is down to how complex you’ve made the design. These risks can come from the geometry of the building or the construction choices. Sally explains that making good decisions during the design process may not save you money on paper, but reduce the risks of you having to build to a poorer quality and it not being what you wanted.

    “The amount of risk that you have on your project is about how complex you’ve made the design.”

    Know your absolute price when buying at auction

    Sally and Mikey considered a few plots and existing dwellings, before spotting a dilapidated pub at auction. Key opportunities included it being in a great location in Plymouth, which was at the entrance to the historic naval victualling yard and near to the WARM office, and having a sizeable garden with a beautiful old Holm oak tree in it. So they decided to bid for it.

    A top tip that Sally received from a friend is to work out your absolute maximum offer in advance of attending the auction and then not to go above it! While this may seem basic advice, as a novice it’s easy to get swept along in the moment.

    Sally also gets the feeling that most people at auctions are professionals, who are representing investors, so you will be competing in this arena. However, overall she thought it was a great way to buy a building, particularly because it’s so quick. Their last bid was their absolute maximum, so the adrenaline levels were high but they secured the property.

    Living in the pub gave them a better understanding of the work that was needed

    The pub had a flat upstairs, so they decided to live in it for a year to help get an idea of the space and make sure they understood what the retrofit required. They quickly realised that the pub was more dilapidated than they had thought, it wasn’t well connected to the garden and the refurbishment would cost a lot more than they were planning to spend. So they explored another option instead, which was to build a new home in the garden and then refurbish the pub at a later date.

    Achieving planning permission was an emotional roller coaster

    Sally has a lot of empathy for people who have been through the planning process or are going through it, as it was a real headache. It didn’t seem to matter that they wanted to build a good quality, high performance building that would fit into the local environment and last for generations. It felt like a lottery, particularly when they’d had a positive response to their pre-application, only to be turned down on their full application. Luckily their architect Jae Cotterell got involved and was able to present a good case for why it should be granted, and the planning department eventually saw sense and gave it the green light.

    Working with one company for the design and build was part of their original de-risking strategy

    Sally tells us that part of their de-risking strategy was to get Passivhaus Homes involved. Not only did they supply a kit that was tried and tested, and would easily reach the Passivhaus standard, but at the time they were also doing the construction work. So keeping the design and build with one company was a way to get cost certainty.

    With her second child on the way, however, Sally was keen to get moving as soon as possible. Unfortunately the time frame for Passivhaus Homes to carry out construction didn’t work out, so they considered another option.

    Their simple design made it easier to engage with another timber framing company

    The positive side of all the work they had carried out in the design stage to de-risk the build meant they could approach a more standard timber framing company.

    A simple design reduces the risks during construction

    The house has a simple rectangular form with a pitched roof. On one side there’s a single storey element with a flat roof to provide a view for their neighbours. This added some complexity to the detailing and being close to their neighbours also meant they had to lower the eaves on one side of the roof.

    The floor area internally is 120m² and it was a priority for Sally to make this space work hard. Downstairs is an open plan living room and kitchen, which has been designed so that a wall could be added later if they ever want to separate the rooms. There is also a spare bedroom downstairs, along with a utility room and a downstairs bathroom. Upstairs, there are three bedrooms and one bathroom.

    The emphasis was on making the spaces work, with Jae encouraging them not to scrimp everywhere! For example, creating a welcoming and spacious hallway was something they didn’t appreciate at first, it felt like a waste of space, but over time they have realised how valuable this is.

    There were challenges using a standard timber frame

    Sally explains that Passivhaus Homes use a portal timber frame, which doesn’t require a ridge beam and allows you to create spans without any supporting beams. Unfortunately, standard timber frame manufacturers are not used to doing the lift of the ground floor and first floor in one which is what you do with a portal frame. Separating it into a ground floor timber frame and a first floor timber frame meant that they needed steel beams to provide support. Sally hadn’t wanted to use steel as a material in the build and this then created some difficult detailing for the airtightness. This is where the standard timber frame suppliers really struggled and if it hadn’t been so late in the design process Sally would have changed the design to break up the spans, so they could still have used timber. She feels it’s really important for designers to understand the natural limitations of different materials rather than relying on engineers having to solve problems because you’ve created a span that’s too wide.

    Allwood Timber supplied the twin stud frame, which was then filled with Warmcel insulation. They have insulation under the slab and the roof is treated the same way as the walls, with blown-in cellulose. The structure is I beams, with OSB board on the inside.

    Another advantage of a simple design is that you can run your eye over everything to see it’s all in order, such as making sure the airtightness line is continuous.

    Remedial work enabled them to achieve the airtightness target

    They did some of the taping themselves, along with the timber framer and after a poor first air test (1.2 air changes per hour at 50 Pascals) they realised they hadn’t pressed down the tapes enough. As soon as they did this and activated the glues, they saved another 0.2 on their air test. There was also air leakage around the steel beam. If she’d done the project today Sally would have used an airtightness paint to sort this out, but back then she had to spend a late night putting a lot of tape on it. Their final air test achieved 0.56 which meets the Passivhaus standard performance criteria.

    Their windows and doors are from Rationel, because Sally had used them before and knew they were relatively cheap in comparison to others. They also designed all the windows so that they could be openable with a single span, with a lot of them being top hung so they could leave them open at nighttime. They’re a simple design with easy detailing, which all helped during construction. Sally feels it was still hard to achieve good airtightness when they didn’t have a lot of time themselves to check things and weren’t working with people with experience of this type of build.

    They achieved a better airtightness with the pub retrofit a few years later, working with a local contractor called Greenacre Design and Build who had an amazingly skilled team. They were great problem solvers and fantastic at detailing, so they did exceptionally well even though it was their first time doing a Passivhaus retrofit project. But sometimes you don’t have those teams, and so being able to keep the details simple is really helpful.

    Sally took over managing the build as soon as it was watertight

    Sally made the decision to take over the project once the building was watertight. This meant they could project manage, be in control of the individual contractors and communicate directly with them. For example they got a contractor in to do the plastering and did all the services themselves, apart from the final electrical bits. They brought in a friend, a carpenter, to do the internal finishes and he refused to use soft wood! This really put quality into the build and is now much appreciated by Sally and her husband. It did take longer to complete the build as they were quite restricted with the time they could make noise in the evenings and at weekends, but it was good to feel more in control.

    “We found that once it’s watertight, it feels like you can just breathe a bit, and it’s a bit easier to manage.”

    It’s worth taking the time to get things right

    It took two years from the point where they bought the pub to them being able to start construction and one year to do the build. The first year was deciding what they wanted, going from the pub renovation to a new build, then another year designing and getting planning permission. At the time all the faffing felt frustrating, but seven years on she can see that it was worthwhile and meant they ended up with a better home that will last them much longer as a family.

    Sally had also learnt from her parents’ projects that it’s best not to move in until the house is finished as the work just doesn’t get done after that. One of the things they hadn’t done was tile the kitchen, which was only done six years later!

    The house was delivered on budget, but the time put in hasn’t been calculated

    It was a real success for them to deliver the project on budget, but with a self-build the amount of time put in is huge and something Sally doesn’t want to calculate.

    There were some complications during the build, not necessarily associated with the design and things that they would definitely do better next time. They were very careful and conservative to achieve their budget and there are some things they might want to be different. Luckily noticing the faults wears off with time and over the whole project there is just one window that Sally wishes was larger.  She was worried during the build that they were being too careful and maybe the building would feel mean, but it doesn’t.

    “If you are on a tight budget, it makes a huge amount of difference feeling in control and that was ultimately why we took on the self-build.”

    Managing the contractors themselves meant there was no middleman, they could negotiate individual prices and have conversations about the materials they were using.

    Sally describes herself as a Passivhaus geek, but even so there was so much she didn’t know. This has given her a huge appreciation of all the different skills needed in a team to complete a build project.

    She tells us how she really enjoyed the whole experience, both stretching her mind and also physically doing stuff. She doesn’t think there’s enough of that crossover, with designers getting practical hands-on experience.  With the pub finished three years ago she’s definitely ready for another project but has nothing particular in mind.

    Sally got to appreciate Passivhaus certification from a client’s perspective

    They had designed the house to Passivhaus standard but hadn’t discussed certification until they were just about to start the build. Sally tells us that at the time she was absolutely exhausted and didn’t think she had the energy for it; it would be just too much hassle. Her dad, who doesn’t often tell her what to do was very clear that not doing it wasn’t an option, particularly considering her job!

    They employed Will South of Etude to do the certification so that they had someone independent looking at the project. In the end, the certification process proved incredibly valuable for Sally as she knew there was a second pair of eyes checking on the project details. She was doing her best to check things but was incredibly busy and Will picked up on a few things that were wrong. Will had identified that they’d got their shading wrong, which they were able to correct, but it was too late to change the insulation, which was not the right specification. They had enough margin in the calculations for this not to matter, but by identifying it early they could have made adjustments elsewhere if they’d needed to.

    It also gave Sally a real appreciation of just how hard it is as a client getting everything together for certification and the need to find the right level of checking. She is still a massive advocate for certification and as there’s very little quality control it’s good to have someone whose sole job is to check that you’ve built what you said you were going to build.

    Sally’s husband is now an advocate of Passivhaus!

    Sally says her husband wasn’t totally onboard with MVHR, triple glazing or even achieving the Passivhaus standard, but she was clear that these things would be worth it. They’d moved from a large Victorian house that was uncomfortable and difficult to manage into a tiny pub flat where she was cleaning mould off the walls. The flat was just 60m² and inevitably there were arguments and conflict. So, the experience of moving into somewhere that was a lot bigger was obviously like a revolution for the family. Sally tells us that it was so warm in the house that the kids wouldn’t believe they needed to put on coats to go outside. She had been spouting the theory to everyone, but it was still amazing to experience the comfort and warmth for herself. Her husband was quickly converted to this way of living. They also realised how they’d stopped inviting people round to the pub flat because it was so damp and at the time Sally hadn’t realised just how much inherent stress the mould and the dampness were giving her. She admits to being a total snowflake now, finding it very difficult to stay in other people’s houses.

    Try to enjoy the whole house-building journey

    In hindsight Sally reflects on the self build journey as a really lovely process, but this is not always how it feels at the time. She gives an analogy of when you have young kids you can feel like your hair is on fire, you’ve got sick down your front, and you’ve just stepped in something you’d rather not have. But when you look back, you think that was an absolutely incredible experience. She says to find ways to bring your family together through the process and the same with your wider building team. The relationship side of a building project is really important. So, as much as possible try to enjoy the sick down the front feeling!

    Find out more

    WARM

    Coaction

    Passivhaus Homes

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  • HPH382: What is a Principal Designer? – with Ben Nother

    HPH382: What is a Principal Designer? – with Ben Nother

    Ben Nother, a Director at Hawkland Group, explains the two different roles of Principal Designer in meeting building regulations and addressing CDM health and safety. He also reflects on how this has been integrated into their processes.

    Interview with Ben Nother

    Ben Nother comes from a family of builders and bricklayers, and this is exactly where he started, on site as a labourer working on different construction projects during his teenage years. He was then encouraged to go into the professional side of the industry and chose architecture, studying at both the University of the West of England and then the Centre for Alternative Technology. This allowed him to delve into sustainability issues and the challenges of climate change. After 5 years working for different practices, he became freelance to find a better work life balance. Gradually he developed a good working relationship with Hawkland Group, eventually joining their team as a director.

    In this conversation Ben is giving us his take on the Principal Designer role. For a more detailed explanation of the Principal Designer duties and responsibilities check out the guidance on Gov.uk.

    The role of Principal Designer has evolved

    Until recently a Principal Designer was the person who focused on meeting the Construction Design & Management regulations (CDM), from the Health and Safety Executive. Essentially, they would consider everything needed to ensure health and safety on a construction site. A Principal Designer would start with the design risks within a building project to see if they could be eliminated and if not, identify how the risks could be managed. For example, you may not want to design out a rooflight, so identify that there is going to be work at height, which is then a risk to be managed. A list of risks is given to a Principal Contractor who can put in place the relevant health and safety measures, such as scaffolding and the need for harnessing.

    CDM Principal Designer and Building Regulations Principal Designer

    Following the Grenfell tragedy, the Building Safety Act was revised in 2022, with all the regulations gradually coming into force by 2024. So there are two roles that fall under different legislation frameworks which both use the title Principal Designer.

    So, to reiterate, the two areas to be addressed are:

    • CDM health and safety.
    • Compliance with building regulations.

    The Principal Designer now takes on more responsibility and liability

    Before these changes, an architect would pull together drawings and information on thermal performance, fire safety, structural engineer’s calculations, everything needed to ensure it would meet the building regulations. These would then go to the local authority or an approved building inspector to be assessed and signed off. The new regulations have changed the responsibility chain, so the Principal Designer is now more liable for those building regulations and is now co-signing them off with approved building inspectors.

    As they are the designer of the building, they know what’s going into it, the performance that it should achieve, so have the responsibility that it will meet the building regulations. The Principal Designer will now also be doing site inspections to ensure that the builder has complied with the suggested interventions and will supply evidence for the building inspector. Architectural practices, structural engineers and others can provide this Principal Designer role.

    Different people may take on the role of Principal Designer during the project

    Today Hawkland Group has two brands: Hawkland Architects and Hawkland Construction. Historically, however, Hawkland was a contracting company. So clients often approach them post planning for input on the construction of a building. The client may have a full package of information that has been taken through to technical design. In which case the architect or the structural engineer working on the project, would be the Principal Designer, with Hawkland Construction, then taking on the Principal Contractor role. In other cases, Hawkland Architects may take on the design work from stage four, post planning, and so would take on the Principal Designer role as well. Under the new Building Safety Act, they would be looking for a comprehensive handover from the previous architectural practice or designer who has put together stage three, with all the identified risks and mitigation measures.

    Ben likes their approach at Hawkland Group, where they can take responsibility for a project from concept to completion, because they can put together a robust set of both CDM and building regulations information. Otherwise he’s working from someone else’s information, checking it, trying to fill in gaps for something already part designed. This could well mean a doubling up on time going through someone else’s designs and information.

    The Principal Designer role continues in the build phase

    The Principal Designer role continues through the build and as the person most familiar with all aspects of the build they will make sure that each company brought in is competent, has the relevant insurances and qualifications and that the design being put forward is compliant and safe.

     “…having a Principal Designer all the way through as one person is key, because they know all of the different moving parts on that project.”

    The client must understand who the Principal Designer is

    Under the CDM regulations, the client is ultimately responsible for health and safety on site, but they can shift those responsibilities to their Principal Contractor. The client protects themselves by bringing in people with the relevant qualifications and right insurances to deliver their project. At Hawkland Group, they may take the project to a weather-tight shell, with the client then overseeing other contractors and perhaps also doing some of the work themselves. In this instance, the client takes on the responsibilities under CDM and now the new Building Safety Act, with Hawkland Group providing the drawings and information up to the technical design stage. They can also sit in the background to provide ongoing support for the client as the project progresses. If a client is going to assume the Principal Designer role it’s really important that they have the skillset and knowledge to do this. There’s more advice at Gov.uk.

    For someone doing their own designs and planning to undertake the build themselves they are taking on both the responsibility for health and safety on site and meeting building regulations. They need to know the risks around the building site, be able to induct specialist contractors to the site and be aware of everyone working on site. Ben recommends getting advice on the processes needed on construction projects as well as having an architect sense-check the designs.  

    There’s more from Hawkland Group in The Hub. David and Chris give us an overview of how to convert a loft.

    There are multiple considerations for the materials and products being used

    There will be health and safety aspects to consider under CDM alongside performance issues to be met for the building regulations. For example, some modern methods of construction may require that wall panels be lifted with specialist gear under CDM. If a crane is required, that needs to be able to get safely onto the site. The building regulations will consider the performance of those materials from a structural or fire safety perspective. The company producing the materials should be able to provide evidence of how they meet the different regulations. At Hawkland Group, they sometimes use straw direct from farmers, which won’t have those classifications for each bale, but fire tests have been done to show how that material reacts with fire. There is a bank of information for many natural materials now being used in construction.

    Manufacturers generally have all the information you need for products

    Manufacturers will also have standard build-ups that they know meet the regulations providing you use the materials in the right way with suitable ancillary products. The information is available but needs to be collated for building regulations sign-off. There are also instances of chemicals that need specialist handling and safe storage on site. An architectural practice will go through the specification process early on, so they know what needs to be done on site for health and safety, and what needs to be evidenced with building regulations.  

    The regulations should be front of mind from the outset

    Ben is now considering health and safety issues and building regulations as early as possible. If a client comes to him for example wanting a balcony, he will immediately look at the regulations around this. How high does the balustrading need to be, how high is the balcony off the ground, can it be a fire escape route? It’s important to look at this straight away as it may impact the designs across the rest of the building and it will need to meet building regulations. In the past something may have been designed for planning with no real consideration of how it was going to be built. Ben now has those conversations straight away and will know what products he wants to use from the concept design stage.

    The welfare of your build team is important

    Hawkland Group takes pride in their sites having good working conditions, being safe and inclusive. For example, the staff toilet could be a portable potty 20 metres away from the building where you have to brave the elements or it could be part of a comfortable staff welfare unit. On smaller jobs this might not be possible because space is tight and in Bristol, where they often work, sometimes their clients offer a room for them to use. Their site team also usually work four slightly longer days each week to give them a three day weekend and a bit of flexibility.

    A client can intervene if they are not happy with health and safety measures on site

    As a client you have a responsibility to raise concerns if you see that things could go wrong on site. It’s best to raise any issues with the contractor immediately and whilst they are responsible for Health and Safety on site you are well within your rights to challenge their approach and tell them they are not meeting CDM regulations. Hopefully they will be keen to adjust their way of working because there are significant penalties for not working safely. You could also raise it with your Principal Designer, for them to follow up. In a worst case scenario you could even terminate the contract, but this will leave you with some major challenges.  

    Hawkland Construction and many other contracting companies will have a site manager who is overseeing health and safety during the construction phase. Everyone is responsible for health and safety on site, but the project manager will help with regular inspections to see that everything is working well. It is also good practice to vet different companies beforehand, maybe visit a site they’re working on so you can see how they operate, not just a finished project. Checking they have the correct insurance cover is also important.

    There are advantages to having one principal designer for both CDM and building regulations

    For Ben it makes sense for one person to be responsible for both CDM and the building regulations. Whilst they cover slightly different aspects of the build they do go hand-in-hand. The Building Safety Act as part of its legislation, says the Principal Designer must be a designer, so ultimately it will an architect, or possibly a structural engineer. Ben explains that all the other designers on a project have to agree that the person appointed as the Principal Designer is competent to do this role. Under CDM, you can still use other companies to provide an independent Principal Designer role, so maybe a specialist health and safety company to support this aspect of the build. For a self-builder this could provide valuable support and technical information that you may not be familiar with.

    “The processes for building regulations and CDM are complicated. It’s really hard just to do it by yourself… it’s key in bringing in competent companies and competent individuals to be able to help you deliver your project.”

    Using one company for the whole project can simplify things for the client

    Whilst Hawkland Group can come in at any stage of the design or build process they also offer a complete service, where they deliver a whole project from start to finish. By overseeing the whole design process and technical phase of the build or retrofit there is then an ease of transition into the construction phase.

    Ben feels that this allows for continuity and good communication with the client and with everyone working on the project. The architectural team and construction team work closely together so that when it comes to pricing up for construction everyone is aware of the design and has been considering the type of build and looking at budget feasibility assessments throughout. Being very open with a client allows a better flow of information and can help achieve quicker decisions when things need to change during a build. It also allows for earlier investigative work to understand the type of issues that may come up, so you can be proactive rather than reactive.

    Find out more

    Hawkland Group

    Hawkland Architects

    Hawkland Construction

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  • HPH381: What is Passivhaus Premium? – with Phil Neve

    HPH381: What is Passivhaus Premium? – with Phil Neve

    Phil Neve explains what Passivhaus Premium is and why he chose to target the standard for his own self build in Somerset. He also talks through his biggest project challenge, which was obtaining planning permission to build in open countryside.

    Interview with Phil Neve

    Phil Neve started his working life as a scientist and oceanographer. He always had a deep interest in alternative energy, and so eventually retrained as an energy consultant and Passivhaus Designer. He then spent 15 years working exclusively on low energy and Passivhaus buildings. Now retired, he is five years into his own Passivhaus Premium project, which has finally got planning permission under Paragraph 84 of the National Planning Policy Framework.

    In the last podcast we talked about Passivhaus Plus with architect Heather Johnson. In this episode we’re looking at the Passivhaus Premium certification and how it differs from the other Passivhaus classifications. We’ll also explore some of the challenges that meant this project was on the drawing board for five years!

    Renewable energy generation on a Passivhaus Premium project will produce a surplus

    While Passivhaus Classic focuses just on the energy consumption of the building, Passivhaus Plus and Passivhaus Premium bring renewable energy generation into the certification process.

    In addition to all the criteria for a Passivhaus Classic, a Passivhaus Plus project must generate as much energy as it uses over the course of a year.

    Passivhaus Premium takes this even further, so that a surplus of energy is produced. Phil explains that this is calculated according to the floor area and the potential of the piece of land.

    Typically a Passivhaus Premium project might produce two to four times the energy it uses. Whereas a Passivhaus Plus project will import energy from the grid in the winter, a Passivhaus Premium will rarely import energy. So the goal of this is to export a significant amount of energy to the grid. This also starts to affect the operational carbon calculations for the building, because you are producing zero carbon or very low carbon energy on top of what you need.

    A Passivhaus Premium project will require permission to export to the grid

    If you’re looking to export above five kilowatts to the grid, which will be a certainty on a Passivhaus Premium project, you will need approval from the District Network Operator. Another must is that you have a three-phase electricity supply.

    Solar PV is often the most practical choice of renewable

    Although any renewable can be used for a Passivhaus Premium project, as with Passivhaus Plus, generation tends to be with solar PV because it can be integrated seamlessly with the building and is generally much more accepted technology than wind turbines, etc. However, if the site has a natural resource to harness, for example being next to a watercourse, then obviously other methods of generation may be preferable.

    Phil’s horticulture project

    Getting consent to build in open countryside can be expensive and time-consuming

    Phil’s self build journey began with a piece of land he owned for a horticultural project. He had absolutely no intention of building a house, but over time things changed. Unfortunately he knew that there was probably only one way to get planning permission to build on a site like this and that was to use the Paragraph 84 exception clause (previously referred to as Paragraph 80, Paragraph 55, etc.) of the National Planning Policy Framework. This allows exceptional one-off houses to be built, where quality is essential and the proposed dwelling significantly enhances the rural setting. However, it’s a lot of work, comes with numerous costs and is all at the self-builder’s risk until consent is granted.

    A satellite view of Phil’s site

    A Paragraph 84 permission often requires consultants

    Whilst Phil felt he had an advantage with his background in construction and environmentally sound building, he was fully aware that he would still require a lot of help. He tells us that he has ended up employing around 10 consultants, sometimes two per topic, covering; architecture, planning, landscape design, ecology, highways and highway safety, and lighting! On top of that there was a design review process using an independent design panel, which was long-winded, complex and expensive. Phil knew all this was coming but it still came in at twice the budget he’d expected.

    A Paragraph 84 consent requires deep pockets

    One of Phil’s initial aims was to prove that exceptional house design under Paragraph 84 needn’t just be for mansions. Exceptional projects can be small scale and not break the bank. He admits he may have been a little naive about this but still believes he can bring the project in at a reasonable cost as a “sweat equity” self-builder.

    Phil has an unshakable belief that we can create great buildings that are efficient, comfortable and healthy. We have the skills, knowledge and materials to do it, but we’re not doing it at volume. He feels that what most people are offered when buying a new house is rubbish and it needn’t be. So, he wanted to show that it could be done better and still be affordable.

    ‘Exceptional’ in this case is pushing the boundaries of what can be achieved

    Phil wanted great performance from the building and to maximise energy generation, and so he targeted Passivhaus Premium. It also had to look good, be beautiful to at least some people, and be very low carbon, pushing the carbon budget down as far as possible. Beyond the house he wanted to improve the biodiversity and ecology of the whole site.

    The size and design evolved over time

    When Phil started the design process he was living on his own and looking at a two-bedroom house around about 120-140 square metres. As he now has a partner, the design has evolved into a more standard 3-4 bedroom family house of around 230 square metres.

    In terms of Passivhaus design, he spent a lot time considering the form (or shape) of the building. The form factor can have a big impact on the ease of construction and the cost. A good form factor is two, with a poor form factor above four. Phil’s house comes in at 3. Early modelling of the building showed that it could achieve the Passivhaus standard, and that Passivhaus Premium was within reach with a PV array on the roof of the building. The overheating risk of the final design is zero.

    “These ideas evolved into the concept of a wedge-shaped house with a single pitch roof facing south.  A very simple design which works very well.”

    A Passivhaus doesn’t have to be a boring box

    Phil explains that to achieve an interesting shape for a Passivhaus there is some compromise on efficiency. However his design will create a fantastic south-facing roof for around 22 solar PV collectors, which will allow them to achieve the renewable generation targets. Internally there will be some sloping ceilings and slightly odd shapes, although Phil believes this adds to the aesthetic.

    Minimising the overheating risk has been a priority

    During the design process there is a balance to be achieved with solar gains. While these are beneficial to keep the house warm in the winter they need to be controlled to prevent overheating in the summer. For Phil’s project there are large windows on the ground floor of the south elevation, but these will be shaded from the summer sun with a 1-metre overhang. For the east facing bedroom windows, in addition to overhangs there will be some vertical shading. Phil also intends to grow plants up that side of the building to help shade those rooms. The building then becomes a place to grow things like hops and vines, producing food as well as providing shade.

    Finding a collaborative architect was important to Phil

    Phil chose friend and architect Mark Ellerby to work with him on the design as he wanted someone independent with good design ideas, who would also be receptive to his input. He says they’ve worked through challenges and ultimately produced a design that works and has satisfied the design review panel.

    The Design Review Panel want to understand how you’ve arrived at the designs

    When a panel of experts are reviewing your design it can feel subjective, because they decide if it is outstanding architecture and suitable for Paragraph 84 permission. So Phil explains that you have to show how you got to the final design – show your workings – and justify the decisions you’ve made.

    Improving the ecology of the site has been a huge focus

    How to improve the land for biodiversity has been a top consideration for Phil, so he asked his ecologist to show him everything he could do to increase biodiversity. He was also aware that they needed to convince people that they would actually put this into practice.

    There are rules and regulations to meet as well as the requirement for biodiversity net gain calculations, which seem to conflict with what is needed for the bat populations. He has had to show that the bats won’t be disturbed by light coming from the house through light spill surveys including a 3D model of the house. This has been agreed by the county ecologist and is now with English Nature for their approval.

    “To anybody embarking on a Paragraph 84 house, you have to look at everything in detail early, predict the problems and be ready to go out and spend the money to get the answers.”

    For a Passivhaus Premium you must be able to export to the grid

    Phil had originally thought about building off-grid, but to be certifiable as Passivhaus Premium you need to be able to export energy to the grid, otherwise you are potentially wasting the excess energy you produce. He now thinks you should only be off-grid for energy and water if you absolutely have to be. All the energy you export is contributing to a low carbon energy supply, and you can access energy yourself if needed.

    Even before construction begins, Phil got a three-phase supply installed at a cost of £2000, and he will then have to run another 100 metres of cabling to the house.

    PHPP calculates the primary energy target for the renewables

    In addition to all the modelling that takes place in the Passive House Planning Package (PHPP) for a Passivhaus Classic project, for Passivhaus Premium there is an extra PHPP calculation for primary energy, which helps work out the renewable energy target. It calculates it in two different ways, so there’s some flexibility as to how much you need for different buildings. Phil’s target is 22 kilowatts. Just to illustrate how significant this is, the average maximum installation in the UK (without planning permission) would be about four kilowatts!

    So there will be 100 square metres of solar PV, which will also be the roof covering. Phil will be using a small ground source heat pump in addition to the PV to provide all the heat and hot water they need. He may add batteries eventually, which with the right switching gear would provide a buffer against power loss from the grid.

    A tried-and-tested build system will make life easy

    Phil is very familiar with the PH15 system, having been part of the Passivhaus Homes team for over a decade.

    Rather than reinventing the wheel with every new design, PH15 makes it easy to achieve Passivhaus performance. It is essentially as simple as you can make a timber structure. Structural I-beams provide the physical strength and form to the building, with a layer on the outside, which is insulation and a layer on the inside which is closing the cavity. This is the racking board, the airtightness and vapour permeability layer. This creates a box, which can then be filled with processed wood insulation. 85% of the structure is insulation, it’s structurally sound, made of natural materials and is airtight.

    During the first couple of weeks of a build, all you’re doing is screwing things together. Phil describes it to clients as an Ikea flat pack house; it just comes on a truck instead of in a box! For Phil the other good thing about the PH15 system is that the internal floors are essentially hung on the inside from ledger beams. The roof is the same structure as the walls, essentially a portal frame structure, with the airtightness layer continuous on the inside of the building.

    Reducing the embodied carbon of the building was part of the design process

    Phil explains that for a typical dwelling there may be 40-50 tonnes of carbon within the concrete used in the groundworks and foundations, with another seven tonnes in the superstructure of a masonry house. Phil was keen to eliminate the use of concrete on his project.

    One option was to use ground anchors, which are like metal screws that hold the building to the ground. The building then sits on holding plates, raised above ground with a ventilated cavity. This creates a suspended timber floor instead of a concrete slab. The approach is proving expensive and complex in terms of buildability.

    A lot of people are now using a modification of a standard strip foundation, where you dig a trench, fill it with some concrete then build cavity blockwork, to allow you to pour a slab over insulation. Phil is looking at a compromise between the two, either by using low carbon cement or other materials instead of cement. Chem-free blocks and low carbon pozzolanic materials would reduce the carbon content of the concrete.

    Another option combines limecrete with foam glass insulation instead of plastics. One challenge is that with these products the costs go up and the performance comes down a bit.

    Building on a slope can mean a lot of excavation

    Phil is building on a slight slope and made the decision early on to excavate soil to create a flat site for the house. This was to drop the house into the landscape for shelter as well as the visual aesthetics. Phil says he might make a different decision if he was looking at it today as it means moving a lot of earth around, although the soil will be used on site as part of the landscaping work and to help retain water on site.

    The land sits between a wooded ridge above to the north and lower lying agricultural lands below to the south. The soil is fairly free draining and he’s aiming to reconfigure the landscape with a series of swales and two ponds to gather water before it penetrates down the site.

    Prices have shot up across the board since Covid

    Phil started the project with a working budget for the building of between £1800 – £2,000 per square metre, but prices have gone up massively since COVID. He’s now looking at over £2,500 per square metre and needs to keep it below the £3,000 mark. He is also planning to do some of the work himself to reduce the costs. Phil will be project managing the build with a small team, commissioning items from local people where possible, and avoiding bigger contractors who sub-contract things out and are therefore more expensive. He admits it’s still an unknown, until he’s got detailed costings and is actually building. He’s keeping the landscaping as a separate budget and one or two of the higher cost items, such as the 100 metre electric mains supply, that other people might not encounter. He aims to have transparent costings that can help inform others.

    A slightly longer build programme aims to take the pressure off

    Phil is setting the build programme to around 18 months, rather than a year, so that there is not too much pressure on everyone. He’s in good health, has always been active, and thinks if you have the right project that’s moving forward the time will fly by. He’s also aware that building projects often go through a hiatus somewhere in the middle, when you wonder why the hell you started and whether you’ll ever get to the end. He’s seen that in other projects, so is prepared for it and knows you just have to get on with it.

    Planning has been the biggest challenge

    Phil has a lot of sympathy for planning departments and can see that they are massively under-resourced but the result is that the system doesn’t work, especially for individuals. The big developers can throw money at it, take everything to appeal and essentially sidestep the planning process on the basis of housing supply need.

    “I’ve always said to my clients, if you’ve got planning and land, you’ve got 60% of the job done.”

    Everything Phil has done so far to get planning approval has been at his own risk. He gives an example, of having to pay an archaeologist to produce a strategy for the build and to be on site whilst holes were being dug. That money would be wasted if he didn’t get planning permission. With approval comes 22 planning conditions, four of which need to be discharged before construction can even begin. If for any reason he couldn’t go ahead with the build after approval, at least he would have a site with planning permission, which would be worth considerably more than before.

    It is all about risk prior to planning approval, so he’s had to be very patient and have deepish pockets to pay for it all!  

    Find out more

    Passivhaus Homes

    Transcript

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    Exemplar Sustainable Buildings Awards

    The winners of the Exemplar Sustainable Buildings Awards have been announced.

    This was a one-off event to celebrate the 20th anniversary of the Sustainable Development Foundation. It brought together two alliance partners, the Alliance for Sustainable Building Products and the Passivhaus Trust so all of the entrants had to prove performance and demonstrate careful choice of materials and products.

    There were some wonderful projects, and it’s definitely worth taking the time to dig into the details and watch the videos.

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  • HPH380: What is Passivhaus Plus? – with Heather Johnson

    HPH380: What is Passivhaus Plus? – with Heather Johnson

    Heather Johnson from AD Practice explains what Passivhaus Plus is, how it differs from Passivhaus Classic accreditation and what benefits achieving the standard will afford. She also reveals why most of her clients target ‘Plus’ and outlines the steps to achieve this on a project.

    Interview with Heather Johnson

    Heather Johnson has worked in architecture since the age of 16, starting with a summer job as a CAD assistant. She studied architecture for four years at the University of Bath, with placements and work in Suffolk, where she learnt about barn conversions and rural issues. She then did her Part 2 at the Centre for Alternative Technology as her focus shifted to sustainability. A three-month temporary role at AD Practice back in Wheathampstead, where she grew up, turned into seven years and is where she still works today. Heather is now a Passivhaus Designer and has worked on numerous Passivhaus Plus and EnerPHit Plus projects over the years.

    The performance criteria for Passivhaus ‘Classic’ must be met for ‘Plus’ and ‘Premium’ as well

    Most people have heard of the Passivhaus standard, also known as ‘Classic’ but perhaps less well known are the other certifications ‘Plus’ and ‘Premium’. Before looking at the differences between them, these additional classes must meet the same stringent performance criteria laid out in ‘Classic’. For example the airtightness targets, energy demand, overheating risk and so on.

    In this episode we’re going to focus on Passivhaus Plus and find out about Heather’s own project, a barn conversion, which is aiming for the EnerPHit Plus standard.

    Passivhaus Plus sets a target for on-site renewable generation

    Passivhaus Plus brings renewable energy generation into the certification process, setting a target per metre square of treated floor area (renewable energy generation ≥ 60 kWh/m².a).

    It is a step towards self sufficiency and energy security, and a ‘Plus’ project must cover the home energy usage needs over the course of a year. This does not mean it is off-grid, but that the generation exceeds what gets consumed over a year. So there is likely to more generation at certain times of year according to which renewable is being used.

    Solar PV is the most commonly used on Passivhaus Plus projects

    In the UK, more often than not, solar PV will be chosen as the renewable energy source. The main reason is that most houses are in our towns and cities, where space is a premium and roof space is generally available. The technology has also advanced a great deal over the years. It’s cheaper, more effective and can be integrated seemlessly.

    However, any renewable could be used on a Passivhaus Plus project. For example, if you are beside a watercourse then a water turbine might be appropriate.

    Passivhaus Plus encourages a compact building form

    When it comes to solar PV some key considerations are the roof pitch, orientation and surface area of the roof. If renewable energy generation was the starting point for the design of the house, it might lead us to build a bungalow with lots of roof space. However the surface area to volume ratio would not be good, and therefore we may not reach the other Passivhaus targets.

    “The take home point is you still want to make the building as efficient as possible and then add on the generation.”

    The Primary Energy Renewable factors relect the whole picture

    There’s another characteristic the building must meet.

    Primary Energy Renewable (PER) demand* ≤ 45 kWh/m².a

    According to Passipedia: Renewable primary energy (PER) is the unit of energy generated from renewable resources. PER-factors reflect the primary renewable resources needed to cover the final energy demand of a building, including distribution and storage losses. In the case of a PER-factor of 1.5, a surplus of 50% renewable primary energy is needed to be able to meet the final energy demand at the building. The higher the PER-factor, the higher the required resources and therefore the more important the implementation of efficiency measures in order to avoid compensation from non-renewable sources.

    Permission is required to export electricity to the grid

    Although smaller scale renewable schemes (typically under 3.68kW per phase) do not require permission to export to the grid, a Passivhaus Plus project will need approval from the District Network Operator. Depending on the infrastructure of the local area there may be limitations.

    However, Heather says that she has never had a project turned down, but it is always a possibility.

    Additional constraints make achieving EnerPHit Plus more challenging

    Retrofits can also achieve the ‘Plus’ certification. The main difference between a new build and a retrofit is the additional opportunities that building from scratch affords.

    With an existing building the orientation is set and without significant work so is the roof space, orientation and pitch.

    Amongst Heather’s design process she is keen not to break up the long parts of the roof, which are best for energy generation, with rooflights or other roof forms.

    There may be other challenges, as well, such as planning restrictions if a property is in a conservation area. This was the case with Harpenden EnerPHit Plus but a whole roof pitch of solar PV was eventually accepted.

    Heather makes a comparison between the Harpenden EnerPHit Plus which spent £95 on electricity for a year, and her office which typically spends around £200 a month, so it is a huge saving!

    On another retrofit project it made sense to rotate the roof by 90 degrees. This not only increased solar generation but created a mezzanine with a view of the surrounding countryside, which the client didn’t have before.

    Solar PV has come a long way and can now look fantastic

    There can be a double win from maximising generation because a whole roof pitch of solar PV can become the roof finish as well, saving money on tiles, etc.

    Heather often uses the GB-Sol, Infinity system, which is completely seamless.

    On a Passivhaus Plus project in Wheathampstead there is a more conventional in-roof solar array, which does not cover the whole roof. The solar panels are inset so they’re flush with the concrete tiles but it’s not a seamless finish. Interestingly, the clients wished they had put more solar PV on the roof.

    Heather say the cost of solar PV has come down dramatically from when they were first being installed. Unfortunately, the feed-in tariffs for exporting have also gone down, but there is still a much shorter payback period.

    There are also schemes around, such as Solar Together in Hertfordshire, that give discounts for solar installations. It’s becoming a much more attractive offering, especially with more people opting for electric cars.

    Solar PV does not just have to be on south-facing roofs

    South facing roofs tend to work best for solar PV but that doesn’t mean it ends there. When Heather speaks to the suppliers and specialists, they’re quite keen on southeast and southwest as well. This gives a longer period of time generating power, so can be better for the homeowner and takes pressure off the grid at peak export times. North facing won’t give as much generation, but a mixture of orientations will give more consistent energy generation throughout the day.

    Use as much of the energy generated on site, before exporting

    There’s normally a hierarchy of uses for the energy that is generated on site.

    For example, it may be running a heat pump, topping up the hot water, charging a battery or an electric car. So exporting to the grid would be the last option.

    Different suppliers also pay different rates for exported electricity and these rates will probably vary during the day. So if you have a home battery you can maximise your return by importing and exporting at specific times. For example, if you need to draw from the grid to charge your battery it makes sense to do it overnight when the tariffs are low.

    Heather even wants to make her ‘long, thin barn’ an EnerPHit Plus

    Heather and her husband fell in love with a barn in rural Hertfordshire, which was ripe for modernising. It’s a long thin brick building that is not really conducive to a Passivhaus project, but this has not deterred them!

    The first air test achieved 0.7 air changes per hour at 50 Pascals so it’s well under what’s needed for the EnerPHit standard.

    As they are targeting EnerPHit Plus, the large roof area makes it easy to achieve the required generation and they are looking to install around 50 solar PV panels.

    Heather’s barn is being converted in two phases

    Heather is converting the building in two phases. As it is long and thin (around 25 metres) the barn will have two MVHR units (to limit the length of duct runs). Phase one is the old traditional barn, the taller area, with a side utility room and shower room that’s run off one system. They plan to put up a temporary wall up at the end, so they can live in that part of the house, studio style, whilst they carry on fitting out the rest of the house.

    A new timber structure is being built within the old barn

    Heather is taking a similar approach to this barn conversion as they did at Stirley Farm. They are building a timber box within the old brick structure.

    So there’s an insulated slab (the Isoquick system) and I-stud walls which are filled with cellulose insulation. The new extension will be finished with timber cladding, whilst the existing barn will be the existing brick, retaining the historic fabric.

    The design does not add any loads to the original building as that would have required underpinning. The existing timber trusses have been retained and now function as tie beams within the new timber frame structure. Heather explains that because the building is essentially a long tube, it needs the beams to stop it just squishing and falling flat.

    Dealing with ventilation and moisture across the old and new structures

    Heather outlines that where they’ve built against the brick wall, they have a nominal 50 to 100mm cavity, which is much wider in places because the brick walls are not straight. With the new timber clad structure there is a rain screen system, which is battened and counter battened out before the cladding is put on. The timber frame is also wrapped in a membrane before the cladding goes on, so any moisture would hit the membrane and trickle out the bottom, as with many similar systems.

    The bigger risk with phasing the work is that they don’t ventilate the uninhabited internal spaces correctly. As it is airtight and insulated, they need to make sure air is circulating by using fans and opening windows. Otherwise condensation could occur which would eventually lead to mould.

    Find out more

    AD Practice

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  • HPH379: What is inclusive design? – with Stephanie Kyle

    HPH379: What is inclusive design? – with Stephanie Kyle

    Stephanie Kyle from Floyd Slaski Architects explains how we can design for disability, gender, religion, and anything that’s considered a protected characteristic under the Equality Act. She also highlights the biggest challenge of inclusive design which is people’s differing needs, and suggests how we best go about designing spaces.

    Interview with Stephanie Kyle

    Stephanie Kyle is a Senior Architect and Inclusive Design Consultant at Floyd Slaski Architects, who specialises in design for neurodiversity.

    Stephanie was diagnosed with Auditory Processing Disorder (APD) when she was a child, but it wasn’t until her 20s that she found out she was autistic. APD is a neurodivergent condition and because this was identified early she didn’t have to grow up masking her behaviour to fit in, and got the support she needed at college and university.

    Her inspiration for entering the world of architecture came early on during a workshop at her school. An architect wanted to hear their ideas about an aquarium that was being proposed in the town. When it was built, she went on a school trip to see it, thought it was atrocious and that she could do a better job herself!

    Throughout her education and architecture training she was drawn to inclusive design, which includes designing for disability, gender and religion, everything that’s considered a protected characteristic under the Equality Act. She now specialises in neurodiverse, inclusive design and nonvisible disabilities; focusing on how we can design better for dementia, autism, ADHD and all the nonvisible conditions, like epilepsy or chronic pain conditions.

    All architects and designers have a duty of care to the end users

    Under the ARB Code of Conduct all architects and designers have a duty of care to the end users, no matter what their religion, gender or disability. Knowing the needs of the people who will use a building is the most important thing. It’s an opportunity to address varying needs and tailor the space in better way.

    There are three neurocognitive profiles that each have differing sensory processing

    The three neurocognitive profiles are neurotypical, neurodivergent and neurodegenerative. All these profiles describe the way that the brain is set up, its instruction manual.

    The majority of people are neurotypical, but neurodivergent and neurodegenerative brains receive, process and label information in a different way.

    Our senses help us navigate our environments

    In addition to sight, hearing, smell, taste and touch, we have three extra senses that help us relate to the built environment.

    Proprioception – this is our sense of hand eye coordination, essentially where our body is in relation to itself.

    Vestibular sense – this is where our body is in relation to the space around us, so being able to sense movement, maybe in a lift moving up or down, or in a car speeding up or slowing down. It’s also the sense that causes car sickness.

    Interoception – this is the sense of what’s going on internally in our own body. So being able to sense if you’re tired, if you’re hungry, if you need to go to the toilet.

    We have probably experienced a temporary sensory processing difference

    If we are drunk, we perceive our environment differently. The speed at which we process is different, the way we speak, how we move, and think is different. Another example is a migraine. Lights may be really bright and sounds really loud, which is our brains processing that sensory information differently.

    Stephanie explains that some people with sensory processing differences may experience those things all the time, but it will vary from person to person. If somebody is autistic, they might be hypersensitive to sound, which is why something as simple as a hand dryer going off might cause distress. Visual processing is often different; colours might be perceived as significantly more intense or any high contrast patterns might look like they’re moving so for some people it might look like an optical illusion all the time.

    There is no such thing as one design solution fits all

    Stephanie says we have a stereotype of autism based on films that show a nine-year-old boy rocking in the corner, who screams if you touch him. Although there will be some people that match that description, autism presents itself differently in each person, with individual sensory needs. This makes designing spaces for the public difficult as it becomes impossible to cater for everyone’s individual needs, so instead we design for the majority of neurodivergent people.

    Fixed elements should be muted, natural and calming

    By using lower chroma colour palettes we can create lower sensory environments for the primary surfaces. Things that you can’t change easily, like walls and floors, should be as muted and as natural and as calming as possible. You can then add in boldness, in removable features, things that can be changed easily, like a multi-coloured zigzag rug. You can still have feature colours and design elements if you keep them at a lower chroma intensity.

    Needs can even change during the day

    Stephanie points out that an individual’s needs may also change during the day, with more energising spaces perhaps needed in the morning and then a more calming space in the evening.

    Two people sharing one space may have conflicting needs

    When designing spaces another consideration is hypersensitivity and hyposensitivity. For some people an environment can be over-stimulating, whilst for others they may require more stimulation.

    “As an autistic person, I need complete silence to work, but my brother has ADHD and he is the exact opposite. He can’t concentrate if a room is silent, so if he goes to a cafe where there’s background noise.”

    Similarly, some people may require absolute silence to sleep, whereas others need to play music or have some background noise to help them sleep.

    We can design for most senses

    After our visual sense, smell – or our olfactory sense – is the most powerful in terms of way-finding and navigation. It is possible to design for this sense too. For example by planting scented flowers at different ends of a building, the prevailing winds will carry those scents through.

    It is much harder to design for taste. Some autistic children or people with dementia may want to explore their sensory environment by putting things in their mouths. By using low VOC paints and non-chemical materials we can make sure they come to no harm. Similarly with landscape planting, avoid anything that is toxic to humans or animals.

    Your home is one space that can be designed to your individual needs

    The one space you can control is your home environment. Stephanie shares her preferences, although she stresses that someone else with autism might want something completely different.

    When working she cannot stand any noise whatsoever, so her office is soundproofed. She controls the light levels and glare from intense light with light filtration blinds as well as blackout blinds. She has colour-changing lights and individual thermostats in each room to control the temperature depending on her needs.

    All the colours she uses are low chroma, with a lower intensity than ‘brilliant white’. Each of her rooms has a different approach depending on the type of energy she needs for that space. When she’s cooking, she needs high energy so having a more energised space helps her.

    Sometimes simple measures can improve soundproofing

    Stephanie’s own house was built in the 1960s and needed updating. She started by insulating the ground floor, using mineral wool in the sub-floor. Her office has a separate acoustic lining that she put in using acoustic insulation boards.

    There are, however, a few simple solutions that can transform the acoustics of a room. Stephanie suggests changing the floor finishes and putting up acoustic noticeboards. Rubber underlay, for example, is more soundproof than other types of underlay. Check out the noise reduction rating of each product. Typically, anything that reduces the sound by 14 decibels or more is going to be a significant improvement. You can also add acoustic absorption through soft furnishings and floor-to-ceiling thick curtains with linings. If you want to go further you can add another wall lining to the existing wall with a small stud frame that you fill with acoustic insulation.

    Consulting people with ‘lived experience’ is really useful

    It’s important to understand how many different conditions exist and that it’s impossible to know them all. Therefore in Stephanie’s role as a Inclusive Designer, whenever she meets somebody with a disability that she’s not encountered before, she asks them about what would make the environment better for them.

    Asking the right questions is important

    Meeting people with lived experience of having a specific disability or characteristic is always the best way of learning. Find out about their day-to-day needs, what they find challenging, what they would like to be improved, and so on. Then it is up to the architect to work out how to design the space to suit that client.

    Building regulations don’t go into much detail to allow things to get built

    Stephanie says that the building regulations are broad and general, because if they were too onerous, it would be difficult to get things built. The main criterion is that all people should be able to use all parts of a building. Everyone should be able to access it and operate everything within it in the same way. That means disabled entrances shouldn’t be put round the back of the building or windows have controls that require two hands to operate them. Touch screens and app-controlled devices for lighting controls are all beneficial.

    Part M of the Building Regulations provides a guide on how to achieve this accessibility but it’s limited. Guidance BS 8300 is significantly better as it provides more detail, including the difficulties people have with certain things. For example, rather than it just telling you put an oven at 900 to 1000 mm off the floor, it tells you why you need to do that.

    PAS 6463 is a guidance document specifically about neurodiversity and designing for neurocognitive and sensory processing differences. It provides a lot of detail on the issues for people but doesn’t tell you how to fix them. It’s then left to the designer to come up with a solution.

    Social media can help you connect to people with lived experience

    Stephanie’s top tip is to speak to people with lived experience, because that will be so much more enriching and insightful than consulting guidance documents. Social media is a great tool to help connect with people who have specific conditions and are willing to share their experience. Search using different hash tags.

    We could all do better in our approach and the language we use around this topic

    Disabilities can be dynamic so on some days a person might need a walking aid, or a wheelchair and then on a different day, they might not be using anything. It doesn’t mean they were faking their condition on the other days. This also applies to neurodiversity, where people can have really good days and really bad days.

    Stephanie says that ‘disability’ and ‘disabled’ are not bad words, and we don’t need to avoid saying them. We need to acknowledge that disabled people exist, that they are living in a world that is not designed for them. Typically, disabled people are disabled by the environment, because if the world and all the buildings were set up to be inclusive for everybody, there wouldn’t be as many problems with using the built environment.

    Finally Stephanie asks people not to say ‘people are suffering with an illness or condition’. Stephanie definitely doesn’t feel she is suffering; she’s having a great time!

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    Floyd Slaski Architects

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