Contact →

Tag: Passivhaus Plus

  • 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

    Download a transcript of this episode.

    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.

    Please connect with us

    Subscribe, rate and review us on Apple Podcasts

    Follow Ben Adam-Smith on LinkedIn

    Follow Ben Adam-Smith on Bluesky

  • 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

    Transcript

    Download a transcript of this episode.

    Please connect with us

    Subscribe, rate and review us on Apple Podcasts

    Follow Ben Adam-Smith on LinkedIn

    Follow Ben Adam-Smith on Bluesky

    Join The Hub to access our in-depth video case study of Buckinghamshire Passivhaus, a PH15 build

  • HPH317 : Getting ambitious with sustainability – with Kit Knowles from Ecospheric

    HPH317 : Getting ambitious with sustainability – with Kit Knowles from Ecospheric

    Kit Knowles from Ecospheric explains why he is driven to keep pushing further in pursuit of sustainability in building projects.

    Kit Knowles (Rick McCullagh)

    Interview with Kit Knowles

    Despite his university education and early working life being in the field of chemical engineering, Kit quickly realised that this wasn’t for him. So, around 14 years ago, he committed instead to renovating and decarbonising a newly acquired 1909 arts and craft dwelling while he considered the direction in which to move his career forward.

    The SuperHomes network and trade shows provided information and inspiration

    Kit took an external wall insulation approach to his property and came up with a detail using three layers of Spacetherm with a PIR backing board. This would keep the profile relatively slim and maintain the aesthetic of the facade.

    The Thorns (Colin Poole)

    In order to fully research his proposed methods, he gathered information from attending trade shows and visiting homeowners of SuperHomes. SuperHomes is run by the National Energy Foundation, and is a charity that permits homeowners to join the network if they are able to reduce their home carbon usage by 60% or more. They are then able to open up their homes to share their methods for other people to reapply the solutions to their own properties. Kit credits SuperHomes with putting him in touch with a network of people where he could find out what others were doing, what they weren’t doing, and how he could push it further.

    Getting hands-on in the project working alongside his team of builders meant that Kit had a great insight into specification details and why they were often flawed when it came to installation, thus leading to a performance gap.

    The Thorns (Colin Poole)

    He started his business off the back of his own renovation project

    When Kit opened his own home as part of the SuperHomes network, he realised there were a large number of problems that he had solved, that other people hadn’t. So when he had five or six people asking for his help in explaining how he had done it, he decided to establish his own consultancy, although it did take him another few years to master the dark art of timber and damp!

    The Thorns (Colin Poole)

    After several years of chasing larger and larger projects, Kit came to two uncomfortable points of realisation:

    1. The full decarbonisation of the planet was never going to be impacted by what he was doing, given the scale on which he was doing it.
    2. That those that were doing the most carbon damage were those that were the biggest consumers.

    Clients can dilute the environmental ambitions

    Coming in late to a project is problematic because many decisions have already been made and there is little desire to start over. On one particular mansion he was not able to have any impact on the design of the house and his only option was to look to renewables for efficient energy generation.

    He had however managed to keep everything on a single-phase power supply rather than a three-phase… until at the last minute the client decided they wanted to heat the stair treads, which could only be done with direct electric, resulting in tipping the whole system over!

    Aesthetics matter

    From that point, Kit focused on how to develop more meaningful decarbonisation projects, and key to this were his interactions with Kevin Anderson from the Tyndall Centre. His advice was based on the iPhone effect of creating something that people didn’t know they wanted or needed, and then when they had it, couldn’t do without it. The only way to do that was to have full control over these builds and treat them as demonstration projects.

    And so the development arm of his business began, kicking off with Zetland Road. It was everything they had learned up to that point, put into a single project to see how far they could go. Despite not chasing Passivhaus certification, they ended up with Passivhaus Plus, together with eight world firsts.

    Zetland Road before renovation
    Zetland Road after renovation (Rick McCullagh)

    “Here, we were trying to get the combination of the technology with the look and feel. If it’s a bland Germanic box, it wasn’t going to revolutionise anything. It had to be old, it had to feel authentic and original. And it also needed really to be pretty sexy.”

    Rear lounge construction
    Dining/Living space (Rick McCullagh)
    MVHR ducting in chimney void
    Rear facade construction
    Zetland Road completed rear (Rick McCullagh)
    Zetland Road kitchen/diner (Dug Wilders)
    Zetland Road master bedroom (Rick McCullagh)

    By hitting the largest sectors they could make the biggest carbon impact

    With the construction industry being the largest contributer, at 40% of the country’s carbon emissions, Kit wanted to narrow down further into where the biggest carbon reductions could be made. With existing buildings being 80% of that amount, they could keep breaking that down further to select the projects where they could make the most impact. Of particular interest to him were the around half a million or so Grade II listed buildings.

    Kit uses a three level approach:

    1. Passive design techniques (ie orientation, glazing ratios etc). Thinking about how to use something differently, and using a quality roadmap to get as much for free as possible, such as free energies, or conservation of energy.
    2. Fabric. The idea that you can improve on airtightness and insulation levels throughout the building.
    3. Efficient or renewable energy. With the priority being numbers 1 and 2, hopefully there is little need for this.

    Lymm Hall is giving him the chance to trial new approaches

    Kit considers himself an opportunist, so when the chance came to purchase the Grade II listed, moated, 1570 country house of Lymm Hall, he and his family relished the chance to take the project on. It also came with a paddock that had planning permission for five detached new builds.

    Lymm Hall (Lymm Photographic Society)

    Their initial modelling estimated the energy usage would be around 470 kilowatt hours per square metre to heat to 20C all year round!

    It doesn’t cost anything to think how something could be done differently

    Trying to reduce that as far as possible has led to some fascinating innovations, such as developing a method where you can co-pressure test just one room (using the Pulse method) which means you don’t have to test the whole building. This means they can tackle different rooms in different ways and compare directly what their performance is like. For example, some floors they’ll be able to use underfloor insulation, whereas others are decorative floors that are protected under the listing so can’t use that approach. This should give them the ability to treat the areas in different ways and have a scientific method of comparison.

    “For the first time, we’ll actually have granularity over which components of upgrading a building made the most significant difference, because up until now, as a consultant, I can say, well, if you combine all these things together as a holistic approach, you will go from x to y in terms of performance, but what I can’t say is specifically out of those 10 things we do to your building, which is the first and the second and third most effective. It’s very, very difficult to get that granularity which this will offer.”

    Lymm Hall (Lymm Photographic Society)

    Achieving Passivhaus Premium on multiple dwellings will be a world first

    Alongside the main Lymm Hall project, they are also building their five detached houses in the paddock using modern methods of construction without any petrochemicals or concrete, with the ambition of achieving the Passivhaus Premium standard. There aren’t currently any Passivhaus Premiums in the UK, and to achieve five on the one site would be the first time that has been done anywhere globally.

    Another project is a series of barns that they are converting for ecotourism and making completely off-grid for water, electricity and waste.

    They are also working on an old sorting office in Levenshulme where they are trying to create the world’s first zero waste, zero energy food hall. It will have multiple kitchens, restaurants, brewery, roastery and zero waste deli.

    Kit is very aware that agriculture is also one of the largest contributers of carbon emissions, and is working alongside clients to do a lot of work around food and energy. This is around agroforestry in the main, looking at building products and food production, and also large scale energy production from estate lands.

    Find out more

    Visit the website of Ecospheric

    Follow Ecospheric on Twitter

    Transcript

    Download a transcript of the interview with Kit Knowles

    Please connect with us

    Subscribe, rate and review us on Apple Podcasts

    Rate and review the podcast on Stitcher

    Like our Facebook page

    Follow us on Twitter

  • HPH280 : A beginner’s guide to the Passivhaus Standard – with Jon Bootland

    HPH280 : A beginner’s guide to the Passivhaus Standard – with Jon Bootland

    Chief Executive of the Passivhaus Trust, Jon Bootland, explains the processes and benefits of building your house to the Passivhaus Standard.

    Interview with Jon Bootland

    When Jon Bootland finished his university degree he began his employment first as a building services designer, and later working on good practice for sustainable low energy buildings, now with nearly 30 years experience. He has also been involved with the Passivhaus Trust since it was formed back in 2010. With initially very slow progress since the first Passivhaus was completed in the UK in 2010, numbers are now increasing rapidly at around 1,200 completed buildings (of which around 200 are individual owner-occupied homes), with another thousand already in the pipeline.

    Carrowbreck Meadow – Image copyright Jefferson Smith

    There’s nothing hugely complicated about Passivhaus

    The origins of Passivhaus come from Germany, where the physicist Wolfgang Feist wanted to find a way of making sure that high performance buildings actually delivered on their claims, and performed the way that they were designed to do.

    “It’s all about building physics. There’s nothing hugely complicated about it. It’s just what do we need to do to actually make it work and do what we said it was going to do.”

    High in comfort levels, low in energy use

    The fundamentals of a Passivhaus are:

    Insulation – This is an important part of reducing the energy required to heat the building. A typical Passivhaus might have up to 30cm of insulation, meaning that the walls will be very thick.

    The building fabric and airtightness – The other parts of the building will also need to have a very high performance. Windows for example will need to be triple glazed with good quality frames and careful detailing about how they fix together. The airtightness of the building is important with the aim being to stop draughts coming in and heat leaking out.

    Ventilation – Because the building is now free of draughts, attention then needs to be paid to how to ventilate it. A mechanical ventilation system is used (MVHR) to bring fresh air into the building, while recovering the heat from the outgoing air.

    As well as dealing with keeping the house warm in winter, Passivhaus formulae also look at the sun and other heat sources coming into the building and how the ventilation and insulation can work to keep it cool in the summer.

    Old Holloway – Image copyright Juraj Mikurcik

    Have a Passivhaus expert in your team

    Jon says that building a Passivhaus is harder to do than a normal house, but that doesn’t necessarily mean you have to employ a team of specialists. He would however recommend having someone in your team that does have Passivhaus training, and preferably experience. It doesn’t have to be the builder, but could be the architect or a consultant.

    The Passivhaus Planning Package does the calculations

    You will need someone who knows what they’re doing to fill in the Passivhaus Planning Package (PHPP) and work out the answers to the calculations with you. It is a tool that takes a holistic approach to making all the elements work together, to make sure you end up with a building that has the performance and comfort that you are looking for.

    There are benefits to having certification

    PHPP should be used right from the beginning to look at the size and shape of the building, the window locations, balconies or anything else that might penetrate into the building etc. A certifier is able to check what is being put forward and advise on whether what you’re suggesting is actually going to work in the way it is intended.

    Without having a certifier on board you will not be able to call it a certified Passivhaus, which does have some value in being able to sell the project. Certification is the best way of ensuring that your building will meet the required standards and provide the comfort and energy performance that you are looking for. If you’re not planning to use a certifier, then Jon recommends ensuring your team of architect, builder and consultants have plenty of Passivhaus experience between them to give you confidence it will perform as intended.

    There are health and cost benefits

    Jon outlines some of the key benefits of a Passivhaus:

    Lower energy bills – The extra insulation and airtightness means less heat is escaping from the house, and therefore less energy is needed to heat it. Typical heating bills for a standard sized Passivhaus might be around £100, compared to several hundred for a non-Passivhaus equivalent.

    Health benefits – Jon says there are research projects planned in the next few years looking into this, but there is still plenty of anecdotal evidence from occupants talking about the health benefits of living in a Passivhaus. As well as thermal comfort, the air that comes in can filter out air pollution and pollen, and people have reported improvements in asthma conditions. The mechanical ventilation also reduces moisture levels in the building which prevents condensation and mould.

    Some construction methods will be harder than others

    Jon says that although you could achieve Passivhaus with any construction type, it will be harder to achieve with brick and block for example than with timber panels. Although it’s possible to do, it will just need to be approached differently.

    The extra outlay is money well spent

    Jon uses social housing to get comparable benchmarks for how much more a Passivhaus will cost to build over a standard form of construction. Typically the additional cost of building a Passivhaus will be around 4-8% higher. Jon says that probably half of that is just on better quality building, which actually should be applied to all new buildings anyway, regardless of whether they’re Passivhaus.

    So on a £200,000 – £400,000 build cost, that’s likely to add on just £8,000 – £16,000 extra.

    “So, say you’re going to get a much better quality building that will make you more comfortable, more healthy and will perform better for 50, 100 years or more, it’s a very small amount of money in my book and it’s a much better way to spend your money than on a super flashy designer kitchen.”

    There are ways to keep costs down

    The shape and form of your building is crucial in keeping the costs down. Adding on multiple wings, outlying parts, differing floor levels, balconies additional roofs, lots of corners and odd shapes, will all make it more difficult to make a Passivhaus work, and will be more costly.

    Jon wouldn’t recommend everyone try and build a square box as being the answer, but the closer you aim to a square box shape the easier it is to achieve Passivhaus.

    Another way to keep costs down is to bring in your Passivhaus expert as early as possible. Don’t wait for the design to be finished and then call them in to do the calculations, but involve them at the design stages to help develop the building shape, window sizes and locations etc.

    Multiple heating sources are not needed!

    Jon explains that it can be challenging mentally to think of a house not needing multiple heat sources in it, but really they’re not needed.

    Commonly though, people might put a radiator by the front door so that as you walk in there is a perception of extra warmth, while your body adjusts from the cold outside to the comfortable 20-21 degrees inside. A heated towel rail in a bathroom is also quite popular.

    The design needs to minimise overheating risk

    With homes becoming more energy efficient, the risk of overheating in the summer is becoming more significant and has to be planned for.

    The main source of heat coming into the house in the summer will be from the sun, mostly in the late afternoon and evening. To stop the heat coming in without losing the views, Passivhaus buildings will often have some kind of shading or overhang on the west or south facing walls which keeps out the heat until later in the evening when the temperature drops.

    There are also other heat sources to take into account such as the occupants and appliances, which heat the house slowly during the day. This data also feeds into PHPP to calculate how much heat will need to be taken out of the building to keep it cool. This can be done using the mechanical ventilation, or by opening the windows, particularly overnight. The temperature fluctuation in a Passivhaus will only be a few degrees, compared to 10-15 degrees in other houses.

    “But the extra insulation and the extra performance of the windows, the doors and so on helps in the summer. Just as much as it helps in winter in keeping the heat in, in the summer it keeps the hot air out.”

    The Passivhaus Trust oversees the standard in the UK

    The standard was invented and developed in Germany, but in the UK it is looked after by the Passivhaus Trust. Their job is to look at how to apply and make the Passivhaus work in the UK, with our differing weather patterns and culture. Jon gives an example of these different considerations being parts of Scotland, where people don’t want to open their windows for night-time cooling because of midges coming in, so different approaches have to be developed.

    The second aspect to their work is promote the adoption of the standard, by engaging with central government, local authorities and trying to get people on board.

    Jon accepts that while it’s a great standard it’s not perfect, so the third part of their work is carrying out research on specific aspects that can be changed and improved over time.

    There are different levels of Passivhaus standard

    There are two main standards: Passivhaus Classic for new build and EnerPHit for refurbishment. The criteria for achieving EnerPHit are slightly less stringent because it is that much trickier to do a retrofit. Certain aspects of the building are fixed and can’t be changed, so an allowance is made that if you can’t change those things you can still get Passivhaus.

    The Barrel Store – an EnerPHit Standard youth hostel. Image copyright Mac McClure

    In addition there are also two new standards: Passivhaus Plus and Passivhaus Premium, which are effectively the Passivhaus Classic but with renewables. Passivhaus Plus is where the energy generated by the renewables will exceed the energy demand of the house and reach zero carbon. So the energy generated will be equal to or more than your energy used during the year.

    Passivhaus Premium takes that a step further with enough renewables to create an energy positive house, so you’re generating more than you need and reclaiming money back from the grid.

    PHPP can be used to calculate embodied energy

    Within the planning tool they are now looking at add-ons which consider the embodied energy of the materials that you use and form part of the Passivhaus calculations. This will benefit people who are keen to use natural materials or who are just interested in understanding how much embodied energy there is. Jon stresses it is not a requirement for achieving the standard, it’s just developing the capacity to do it for those that would like it.

    Find out more

    Visit the Passivhaus Trust website, and learn more about their Passivhaus goes Personal campaign

    Transcript

    Download a transcript of the interview with Jon Bootland.

    Please connect with me

    Subscribe, rate and review the podcast in Apple Podcasts

    Rate and review the podcast on Stitcher

    Like our Facebook page