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  • HPH352: Encouraging and supporting home retrofit in your local area

    HPH352: Encouraging and supporting home retrofit in your local area

    Neighbours Wookey and Rob Leedham explain why they were motivated to retrofit their homes, how they built up knowledge and why engaging with others on a similar path has been extremely useful.

    Interview with Wookey and Rob Leedham

    Neighbours Wookey and Rob Leedham share their experiences on their individual retrofit journeys. With technical minds and a passion for problem solving, this pair of DIY retrofitters have undertaken a vast range of tasks, from installing external wall insulation (EWI) to building a ground source heat pump! In the process they have saved a lot of money but we look at why they were well suited to this DIY approach and the value that they have taken from networking with fellow retrofitters (through green building organisations such as the AECB).

    Wookey’s retrofit

    Wookey’s journey began when he and his wife bought a house in Cambridge that initially looked presentable and tidy. However, it was draughty and not particularly comfortable and soon they decided to retrofit it. Having hired builders in the past and not been completely satisfied with the standard of work, Wookey decided to undergo the renovations himself.

    Wookey’s house before retrofitting
    Wookey’s house after retrofitting

    The existing dwelling is a 7 x 8 metre square, 1960s detached house with a separate garage. During their renovations they began by insulating the loft and replacing the front door. They then continued on to wall insulation, both internal and external in different parts of the house. This was followed by replacing the old and inefficient boiler, which is now also about to be upgraded to an air source heat pump and eventually replacing all of the windows. Furthermore, Wookey chose to build an extension that connected the house with the garage and added a sun room.

    Extension before
    Extension design
    Extension After

    As the existing house is masonry cavity wall construction Wookey decided to keep things simple and construct the extension in the same way. They did hire a builder to put up the superstructure but Wookey undertook all the internal work, fitted the underfloor heating, tested the airtightness and even learnt how to fit an air source heat pump.

    This DIY approach has been time consuming, with it coming up to a decade of renovations. However, it has also allowed them to save a remarkable amount of money.

    “I learned quite a lot from having done it mediocrely once [renovating his previous property] and going, right, this time we’re doing things properly.”

    DIY allows you to control the quality of the work

    DIY projects can be stigmatised as below a professional standard, but Wookey explains that DIY has enabled him to get a much better finished product. After some bad experiences with builders cutting corners, Wookey found that doing the job himself allowed him to get the standard he wanted and all the details correct.

    In Wookey’s experience, the nature of the building industry means that the right way is considered to be the one that gets the job done in the fastest time.

    “The real problem with tradespeople is that everything’s time based. How many hours is this going to take? So they won’t necessarily thread the plumbing or the wiring in the right place, they’ll do whatever they can get at in half an hour, rather than doing it properly which is literally going to take 10 times as long. I think that’s the main advantage of doing things yourself is you get those little details right.”

    Having a long-term plan for your retrofit is essential

    It is commonly recognised that an over-arching retrofit plan is very important to ensure a successful project, mainly because it will help to avoid having to retrace steps or undo your work. DIY retrofits can take a long time and if you choose to live at home during that time, it will likely happen bit by bit or one room at a time. For example, replacing your windows without considering how it links up with insulation may be a missed opportunity.

    Addressing a thermal bridge at the front door
    Solar PV

    Modelling your home in PHPP is invaluable

    Wookey also decided to do the energy modelling for his home himself. Initially he was reluctant to use PHPP but discovered that it was fairly straightforward and offered a lot of benefits. It is a great tool for retrofitters as it helps you plan your retrofit, predict the potential performance of your house and identify what is needed in order to reach a given outcome. Sarah Lewis from the Passivhaus Trust helped us break down the topic of PHPP, providing an in-depth explanation of the benefits and sharing her own experience on a retrofit journey.

    “I put PHPP off for a long time, because it’s a pain in the arse and it took a month from a standing start, even though I kind of understand the principles. But you know, it’s just if you’ve not done it before, it’s hard. But then you realise, actually, we could get to EnerPHit or at least pretty close on this house.”

    You will need a certain set of skills for a DIY retrofit

    Wookey’s background is in software engineering and he has always been interested in fixing his own cars. This meant that shifting his mindset to building physics wasn’t too difficult. Wookey advises to anyone starting out on this journey to spend the time learning the processes and discovering the how and why. Wookey admits that it can be a bit difficult to find this information online, but the Denby Dale Passivhaus study is a great place to start as they provide clear examples of where techniques have worked. This is also why retrofit and self build communities such as Cambridge Carbon Footprint, Cosy Homes Oxfordshire and The Hub here at House Planning Help are amazing resources that allow you to ask questions and learn from experts or others who have already been through the process.

    “I’ve got a fair amount of practical skill. I’ve always fixed my own cars and that was where it started… and electronics. Buildings are quite simple in comparison to cars and electronics! It’s often fairly basic stuff. It’s mostly a matter of understanding building physics.”

    There is a shortage of green builders in the UK

    Wookey explained that in the Cambridge area and many other parts of the UK there is a real shortage of tradespeople who are experienced in sustainable construction. Hopefully this will change over time as demand grows and the industry comes to understand the need for attention to detail. In the meantime this might be another reason why a DIY approach is preferable.

    External Wall Insulation (EWI)
    Eaves insulation

    Some areas are worth paying the professionals

    Tiling and plastering were two areas where Wookey decided to bring in a professional because they both require a level of practiced skill in order to achieve a good quality outcome.

    Wookey also paid £1500 for some drawings for his extension, but did end up regretting this as they designed a standard box that didn’t consider energy efficient principles. As a result, Wookey ended up drawing his own plans and only used the plot measurements from the initial drawings to aid his own design. This offered him the freedom to create exactly what he wanted, however there is an added pressure to this and if things are calculated wrong then that is your responsibility.

    “Generally, my assumption is that I can do everything, and it turns out that’s true for everything… apart from plastering, that’s the hardest thing in the world.”

    DIY retrofits can be all consuming, it is important to maintain a balance

    A DIY retrofit can be a long and time consuming process. For Wookey, the challenges and puzzles are enjoyable, but they can become all consuming if you are not careful. Wookey and his wife decided early on that at least one weekend a month they would do something other than DIY to ensure that they maintained a good balance. Wookey also highlighted that it was easier to give so much attention to their retrofit as they don’t have children and the commitments that come with family life.

    Guy Hargreaves employed a contractor to carry out his retrofit. Watch our in-depth video case study in The Hub.

    Many people are interested in retrofit but not the DIY approach

    Since undergoing his own retrofit Wookey has encouraged family, friends and colleagues to consider taking on their own projects. While they understand the potential benefits a retrofit can deliver they do not always warm to the DIY approach! So, you can of course bring in a contractor to do the work.

    DIY retrofits are a great option for people who have a passion for doing the manual work, enjoy learning and have plenty of time available.

    “A surprisingly large fraction of the people I meet, think, yes, that is a good idea and I should definitely find out about it, a very small fraction of them want to do it as DIY or take ownership, they don’t really want to learn about the whole thing. They just want somebody to do it and there’s a terrible shortage. There aren’t enough people around here at the moment. I know several people who’ve been quite keen, and have tried to get quotes and struggled or been told that we can come and get to you in two and a half years time.”

    You will begin to notice the benefits

    Wookey explained that as well as the obvious benefits of an energy-efficient house being cost effective and warmer, they also began to notice small things that improve their daily life. For example, when you achieve a good level of airtightness and have triple glazed windows it becomes more peaceful. Also dust mites disappear when the MVHR is running and keeping the home within an optimum humidity range.

    “When you go and rent somewhere to stay, you go to these cold and draughty rented cottages. And you think it’s not like my nice house at home. So you get quite picky about buildings once you’ve tried living in one that’s actually good.”

    Rob Leedham’s retrofit

    Wookey’s neighbour Rob Leedham has also been gradually improving his home. Rob and his family have lived at this house for 23 years and although he had no grand plan at the beginning, he has been consistently adding one green measure after another.

    Rob has undertaken the whole of his retrofit as a DIY journey, including installing 150mm of External Wall Insulation (EWI) on all external walls and insulating the footings of the house. Rob is also passionate about solar power and energy generation. 12 years ago they installed solar PV panels on the roof and have more recently hooked it up to an inverter that will be able to accommodate both additional solar panels and batteries for energy storage.

    Community access to airtightness testing kits will help make the retrofitting process more affordable and more accessible

    One of the trickiest parts of retrofit is reducing the air leakage of a property, which calls for a good airtightness strategy. Having the airtightness layers all in place is not enough – the airtightness needs to be checked and then further leaks can be identified and addressed.

    Rob showed Ben two fans that can be used for testing. One is a professional blower door kit and the other is a homemade version. These can loaned to other retrofitters in the area. A standard airtightness test is time limited and will cost around £300. Rob’s hope is to get a few for their group in Cambridge so that retrofitters can take their time to achieve the best airtightness results possible and not feel like they need to rush on.

    Using their airtightness kit, here are the current findings for both Rob and Wookey:

    • Wookey had aimed for below 1 air change per hour (at 50 Pa) and is currently measuring at 1.52.
    • Rob had aimed to get his below 3 air changes per hour and is currently measuring a 2.1.

    Rob’s DIY blower door kit!

    Rob built his own ground source heat pump

    Rob is also technically minded and opted to build his own ground source heat pump from scratch.

    “The thing about ground source heat pumps is that they are actually very simple. There’s a compressor or an expander, and a pump and two heat exchangers. That’s basically it. So it’s not that hard to build your own. Some parts of it are inside and some parts outside. And so the electronics is inside and the header tank. And there’s a little display there that says it’s got a coefficient of performance of 4.4 at the moment. So inside, we’ve got that part that calculates the efficiency. And there’s a little electric meter, a standard electric meter for measuring how much electricity is used. It’s been going for about two years and a couple of months, and it’s up to four megawatt hours of electricity in to provide all of the heating and hot water for those two and a bit years.”

    The key to heat pumps working efficiently is a well insulated house that doesn’t need much heat.

    Rob does not recommend this route however unless you really enjoy the process and recognises that the sensible choice is to buy one and have it installed by a professional!

    Stuart Dyer’s retrofit

    Stuart Dyer is another member of the Cambridge retrofit community and has been retrofitting a 1930’s detached property. Stuart took a different approach and moved out for a year whilst they carried out an extensive retrofit. The process included external wall insulation, triple glazing, fitting mechanical ventilation with heat recovery (MVHR) and installing an air source heat pump. Stuart highlights that one of their biggest challenges was get their airtightness to a good standard and they worked quite hard on this area. They also put in underfloor heating, which works well with the air source heat pump, and insulated quite a lot under the floors.

    Stuart likes being in Cambridge because there is quite an active retrofit scene, consisting of monthly meet-ups of the Association for Environment Conscious Building (AECB) (that Wookey organises). This offers a great chance to meet with people in the pub, discuss with those who have already done a lot of work, the good things to do and the pitfalls to avoid. Transition Energy Group is also quite active in terms of new technologies, new interests, and there is a lot of good advice there. Cambridge Carbon Footprint have lots of great case studies and also runs an Open Eco Homes each year where you can visit other people’s houses, whether they are new build Passivhaus or up to EnerPHit standard.

    Search for ‘green building’ meet-ups in your area

    In every town or city there will be opportunities to network with like-minded individuals and professionals by tapping into local green building groups. These are often as much about inspiration as sharing knowledge but it’s particularly useful for those on a DIY journey who may encounter challenges and be looking for advice or contacts.

    Find out more

    Cambridge Carbon Footprint

    Green Building Forum

    Open Eco Homes

    Association for Environment Conscious Building (AECB)

    Transition Energy Group

    Cosy Homes Oxfordshire

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  • HPH323 : Can I heat my home with an air source heat pump? – with Nathan Gambling

    HPH323 : Can I heat my home with an air source heat pump? – with Nathan Gambling

    Influential podcaster and heating systems expert, Nathan Gambling, explains why choosing the right installer is even more important than selecting the heat pump.

    Interview with Nathan Gambling

    Nathan comes from a family of heating engineers and he followed suit, completing his apprenticeship with the MOD in 1991. In 2006, he started teaching, including running City and Guilds courses in a prison, before also teaching in colleges.

    With his unique background in heating systems and teaching, Nathan now runs the BetaTalk podcast; a highly respected source of content and information for engineers and those interested in the heat pump industry.

    We teach people to be qualified, not competent

    This is Nathan’s assessment of the vocational education system in the UK. Having come out of that, but still wanting to facilitate learning, he got into podcasting where he was able to use his skills and connections to disseminate and amplify the voices of quality heating engineers. He is a firm believer that the starting point of any installation should be finding a competent engineer, but this isn’t always straightforward for a homeowner or self-builder to identify.

    Using a quality engineer should be a priority

    Heating is a complicated business, yet anyone can set up a plumbing company without any qualifications at all (unless you’re also dealing with gas, which would need the necessary certification). As an engineer, you don’t need certification to install a heat pump, unless you’re doing it under the Microgeneration Certification Scheme (MCS) which is where you’re getting a government grant. Something to be mindful of, is that the MCS accreditation applies to the company, rather than an individual engineer, so it could even be possible that that person has left!

    According to Nathan, the best engineers are those that engage in peer-to-peer learning and are constantly talking to each other about different techniques and best practice. These are the people that are on social media networks looking to learn from one another. It’s not just about training but familiarisation with what’s current in this quickly changing industry.

    Nathan says that the range and quality of heat pump units on offer, whether supplied by the HVAC world, specialist heat pump manufacturers or traditional boiler companies, are actually pretty similar. It’s having a good engineer that will be the difference and make the unit work very well.

    Heat pump technology exists all around us already

    Yet, much of this is technology that most of us wouldn’t even normally associate with heat pumps, such as in vending and slushy machines. We also commonly confuse it with air-conditioning, but actual air-conditioning is quite rare. The systems in place in office buildings, cinemas, and retail centres, are much more likely to be something called comfort cooling, which heats us as well as provides cooling.

    Heat can be extracted from even the coldest air temperatures

    Essentially, a heat pump is something that moves energy from an evaporator to a condenser, and uses vapour compression to do that. It uses a refrigerant to compress it and extract more heat.

    Unless you get down to -273.15 degrees celsius, which is the temperature at which atoms stop moving, you can extract heat energy. That energy is compressed, before being released out with a condenser.

    In most domestic situations this would be an air to water system, where you’re extracting the energy from the air and emitting it to the rooms via water running through radiators or underfloor heating.

    Your power demand changes according to the outside temperature

    All homes will leak, some more than others, and if there’s a temperature difference between indoors and outdoors, then heat will move.

    Systems tend to be designed to be able to cope with the average coldest day in the UK, which is around -3 degrees. Most homes need 8000 joules of heat per second to be able to maintain 21 degrees inside when it’s -3 degrees outside. That’s 8 kilowatts.

    When it’s 5 degrees outside it will need 5.5kW.

    When it’s 10 degrees outside it will only need 3.6kW.

    Your power demand is therefore constantly changing depending on what the outside temperature is, because heat will move more quickly if there’s a greater temperature difference between inside and outside.

    Unfortunately, most gas boilers work on fixed temperatures, whereas they need to be modulating their temperature around the radiators according to what the outside temperature is.

    The trick to getting a really efficient air source heat pump installation is to match the temperature that is flowing around your radiators as closely as you can to the temperature outside. So if it’s -3 degrees outside and you can maintain 21 degrees inside with 40 degree water in your radiators, that’s going to be more efficient than a system that is running 50 degree water around your radiators when it’s -3.

    “So if you design your system to be able to reduce that flow temperature in your emitters, for the colder temperatures, that’s when you start to see these really good what they call COPs – coefficient of performance.”

    The way to do that is with the size of the emitter. A good engineer will design a system that gives you the lowest flow temperatures possible for the coldest temperatures, which could mean both underfloor heating and radiators to increase the surface area.

    There are few constraints on where to site a unit

    Planning laws in England dictate that the external unit should be installed at least a metre from the boundary. Although they do make some noise, Nathan says they’re generally no worse than standard oil boilers or gas flues. However, it’s still wise to distance units from the neighbours’ windows.

    Some people aren’t keen on the aesthetics of the heat pumps on their properties so try and cover and disguise them. However, as the pump needs to extract air from the outdoors, you don’t want to be restricting its ability to do that.

    It is critical to size a heat pump accurately

    Too big and you’re paying too much for a system that won’t run efficiently. Too small and it won’t meet the energy demands of the home.

    Traditionally, heat loss calculations were used for sizing heating systems. These take data about the fabric of your home from SAP/RdSAP reports, so are more of a prediction about how it should perform, and assume that every square metre of your home is performing the same, which doesn’t happen in the real world.

    There are now new methods that can accurately measure the speed of heat going through your fabric. This heat transfer coefficient means you know what power you then need for any external temperature. Nathan says there are two different approaches that would achieve the same result.

    Veritherm – this is an overnight test that uses heaters to increase the internal temperature of the property, while fans distribute the heat around evenly. Halfway through the test the heating is turned off. Temperature sensors inside and outside record measurements throughout the night. The algorithm knows how much power has been used to heat the property and monitors the speed at which that heat leaves through the building fabric to give you the heat transfer coefficient.

    Heat Pump Survey – this uses several data loggers placed strategically around the home where they are left for three weeks. Their algorithm takes into account metred energy consumption along with weather data to give the heat transfer coefficient.

    So tools like this are incredibly useful when designing a heat pump system.

    Swapping a boiler for a heat pump may require infrastructure changes

    That’s not always the case and is something that will be individual to each property, but is often why a heat pump installation will cost more than just swapping out an old gas boiler for a new one. Switching to a heat pump may need new radiators and pipework.

    There is currently help for homeowners wanting to purchase a heat pump, with up to £5,000 being offered under the Boiler Upgrade Scheme.

    The boiler market has traditionally been incentivised

    This has meant that installers may have been incentivised with loyalty schemes, cashback, holidays etc by the big four manufacturers to buy larger systems than many homeowners would actually need.

    Nathan explains that a marketing tactic now being used with heat pumps, is advertising new refrigerants that can heat water to 60 degrees, which sounds great to customers. However, what’s not so great is that this will actually put up their electricity bills, because the most efficient way of running a heat pump is to get the lowest temperatures as possible around your radiators.

    There are key questions we can ask to help find a quality engineer

    • What flow temperature are you going to design my system for? – you want them to be saying the lower temperatures.
    • Do you weather compensate your heat pump systems? – they should be automatically adjusting the flow temperatures going around your emitters, according to what the outside temperature is.
    • What centres do you put your underfloor heating down? – you should really be wanting your underfloor down at 100mm centres as this increases the surface area and means you can run lower flow temperatures through it.

    Nathan’s final advice is to not get too caught up in researching the actual product and things like decibel levels and SCoP. SCoP is a theoretical prediction of the performance that each manufacturer will give in their literature. It doesn’t necessarily mean that it will perform like that, because again that will come down to the installation. Instead, focus mostly on working out who is doing good things in this space and is going to provide you with a quality system that will accurately and efficiently meet your needs.

    Read more about the Verithem method of measuring heat loss, and its uses, in our interview with Tom Fenton.

    Find out more

    Check out the BetaTalk podcast

    Follow Nathan Gambling on Twitter

    Transcript

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  • HPH279 : A beginner’s guide to building terminology – with Lee Fordham from Architype

    HPH279 : A beginner’s guide to building terminology – with Lee Fordham from Architype

    Lee Fordham from Architype simplifies some of the terminology you might come across if you’re thinking about doing a sustainable self build.

    Interview with Lee Fordham

    Shortly after qualifying as an architect in 2004, Lee spent time travelling and working for architecture practices in New Zealand and Australia. When he returned to the UK he decided to pursue his passion for sustainable design and started working at Architype, one of the UK’s leading sustainable architects, where he is now an Associate Director.

    A beginner’s guide to terminology

    For those that are just setting out in their self build journey there can be an overwhelming array of technical terminology used that can be baffling to anyone outside of the industry. Lee takes us through some of the common terms that you might come across in a sustainable self build.

    Passivhaus / Passive House

    Passivhaus (Passive House in the United States) is a building standard that was developed in Germany around 30 years ago. Using physics, the aim is to reduce the performance gap between how the building is designed to perform, and how it actually performs.

    The aim is to make the building more comfortable for the occupants and reduce how much energy the building uses, which is done with a better quality of build.

    Liz and Mike Hill’s Passivhaus – designed by Architype

    The experts will use the Passivhaus Planning Package (which you’ll hear referred to as PHPP), which essentially is a very complicated spreadsheet of data that allows them to design a building that will meet the Passivhaus criteria. The contractor will use that information to construct the building, and a certifier will guarantee the work and certify it if it meets the required standard.

    Passivhaus plaque

    MVHR

    You’ll commonly hear a Mechanical Ventilation Heat Recovery system referred to as an MVHR. They’re most likely to be used in Passivhaus buildings, but not exclusively. It is a ventilation system which extracts the used air from inside a building. It takes the heat from that air and mixes it with fresh air which is being brought into the building from outside, to provide every room with fresh, pre-warmed air.

    The air is filtered coming into the building, and different filters can be used according to whatever is in the external air in that area.

    A key benefit over natural ventilation is the element of control over any given space, ie removing moisture from bathrooms etc.

    An MVHR for a domestic dwelling is roughly the size of a combi-boiler and will need to be incorporated into the building’s design.

    MVHR unit at Landsdowne Drive Passivhaus – Green Building Store

    Foundations / Footings

    These will usually be designed by a structural engineer and are what sit under the building to evenly transfer the weight of the building to the earth. The type you use might be dependent on what your ground conditions are like, but some examples are pile foundations, deep strip foundations and raft foundations.

    U-value

    A complicated one to explain, but essentially it’s a way of measuring how thermally conductive a component or a series of components (like a piece of glass, wall or roof) is. It is the rate at which heat travels through. The lower the U-value, the better it is.

    The aim is to have fairly consistent U-values across all the components in a building. Having just one element that isn’t consistent could act as a magnet for moisture and potentially damage the structure. This can partly be achieved by better insulation, triple-glazed windows etc.

    The U-values form part of the data that feeds into the PHPP system.

    Airtightness

    At a very basic level, this is about eliminating drafts in a building. It’s relatively easy to achieve but needs to be thought about at the design stage. At Architype they denote the airtightness layer on their detailed drawings using a red line, which shows the contractors where to take particular care in the construction so as not to damage it.

    To meet building regulations, when the building is finished an air test will be carried out. The building has a giant fan attached to it and is either positively pressured, ie blowing air in, or negatively pressured, ie extracting air. The rate at which the air leaks gives you your air test result. It is a measure in pascals of the pressure of an internal area. Building regs require you to get a result of 10 or less.

    The method in a Passivhaus building is slightly different. This takes an average reading from the building being both positively and negatively pressured, to give an n50 value which is how many volumes of air changes there are in an hour. The Passivhaus requirement is that it should be less than 0.6, so significantly better than building regulations.

    Build system / construction method

    This is a way of describing what method you are going to use to construct your building. Examples include timber frame, masonry, brick and block, insulated concrete formwork (ICF), pre-cast concrete, in-situ concrete, and cross-laminated timber.

    Pre-fabrication

    Pre-fabrication is where components, or indeed whole buildings, are made off-site. This could be from wall panels, to timber frames, to bathrooms that are fully plumbed and tiled, to entire houses.

    MAKAR production facility

    You can even go to the factories and choose your handles, paint finishes, floor finishes etc. When they reach the site they are connected together. The advantages of building the elements off-site is it can be quicker, they’re not subject to delays or damage from the weather, and often it can result in better quality and working better when brought to site.

    Huf Haus

    Zero carbon

    Lee says that this is a difficult one to explain as there are many different interpretations of what it means.

    Generally it refers to off-setting the energy use in a building. So the better your building is, ie a Passivhaus, the less carbon you have to off-set because you’re not using as much energy.

    Looking deeper into it, some people will be referring to zero carbon in use, which is the energy that is used starting from the point of when it’s been built, through to its end of life.

    But there’s also embodied or sequestered carbon, which takes into account everything to do with the design and construction of the building, together with the in-use energy and sometimes through to the demolition. This is more complicated to account for, although there are tools which can help explain for instance, how much energy is used in getting a tree from Germany to the UK to use in a timber frame.

    Custom build

    Whereas self build has many decisions for you to make, whether or not you’re doing it in the purest sense of building it yourself, or whether you’re commissioning someone to carry that out for you, custom build can take some of those decisions away from you. There will be an offering from the custom build company, but with options for you to customise it. That could be in terms of the style of the house, the layout or the finishes. It might not be as individual as you would get with a self build, but it can take away a lot of the headaches!

    Potton Homes design

    Solar shading / brise soleil

    Effectively the same thing, brise soleil or solar shading would be used on the south facing side of a building to limit the sun coming in during the summer months when you don’t want the building to overheat, but allowing it to come in during the winter when the heat is required. Generally it would be a horizontal component that sits over the south facing glazing, whether that be a roof overhang, external canopy or series of louvres.

    External louvres – Charlie Luxton Design
    Wimbish Passivhaus Scheme – Parsons & Whittley
    Ditchingham Passivhaus Scheme – Parsons & Whittley

    On an east or west elevation you would usually have a vertical component, and that’s just to do with the angle of the sun at certain times of day and certain times of year. Windows on the east and west elevation can be harder for dealing with glare and overheating issues.

    Lee says the ideal situation is to have the building facing south where the solar gains can be controlled more easily.

    Design team

    The core members of a design team are likely to include: an architect, structural engineer, civil engineer, mechanical and electrical (M&E) engineer, and possibly a project manager.

    Beyond that, depending on your site and your level of involvement and interests, you might also have: landscape architect, ecologist, arboriculturist, quantity surveyor, Passivhaus designer etc.

    Renewables

    Renewables refers to technology that generates energy. This could be photovoltaics, wind turbines, hydro power etc.

    Air source and ground source heat pumps

    An air source heat pump takes energy from the temperature in the air. Any air above zero degrees has energy in it and this can be taken and transferred into heat or hot water for your house. Similar in size to a washing machine, they’re put on the outside of a building.

    The ground source heat pump works in much the same way but will take the energy from the ground. They have pipes which can either be spread horizontally in the ground which will require a lot of space, or as a vertical spread of pipes, which need less space but are a lot more expensive.

    Plans, elevations, sections and details

    These are examples of the different types of design drawings, created by Parsons and Whittley for Ben Adam-Smith’s house:

    Plan – This is an aerial view, looking down onto the building. You can have different plans to show each floor of the building, but they can show the roof, doors, walls and windows, together with the internal layout.

    Elevation – An elevation is a drawing of what the outsides of the building look like from where you’re standing. A south elevation for example would be the side of the building that is facing towards the south.

    Section – This is like slicing down through a building to show what’s inside. It will show the components of the walls, floors, roof etc.

    Details – By taking a section drawing and zooming in you will create a detail. They can be various scales, such as 1:2 or 1:10, and are an in-depth analysis and instruction for the contractor showing how to construct that part of the building. It would show them where the airtightness line is, where the insulation is, and how wide cavities would need to be.

    Soft landings and performance monitoring

    A soft landing is about making sure that once the building has been constructed, that the operator of that building knows how to use it. Obviously if you’ve built it yourself then this wouldn’t be necessary, but if you’ve largely commissioned other people to complete the project then you should have someone tell you how it all works.

    Performance monitoring can take place throughout the build process but in particular Lee refers to monitoring once the building is complete. This uses sensors to check on things like the internal temperature, humidity and CO2 levels, to make sure the building is performing as it was designed to do.

    Tender

    The way you tender will depend on what kind of contract you will have, but essentially a tender is a set of information that is put out to someone for a response. They will price up the aspects on the tender and return it with their figure and requested documentation. It can be a tender for a design team or for a contractor. The returned tender documents are then scored and weighted according to whatever your priorities might be. For some that might be 80% of the marks will be based on how competitive the price is, but for others they might weight it more heavily in favour of quality and not necessarily who is the cheapest.

    A key thing is to make sure the information and drawings you are sending out are as comprehensive as possible. That way it can be priced accurately for what you will be needing. Without that detail they will be adding an element of price risk to their response which will invariably make it much more expensive.

    Window parts

    • Sill – The ledge at the bottom of the frame.
    • Head – The top of a window where it meets the wall. It can be internal or external.
    • Jamb – The side of the window
    • Reveal – The part next to the jamb. Can be internal (usually plasterboard) or external (usually timber or brick). If the reveals are set very deep into the thickness of a wall they can provide some shading to the window
    • Mullions and transoms – Found on traditional Victorian style windows, the mullions are the vertical bar in the middle of the window, and the transoms are the horizontal bar.

    Roof parts

    • Trusses – The pieces, usually made of wood, that actually make the roof structure
    • Joists – A horizontal structural element that supports the floor and/or ceiling
    • Eaves – The part of the roof that overhangs the wall. Usually if it’s a sloping roof it would be the part which overhangs the gutter
    • Soffits – Underneath the eaves, the soffits are the horizontal section that you can see
    • Ridge – The point right at the top of the roof, usually where two pitches come together
    • Verge – The part at the side of the house. Usually there would be a bargeboard or piece of wood that goes down the side
    • Parapet – Usually a piece of wall that protrudes up above a flat roof
    Roof trusses
    Roof joists

    Find out more

    Visit the website of Architype

    Follow Architype on Twitter

    Transcript

    Download a transcript of the interview with Lee Fordham.

    The Hub

    If you’re new to self build and looking for more information, then be sure to check out The Hub. It’s full of great resources, video diaries and support from a community of like-minded self-builders.

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  • HPH276 : A case study of Hope View Passivhaus – with Tracey and Roman Iwanczuk

    HPH276 : A case study of Hope View Passivhaus – with Tracey and Roman Iwanczuk

    Tracey and Roman Iwanczuk explain how they managed to build a Passivhaus on a sloping site in an Area of Outstanding Natural Beauty.

    Interview with Tracey and Roman Iwanczuk

    Having lived in the US for 20 years and at the point where they were preparing to build a house there, Tracey and Roman made the decision to move back to the UK. Being unable to find a house or building plot that ticked all their boxes, they decided to embark on what initially seemed like a fairly improbable chance of getting planning permission to build a property on their six acre field overlooking the Malvern Hills Area of Outstanding Natural Beauty.

    It was a leap of faith

    Initial meetings with a planning consultant and a local architect offered little in the way of optimism for ever getting planning permission on the site. But they persevered and found another architect who offered a more encouraging 50/50 chance.

    Being a greenfield site they used the Paragraph 55 application process for a house of exceptional design and quality that could enhance the area. As Tracey explains, being a greenfield site isn’t always the best use of a piece of land, and their steeply sloping site wasn’t practical for agricultural use.

    “It was a matter of coming up with a way of saying let’s do something that is a benefit for our environment, our area, and maybe even the people who live around here that makes sense.”

    The scheme they came up with was to return three acres of the land to natural woodland by creating an orchard of local species trees.

    They also put in a flood prevention strategy for the neighbours below, who’s properties had experienced flooding from run-off from the field previously.

    The house nestles into the hillside

    The house was designed to have a minimal visual impact and be future-proof for any long term needs.

    The design came about from a series of 15ft² boxes joined together in a single-storey. The principle rooms are south facing and benefit from the floor to ceiling glazing to maximise the beautiful views, with the other rooms being at the rear.

    Despite the glazing, the temperature of the house remains relatively even. The rear wall is built into the hillside so has a lot of surface area that is removed from the equation.

    Being built into the hillside to a large extent determined what build system they could use. In order to get the required structural strength they used concrete, and felt less guilty with the knowledge that the orchard they were creating would be off-setting the carbon.

    A “long, skinny Passivhaus”

    Roman describes the shape of the house as providing its own unique challenges, of which air leakage was probably the biggest. The concrete block walls at the rear get no sunlight, whereas the pre-fabricated concrete plank roof gets a lot of light and a lot of heat. So with different thermal expansion rates between the roof and the walls they used a Passivhaus window tape as a barrier for the airflow and to provide enough flexibility to accommodate any thermal expansion.

    A ground source heat supply provides hot water

    Excavated soil was used to create a level area in front of the house where they could lay pipes for the ground source heat supply. They chose this over an air source system as it is such a peaceful location that they felt it would be less noisy.

    About 80% of the supply is used for hot water, with very little actually being needed for heating. Tracey points out that it does use a lot of energy to run a ground source heat pump and they really notice the difference in their electricity bills in the winter when they’re running it to heat the hot water.

    When it’s sunny they don’t need to use the ground source heat pump as they export excess solar power to an immersion tank for the hot water supply.

    There is a 30 panel solar array

    The array gives almost nine kilowatts of generation capability. There are two first generation Tesla Powerwalls which that feeds, that can store around 14 kilowatts. They don’t have the means of exporting power from the batteries, but what they can do is “time shift” the excess energy generated during a sunny day for it to be used to run the house at night.

    With advancements in technology, the battery system is one thing that Roman is considering changing. When they were installed the only batteries that were readily available were these kind that sit on the DC side of the system. They are almost directly connected to the solar panels, which means that the system is designed to completely switch off the electricity in the event of a power cut. This is because there could be a danger of feeding the power back onto the grid and electrocuting anyone working on it, but it does mean they can’t access any of the energy sitting in those batteries during that period.

    The more modern Tesla system works on the AC side. If there were to be a power cut it would isolate the house but still allow the batteries to generate AC voltage.

    “If there is a power outage, then your house effectively becomes an island of electricity and you can use whatever power is in the batteries.”

    To upgrade to this system will mean a bit of disruption in having to change the location for the batteries, but Roman thinks that it will be worth doing. There is also a second hand market for the Tesla batteries so they can be re-used by someone else.

    The plant room

    They have high praise for their team

    Tracey and Roman consider themselves to have been very lucky in how smoothly the project generally went. The only real issue they had was with the window supply, which has taken around three years to fully resolve, but they do say to the company’s credit they have stuck with it to get a resolution.

    Tracey praises their architect who had never done a Passivhaus before:

    “He was more than happy to park his architect ego, listen to the Passivhaus consultant and do the right thing to achieve a Passivhaus. He was happy to learn all of this stuff and take it on board.”

    They selected a contractor who had also worked with the architect before, and this helped with maintaining good working relationships between them all. Tracey also praises their integrity and says they were very respectful in how they communicated with her.

    Think about your window to wall seals!

    One area that could have challenged the successful outcome of the project, was the seals between the windows and walls. Despite their Passivhaus Consultant, Nick Grant, flagging up how important it was to get right, it had been forgotten about in amongst all the other decisions that had to be made. It wasn’t until a week and a half before people were due to do the render that they realised they hadn’t thought about the window to wall seals at all. It was pure luck that they were put in touch with someone who had some spare pieces from their own self build that they could use.

    “If that had not been done, it would be a nightmare right now. We’d be dealing with silicone, silicone in windows all the time, just doing all of that stuff that would make life miserable. I can’t say enough to anybody who’s looking at doing a self-build; think about that very, very early on because we only fixed it by accident. It was a very, very lucky accident.”

    Roman warns that when you have a window company dealing with the windows, and a builder dealing with the building envelope, things like how those windows will join with the building envelope can become overlooked.

    A HEPA filter would be a worthwhile investment

    The one oversight that Roman feels they made was the issue of airflow in the house. The MVHR draws in outside air but, being in a rural spot, this can include the smell of burning horse manure! The basic filters are there to get rid of particulate matter, but they don’t deal with smells. He recommends the inclusion of a HEPA filter, which he doesn’t think is something he can now retrofit because of lack of space. He considers the £500-£1,000 for a HEPA filter would be money well spent, even more so in an urban environment with emissions from exhausts.

    ASBP Healthy Buildings Conference and Expo 2020

    This is taking place in London on 27th February, and will be addressing the subject of healthy buildings in a climate emergency. Check out the website for the full programme and booking tickets online.

    Find out more

    Visit the website of Warren Benbow Architects

    Follow Nick Grant on Twitter

    Transcript

    Download a transcript of the interview with Roman and Tracey Iwanczuk.

    Please connect with me

    Subscribe, rate and review the podcast in iTunes

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