Contact →

Tag: self build

  • HPH400: Three couples build a terrace of three Passivhaus homes

    HPH400: Three couples build a terrace of three Passivhaus homes

    Bill Butcher and Chris Herring, founders of 21 Degrees, share details of their own group build, a small terrace of three homes in Marsden, West Yorkshire, designed and built to Passivhaus Plus standard.

    Bill and Chris on site

    Interview with Bill Butcher and Chris Herring

    Bill Butcher and Chris Herring, founders of 21 Degrees, have been proponents of the Passivhaus standard since delivering the Denby Dale masonry cavity wall project in 2010. Always open to another challenge to keep them young, Chris has his eyes on being inside his own Passivhaus home before he turns 75 next year. There’s also a community aspect to this because it involves three couples, three homes, one terrace and navigating it all collectively. This is a story about making something happen: pulling on decades of expertise, finding the right people, keeping costs down, and proving that modest, high-performance homes can be built affordably when a skilled group commits to working together.

    Existing stable block on the site

    Taking calculated risks on land can unlock development opportunities

    Chris and Jan purchased a piece of land on the edge of Marsden for a community project, but they also knew there might be development potential for an old stable block on the site. By accepting the risk, they positioned themselves to propose a solution that served both housing and community needs. And even if they didn’t get permission they had a use for the site. In other words they were managing the risk.

    Shared values give strength to the group build

    The Mount Pleasant Self-Build group formed around a common belief in modest, sustainable living. As Chris explains, he and Jan did not want to live in ‘splendid isolation’, seeking instead a community connection. Having worked with Bill for years, he and his wife Jean became obvious potential neighbours.

    “Chris and I have been metaphorically married for the last 35 years!” comments Bill.

    Both Jean and Jan were keen that their partners realise the dream of living in Passivhaus homes after spending so much of their careers trying to drive up standards in construction.

    Jan had also worked with Veronika a lot, knew that she had been looking into eco housing, and so again bringing in Veronika and Ondrej just seemed to be the perfect fit. Another key aspect of this group was their trust for each other and knowing that at certain stages of the project it made sense for certain individuals to lead.

    Emotional resilience is as vital as technical skill in group builds

    Jan noted that when one person feels overwhelmed, there’ll be another positive voice in the group. That way the speed of progress or challenges they face don’t feel so bad.

    Trust in making decisions collectively

    Chris described the Quaker concept of discernment where decisions are reached collectively. You do not always have to decide individually but can listen to others. This collective trust allows for difficult decisions to be made without fracturing the team. Without this support, Jan admitted that she and Chris might not have been so keen to tackle this.

    The planning application was a ‘best guess’ at what would be approved

    The group chose to stay within the existing footprint of the stable block to minimise visual impact. They also nestled the building into the hillside to keep the ridge height down, dropping the floor level by 1.8 metres. The new building would be clad in timber which is the same material that was used for the stable block. This low visual impact was referenced favourably in the planning decision, although it wasn’t the only consideration. Being sensitive to the context may have helped in this scenario.

    Digging into the ground and fitting their designs into an existing form does have an attached cost, but with this consent as a fallback position, there was the option to return to the Local Authority with revised designs closer to what they want. However, the downside is all the extra time it would take, possibly another year, and already two years in they were just keen to move on.

    Mount Pleasant self build plansDownload

    Keep an eye on planning policy changes

    The site occupies semi-degraded land at the edge of the village within the Green Belt. However, it’s defined as a subset called ‘grey land’ which is a relatively new planning policy update. A local landscape architect supported the application on the basis that such land lacks potential. Building housing here protects the edge of the village while meeting housing delivery requirements. It highlights that not all green belt land is equal in terms of planning policy. So understanding the specific definition of ‘grey belt land’ might provide opportunities for development.

    Fabric efficiency + renewables makes sense

    Most of Bill and Chris’ experience with Passivhaus relates to fabric performance, Passivhaus Classic in other words, but they have come around to the Passivhaus Plus category over time. This delivers everything that we’d expect from Passivhaus Classic, drastically reducing energy use, but also incorporates renewables, so that the building meets all its energy needs over the course of the year.

    Chris says decarbonising the grid alone is not enough. The focus remains on reducing energy demand for the lifetime of the building. Renewables act as a complementary layer on top of these efficiency measures.

    What may look like waste can often be reused

    Although the existing timber stable block could not be retrofitted into a new building it had a much brighter outlook than being thrown on a bonfire. Jean listed it on Facebook Marketplace which resulted in immediate interest from a farmer, who came to dismantle, transport and re-erect it elsewhere. The concrete base was also going to be crushed and reused as hardcore for the new parking area. This approach saved disposal costs and reduced the embodied carbon of the project. It serves as a reminder that a little time and curiosity can find value in waste. Demolition should be viewed as a resource recovery phase rather than just removal.

    Site access constraints can sometimes impact how you build

    Chris initially favoured off-site timber frame for speed and risk reduction. However, the roads to the plot are often narrow, with twists and turns, and so bringing articulated lorries through these villages was bordering on the impossible. After going through various options Bill got chatting to Mike Whitfield on a motor-biking holiday in Wales and was persuaded that using their stick-build approach with Masonite I-joists would be perfect here.

    Nick Grant, Passivhaus Consultant and co-author of The Good Building Book

    Early value engineering simplifies design and controls costs

    Nick Grant is the Passivhaus Consultant on this project and throughout his career he’s tried to highlight what early value engineering can bring to a project. With this reputation it made absolute sense for Bill and Chris to lean in. They wanted to make their scheme as affordable as possible and part of that was avoiding complexity. In some ways Bill and Chris even saw this as a learning opportunity because Nick Grant, builder Mike Whitfield, services engineer Alan Clarke and structural engineer Andrew Collinson are the dream team! They have been able to pare things down over the years because they work together often, trust one another and can speak openly if they can see opportunity for improvement.

    Collaborative humility between designers and specialists improves outcomes

    A local architecture firm was engaged on this project. Their skills with space and design would still be required but they were open that they had no Passivhaus experience. Chris saw this as an opportunity for them to learn and develop skills. The key was humility and recognising what the team did not know. Where architects understand Passivhaus, designs are less costly to deliver. However, with so much Passivhaus experience on the rest of the team, in this scenario it was a great move.

    One benefit of a group build is to take advantage of individual skills

    If you’re tackling a build collectively then there’s a good chance you’ve got some useful skills up your sleeve. For example, Jan is a conveyancing lawyer and so in the early stages she was able to drive through the land acquisition, divide up the plots, and negotiate with neighbouring landowners to tidy up boundaries. With the technical design Bill worked on the junction details to minimise heat loss. He’s also well versed with the construction phase and quite at home with co-ordinating the project. The rest of the group understand this skillset and just let them get on with it!

    Bill and Chris as foundation work gets underway

    Leveraging long term relationships reduces overheads and manages risk

    The project pulls on every favour and relationship built over thirty-five years. The Green Building Company team will handle on-site construction with Bill and Chris project leading. Self-managing the build is an obvious choice here. Drawing on in-house expertise for MVHR and triple-glazed windows contributes to cost control. Bill notes that if they cannot do it for a reasonable price, few others can. Currently they are hoping to deliver the project for under £3,000 per square metre. Bill says that from general chat at last year’s AECB Conference a typical figure for a one-off Passivhaus might be more like £3,500 per square metre.

    The foundations are prepared

    Staged financing requires careful cash flow management

    In terms of finance the plan involves mortgaging their existing homes rather than selling up. Chris comments that the cash flow will be tight at certain moments but they know what they have to do. Navigating finance before knowing the full cost is a familiar tension. Timing is everything when staging the drawdown of funds. This approach requires discipline to ensure the project does not stall. It is a reminder that financial planning is as critical as architectural design.

    This is an opportunity for a younger generation to get on the housing ladder

    Bill highlighted that Veronika and Ondrej are getting their first home through this scheme. With massive challenges for first-time buyers this illustrates another way of thinking, that an older generation can bring younger people into these projects. The conventional housing market offers working people almost no realistic path. Demonstrating that Passivhaus Plus is achievable at the upper £2,000s sends a vital message. Modest houses built well at a price that doesn’t require a fortune are possible. This intergenerational transfer of opportunity is key to housing sustainability and sets a precedent for future collaborative developments.

    Find out more

    21 Degrees — Supplier of all key elements for Passivhaus Plus and low energy buildings: MVHR, windows, airtightness products, specialist insulation, air source heat pumps and photovoltaics.

    Green Building Company — The independent construction team carrying forward the building expertise developed over nearly two decades within Green Building Store (now 21 degrees)

    Mike Whitfield Construction — Specialists in stick-build Passivhaus housing who are assisting with the methodology and frame installation for this project

    Hawdon Russell Architects — the architecture lead on this project who are also upskilling in Passivhaus

    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

  • HPH399: The Good Building Book – with Jon Broome and Nick Grant…

    HPH399: The Good Building Book – with Jon Broome and Nick Grant…

    Jon Broome and Nick Grant explain why they have written The Good Building Book, what’s in it, who it will help and how best to put it all into practice.

    Interview with Nick Grant and Jon Broome

    Architect Jon Broome and engineer Nick Grant have years of design and construction experience between them, and have set out to share their knowledge of creating how to make buildings that work. Their book, The Good Building Book, is an attempt to cut through the greenwash and distil practical, hard-won lessons from decades of hands-on experience. Rather than producing an encyclopaedia of building, they chose to write from what they actually know — self-build, community projects, Passivhaus consultancy — and then explore how those insights ripple outward to anyone procuring or inhabiting buildings. The result is a book that asks uncomfortable questions about celebrated projects and invites readers to do the same.

    “It was an idea of trying to distil the sense out of ‘greenery’ and come up with something practical and useful in how people design and build.” — Jon Broome

    Finding examples of ‘great’ buildings is not as easy as you might think

    The title The Good Building Book is deliberately modest. Jon and Nick suggest that it’s easy to improve buildings but difficult to create ‘great’ buildings that are universally loved. You can however deliver buildings that perform well, are cost effective and look beautiful. Sadly a lot of prize-winning architecture fails the people who have to live and work inside it. All too often buildings are treated like sculptures, which quickly eats into the budget.

    Users deserve a seat at the table

    One of the book’s recurring themes is that the people who will actually use a building are routinely excluded from the design process. Jon traces this to a cultural problem in the UK around trust — a reluctance to believe that ordinary people can make sensible decisions about the spaces they inhabit. On the continent, collaboration between professionals and building users is far more common. The book argues that involving users isn’t just democratic; it produces better outcomes, because residents understand their own needs in ways that no brief can fully capture.

    “We must make sure that the users of buildings, the residents and so on, are respected and understood and that they have a role to play in the design and construction and management of buildings.” — Jon Broome

    End users should upskill too

    Nick is particularly keen that the book reaches not just architects and students but the people commissioning buildings. If end users understand a bit more about design process, and what commonly goes wrong, they are in a far stronger position to challenge what they’re being told or sold. The book aims to give people the tools and confidence to question their designers, select the right team, and push back against decisions that don’t serve them. For Nick, this is perhaps the most radical thing the book can do.

    ‘Best practice’ evolves over time

    Both Jon and Nick have built their own homes, and neither pretends they got everything right. Jon’s house, built thirty years ago using massive timber construction, is relatively modestly insulated and very leaky by modern standards — he wishes he’d met Nick sooner to get a better handle on performance. Nick’s straw bale house was inspired by the Segal method, and Pat Borer and Cindy Harris’ book Out of the Woods, but over time he came to see that the material itself is only part of the overall picture and matters less than how you build. Both Nick and Jon are always learning and pour a lot of their first-hand experience into this book.

    Nick’s self build home

    Materials matter less than how you build

    While Jon and Nick have a fondness for timber and bio-based materials, they say that material choice is only one part of it. What matters more is the process — how the building is designed, how it performs, whether it’s affordable and repeatable. Nick points out that a huge building full of bio-based materials that costs a fortune is not inherently sustainable. The book also encourages doing your own thinking and debunking. For example, building a house out of a really sustainable material like cork might seem like a good idea, but there’s actually a limited supply in the world and it would be extremely expensive.

    A good building addresses function, economy and aesthetics

    A central tool in the book is a Venn diagram drawn from the Vitruvian principles of firmitas, utilitas, venustas — but with economy added as an explicit third circle alongside function and aesthetics. Nick explains that too many award-winning buildings hit only the aesthetics circle: they look striking but don’t work well and are wildly expensive. The diagram isn’t prescriptive about what beauty looks like, since that’s subjective, but it insists that all three domains can be addressed.

    Start with function, not form

    One of the book’s strongest arguments is about where you begin the design process. If you start with a fixed idea of what a building should look like — a dramatic cantilever, a disappearing wall — then performance, cost, and buildability become problems you have to solve backwards. If instead you start with the functional layout, the budget, and the constraints, a form emerges that works. You can always add aesthetic flourish at the end, but it’s far harder to retrofit performance into a shape chosen for its visual impact alone. Vernacular architecture is a result of the process rather than a style — and that process starts with what the building needs to do.

    Old Holloway, Juraj Mikurcik’s straw panel Passivhaus

    Sufficiency trumps efficiency

    When asked whether sufficiency matters more than efficiency Nick is clear: you can never do enough efficiency to compensate for simply having more and more of everything. He contrasts a vast Passivhaus mansion covered in solar panels with a modest, small building like Juraj Mikurcik’s self build home. The larger building may be highly efficient per square metre, but in absolute terms its environmental impact is far greater. Claiming that a huge, efficient building is environmentally friendly is, in Nick’s view, a problem. Sufficiency — building only what you need — is the foundation that efficiency builds on.

    Slate House is an affordable Passivhaus

    Genuine value engineering delivers better buildings

    Nick draws a sharp distinction between real value engineering and what usually passes for it. True value engineering happens when a collaborative team — architect, structural engineer, fire engineer, quantity surveyor, M&E consultant — sits down together and solves problems creatively, often knocking significant cost off a building while improving its performance and buildability. Cost cutting, by contrast, is what happens when a project runs over budget and the nice stuff gets stripped out: wooden windows replaced with plastic, natural flooring swapped for PVC. The first approach bakes good decisions in from the start; the second is a desperate salvage job at the end.

    Passivhaus is a tool that can deliver desirable outcomes

    The book discusses Passivhaus openly, acknowledging that simply mentioning the word can alienate half an architecture audience. But Jon and Nick treat it as a practical tool to deliver outcomes we want. For detached new-build homes, they see it as close to a no-brainer — you get comfort, low energy bills, and a building that’s easy to live in. For small bungalows, the heating target can be a stretch, requiring very thick walls, and they suggest a slight relaxation of the target might make scaling up easier without meaningful penalty. For flats, the challenges shift to ventilation and hot water distribution rather than heat loss. The key point is that Passivhaus gives you tools for certain problems; for example it doesn’t tell you how to lay out a house or choose materials.

    Beware innovation for innovation’s sake

    Jon and Nick warn against the word “innovation” appearing in a brief. Genuine innovation emerges organically when you’re solving problems — and that’s welcome. But when innovation becomes a requirement, whether driven by planning policy or a BREEAM credit, it can disrupt the whole process. Walter Segal, Jon notes, believed that designers have a duty not to use their clients’ money for their own satisfaction and ego. The book encourages readers to focus on principles — comfort, affordability, low impact — rather than chasing the latest certification or buzzword.

    RUSS is a members-led Community Land Trust

    A Community Land Trust is a way to keep housing affordable in perpetuity

    Jon’s involvement with the RUSS community build in Lewisham illustrates what becomes possible when people are trusted to organise themselves. The project began with workshops to establish shared principles, then evolved through a two-weekly cycle of group design discussions involving around fifty people selected by ballot. Some residents, such as Kareem Dayes, took on shell units and fitted them out themselves.

    What’s special about a Community Land Trust is that it takes land out of the open market, so that it remains affordability going forwards. Jon sees ‘diversity of offer’ as essential to any comprehensive housing policy, because the market simply doesn’t supply what a lot of people want or need.

    The space between buildings has an important role to play

    One aspect that Jon mentions a couple of times is how we mustn’t overlook the space between buildings: it’s how we understand places, and it’s where community life happens. Too much focus on buildings as objects, rather than as part of an active process involving the people who use them, leads to places that may look good in photographs but don’t work as neighbourhoods.

    Find out more

    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

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

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

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

    Interview with Kirsty Maguire

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

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

    Accessing a number of plot opportunities is part of the process

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

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

    Get to know what your plot priorities are

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

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

    A site with a lot of constraints can become a positive

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

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

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

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

    A lot of the core decisions fell into place

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

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

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

    Thinking about privacy is also part of the window design

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

    Talk to your neighbours to get their support

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

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

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

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

    Some features of the house were not optimal for achieving Passivhaus

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

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

    The size of the windows matters

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

    Skylights can be tricky to shade

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

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

    Finding time to work on the project was challenging

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

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

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

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

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

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

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

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

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

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

    If you have a dream explore it with an architect

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

    Passivhaus delivers a healthy and comfortable internal space

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

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

    Find out more

    Kirsty Maguire Architect

    How to incorporate reused materials on a self build

    Progressing your house build plans before you have your land

    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

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

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

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

    Interview with Sally Godber

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

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

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

    Managing risk became an integral part of taking on a project

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

    Scaling down a project scales down costs

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

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

    Risks can often be identified

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

    Reducing the number of ‘unknowns’ reduces the overall risk

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

    Complexity increases risk

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

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

    Know your absolute price when buying at auction

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

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

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

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

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

    Achieving planning permission was an emotional roller coaster

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

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

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

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

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

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

    A simple design reduces the risks during construction

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

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

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

    There were challenges using a standard timber frame

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

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

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

    Remedial work enabled them to achieve the airtightness target

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

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

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

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

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

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

    It’s worth taking the time to get things right

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

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

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

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

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

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

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

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

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

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

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

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

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

    Sally’s husband is now an advocate of Passivhaus!

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

    Try to enjoy the whole house-building journey

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

    Find out more

    WARM

    Coaction

    Passivhaus Homes

    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

  • HPH383: A beginner’s guide to creating a comfortable home – with Andy Mitchell

    HPH383: A beginner’s guide to creating a comfortable home – with Andy Mitchell

    Andy Mitchell, Managing Director of 21 Degrees, explains what factors influence human comfort and how we have tried to make our homes more comfortable through the years. Embracing building physics has been a turning point and while we have the knowledge and skills to create healthy and comfortable homes today, it’s still not the default approach. So Andy outlines the options available to get yourself into a better home.

    Interview with Andy Mitchell

    Andy Mitchell is the Managing Director of 21 Degrees. Engineering runs in the blood as he comes from a family of engineers and he has always been fascinated by houses and buildings, even considering architecture as a possible career path at one stage. Studying product design at A-Level he then became interested in company structure and business. His first significant role in sustainability was at a company called Natural Building Technologies in the early 2000s, where there was a focus on healthy bio-based materials. Today he heads up 21 Degrees, a company which supplies key technology to homeowners and architects enabling them to build more efficiently, and generate and store energy.

    In this podcast Andy explores the concept of comfort and explains why we can do much better when it comes to creating a comfortable and healthy home in which to thrive.

    We can define a comfortable temperature

    While we might think that we are all different and therefore prefer to live at different temperatures, that is not true. We can define a comfortable temperature range because of our physiology.

    “Any human being, no matter where they are on the planet is most comfortable between 20°C to 22°C. The reason is simple. If the temperature is higher, your body has to work harder to keep you cool; and if it’s colder, your body has to work harder to keep warm.”

    The body doesn’t cope well under 15°C

    Below 15°C humans have to work hard to keep warm. At 9°C or less, it’s a matter of survival.

    How active we are, alters what we perceive as a comfortable temperature

    If we’re engaging in a lot of activity, such as cleaning our homes, we are generating heat and keeping ourselves warm, so may desire a cooler temperature. Alternatively, if we are working at a desk and sedentary then the reverse is true and we may want it to be warmer. Generally speaking the impact of this is plus or minus 2°C.

    Putting on clothes is another dynamic

    You only need to look to the Inuit in parts of Greenland to understand what an impact clothing can have. They could survive in subzero temperatures. The downside is that their clothing was bulky and would limit the activities they could perform. Any clothing will go some way to making us feel warmer because it’s trapping the body’s heat and slowing it down from moving away from the body. It would be the same effect sleeping under a duvet. The duvet is insulating your body heat.

    Relative humidity levels impact our health and comfort

    Humidity, or the level of moisture that’s in the air relative to the temperature, has an impact on comfort. The warmer the air, the more moisture the air can hold. And generally, humans are most comfortable at 50%, plus or minus 5%. It’s quite hard to fix humidity levels but between 40-60% is seen as a healthy range. If the levels exceed 70% regularly then these conditions can lead to damp and mould, which are damaging to human health. Below 40% is not good either and could cause respiratory issues.

    Lowering the temperature to save money will create an unhealthy environment

    Andy explains that it may be a false economy to turn down the thermostat in winter to save money or reduce fossil fuel usage. This is because as you drop the temperature the relative humidity goes up.

    “If you had a temperature of 22°C and the relative humidity was 50%, and you dial the temperature down to 18°C, you’ll actually increase the relative humidity to 64%… You’ve made yourself slightly more uncomfortable because you’ve increased the relative humidity.”

    With poor ventilation, which is common in many British homes, the relative humidity may have been closer to 55% anyway.

    “If we’re closer to 55% relative humidity that really starts to get interesting, because if you dial down from 22°C to 18°C, you’re at 73% relative humidity and that starts affecting your health. For example, dust mites proliferate above 70%, eczema and asthma are a direct consequence of allergic reactions to dust mite poop. You’ve also got issues with mould growth.”

    Radiant heat also plays its part in comfort

    In addition to temperature and humidity, radiant heat plays a significant role in how comfortable we feel. Andy shares a couple of examples of when you might have experienced this.

    If you’re taking a stroll on a sunny day and a cloud goes in front of the sun, you might notice you suddenly feel a bit cold. The air temperature hasn’t changed. What’s happened is the radiant heat that’s been hitting your body has dropped because it’s been obscured by the cloud.

    Radiant heat is also absorbed and emitted by surfaces in our homes such as furnishings, walls, windows, etc. So the temperature of those surfaces will have a significant impact on your comfort levels.

    Our homes have got better over time!

    Over the centuries we have turned to fires to keep us warm. In Victorian times there were open fires, which were extremely inefficient because most of the heat went straight up the chimney. However, the rooms felt more comfortable because of the radiant heat being absorbed and then given off from walls and furnishings, etc.

    “The big, winged armchairs that we perhaps thought were to stop granddad falling out of his chair when he fell asleep were actually to keep the radiant heat in… It captured that heat that was being radiated out from the fireplace in the room.”

    With the advent of cheap energy, such as access to North Sea gas in the UK, we could pipe fuel straight into our houses. Burning this in boilers, heating water and then piping it around radiators was a big leap forwards. Although fossil fuels are energy dense and have been an easy source of fuel, their emissions have contributed to global warming and we have nearly exhausted the supply in a few decades. 

    Indoor temperatures have been increasing

    Back in the 1970s, the average temperature in a British house in winter was 12°C – 13°C. These days, it’s probably closer to 18°C – 19°C. Andy says that figure could be impacted by a number of people who are in genuine fuel poverty. In other words, they find it unaffordable to heat their homes. One reason for this is that the UK has a large amount of old and leaky properties.

    Leaky homes are just about tolerable in a mild climate

    Andy says that the UK has the most inefficient housing stock in Europe. While Germany is on a latitude further South and might face temperatures of -10°C, a British winter is milder and more akin with Italy. Therefore with a few token measures, such as double glazing, and cheap energy, we have got by.

    “Sadly, I think we focus more on basic survival and then toleration, rather than what makes for a great home? What really does give us that extra level above survival, so that we can thrive? Again, to me, this is very much what comfort brings… It means you can be more productive in terms of your work. You’ve got higher levels of energy, because you’re not using it to keep yourself warm or cooler.”

    Sensing a ‘muggy’ environment indicates pollutants have built up

    As we live in our homes the indoor air is changing. We exhale CO2 and generate moisture from our activities. Relative humidity builds up and there may even be VOCs given off from furniture, paints, etc. Our instinct is to open a window, which Andy says will solve the problem.

    “By opening the window, you purge the air to the outside, because generally warm air will move to the outside, particularly if there’s a bit of cross ventilation, and as a result, arguably, the temperature will be dropping a bit. But if you don’t leave that window open for too long you’ll have a complete air change, and the air that’s come into that room, because the walls and the fabric are warm, to some extent, that air will warm up. And what was outside air, which was probably around about 70% relative humidity, would have dropped down to around about 50% relative humidity, and suddenly you feel much better again!”

    The problem is this purge is needed regularly and is hard to manage. More often than not there will be a drop in internal temperature.

    In winter another source of discomfort is draughts, where you’re sensing changes in air temperature. For example, if you stand near windows that are single or double glazed, they are colder than the internal air temperature so you will feel the heat moving away from your body.

    You may also experience stratification of the air and this heat differential causes air movement, which in turn can make you feel uncomfortable. For example, your feet can feel colder than your torso. You may not even be aware of it.

    We have got to grips with the physics of buildings and know how to build better homes

    In the past we have simply put our buildings together without worrying too much about how effective they are, focusing more on aesthetics. However, there is an approach that works and has been around for over thirty years. Dr Wolfgang Feist and the team at the Passive House Institute decided to look at things from the first principles and get a holistic picture. This led to the development of the Passivhaus standard, which is a formula that anyone can follow to make a building that works. Core principles include insulation, airtightness, high performance components such as windows and doors, reducing or eliminating thermal bridges, introducing mechanical ventilation with heat recovery, and orientating the building towards the sun.

    Andy points out some of the benefits. For example, in a Passivhaus the temperature of the surfaces will be plus or minus 3°C of the air temperature. It will be draught-free and the heat loss will have been reduced significantly. The introduction of mechanical ventilation with heat recovery also means there’s constant fresh air coming into the building, but the heat from the outgoing stale air is retained. And this is a way of controlling the relative humidity, too.

    So building or buying a certified Passivhaus is one way of ensuring you have a comfortable and healthy home.

    Buying a new home doesn’t necessarily mean it’ll be efficient or healthy

    Although the Passivhaus standard was developed decades ago, the learnings and methodology have not been incorporated into the building regulations. Therefore there is still a performance gap in most new buildings, where the design intent is never reached in the completed building.

    We are all responsible for the status quo

    Not only do we as homeowners tend to accept the status quo rather than demanding higher standards, but architects, designers and contractors struggle to adopt new strategies. So sometimes the drawings fail to give enough detail, particularly around things like airtightness or thermal bridging, which is just where you’ve got surfaces or materials joining together, and you can get additional heat loss that you wouldn’t do through the principal wall or roof or floor areas. It can be the contractors on site, who don’t fully understand the goals of the project and might cut through a membrane not realising the impact of doing this.

    Then there’s the building standards themselves. The reality is the building standards stop at the point of design. Currently there is no ‘as-built’ check of the performance.

    “So the performance standard stops at the design stage because you demonstrate through something called SAP, Standard Assessment Procedure, what is the heat loss from this building based on the building fabric. It’s pushed through a calculation. Effectively, it says yes this fabric will pass, and that’s where the testing ends. There is nobody from Building Control actually measuring the heat loss of the building once it’s occupied.”

    The choices are getting better

    Andy believes that building to a performance standard above and beyond building regulations is becoming more common. We’ve mentioned the Passivhaus standard but there’s also the retrofit standard EnerPHit. The AECB New Build standard is another option, which is slightly easier to reach, but has the same rigorous building physics approach.

    Building your own home allows you to get what you want

    When people are building or commissioning their own homes they almost always strive for higher standards. And doing a self-build project is not quite as onerous as it might seem, with more and more help available. Andy says we build about 5% of our homes in the UK this way, or 15,000 homes a year, which is equivalent to the output of the fourth largest volume house-builder in the UK. This is a good start but to put it into perspective Germany deliver around 50% of their homes as self-build. So maybe it’s not surprising that these standards have taken time to be adopted.

    It is possible to improve the performance of an existing property

    If building new or buying from the open market is not proving successful, then there is another option. Existing homes can be retrofitted to a performance standard. It is often harder, and some homes will be more challenging than others. For example, how the building is orientated is something that is hard to change. There are also significant costs for a deep retrofit.

    “The more complex a building is in its form, often the more challenging it is to reduce the heating requirement, the heat load. You can still go a long way, though, to improve airtightness and therefore comfort levels but you might not achieve the same low energy results that other more simpler forms of building can.”

    On a phased retrofit, improve the ventilation first

    Doing a retrofit in one hit often makes life easier, but not everybody is in a position to do this. So another option is to do a phased retrofit. The most important part is to have a comprehensive whole house plan at the beginning.

    Andy says that a good first step is to improve the ventilation of a property because that will give you cleaner, fresher air, with more controlled levels of relative humidity. While it may cost a bit more in heating initially until you have reduced your heat loss, you can immediately benefit and also reduce the risk of damp and mould building up in places where you have improved the fabric but have not improved the ventilation yet.

    The average family home produces up to as much as 15 litres of moisture a day that goes into the air. This evaporates from our bodies when we’re sleeping or walking around the house. Moisture is also generated when we’re cooking, taking a shower or doing the washing, and it has to go somewhere.

    So after the ventilation has been addressed, the next phase might be looking at improving the airtightness and replacing the windows.

    Adding insulation changes the physics of the building

    When you apply products to your building, you are changing the physics of the building. So if you apply a piece of insulation to a part of your property, you are changing what was there before, and if it hasn’t been well thought through you could end up with unintended consequences. Andy gives an example of fitting closed cell insulation internally which is principally a bad idea because you are likely to trap moisture in the wall. This interstitial condensation could ultimately lead to the building fabric being damaged or breaking down, or potentially creating mould pockets, which then can affect the quality of the air in the room.

    Mechanical ventilation must be designed well

    There are various ducted ventilation systems on the market but they have to be designed well to be effective.

    “The ducting design, for example, in MVHR is far more important than the actual unit that you plug into the end of it. A decent fan and heat exchanger is important, but you can have the best MVHR unit on the market and you plug it into poor ducting design, and you’ll just have a poor system. Whereas you could have an average MVHR unit and plug it into some effectively designed ducting, and you’d have actually a very good system.”

    MVHR can be useful if the outdoor air is not clean

    If the external air quality is poor, such as on a busy road, or if there’s a lot of pollen that is having a particularly bad effect on a hayfever sufferer then a fully vented, ducted system often takes the air through filters. So you can filter particulates from outside and stop them coming into the house.

    Making a home more healthy and comfortable shouldn’t be about payback

    When people go on holiday they don’t look for the payback on their holiday! People are also prepared to spend a lot of money on a kitchen. However, when you tackle a big project that will improve health and save money on bills, they suddenly believe it should pay for itself.

    Treat homes as homes, not as assets

    It would be good if we moved away from viewing houses as assets, and actually looked at them as a way to help us live effectively.

    Andy is tackling his own retrofit

    We are all on a journey to creating better homes for ourselves and our families. And that includes Andy! He is making improvements to his Victorian home with a phased approach.

    “You do a measure to your own property, and you still find yourself being quite impressed! So we live in a Victorian property, and half of the floor of the property is a cellar. The other half is solid floor, and we insulated in the joists of effectively the cellar part, and that made a significant improvement. And then the following year, we had an airtightness membrane installed underneath the joist and the insulation, and that made as significant, if not more significant an improvement in both the thermal performance of that room.”

    Andy believes that most of us become complacent with our homes when we actually have the opportunity to enhance our lives.

    “As human beings, we have this incredible gift of adaptation. The problem is it’s also a curse, and we just tolerate an awful lot of rubbish. If our awareness was increased and we could begin to learn what is possible, particularly in terms of how we can live within our built environment I think the change for our welfare, both as individuals and society in general, would be significantly impactful.”

    Find out more

    21 Degrees

    Why MVHR maintenance and servicing is important

    What makes a well designed MVHR system?

    How do you specify high performance windows?

    Two radical retrofits that use an internal wall insulation strategy

    Low energy barn conversions

    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

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

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

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

    Interview with Ben Nother

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

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

    The role of Principal Designer has evolved

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

    CDM Principal Designer and Building Regulations Principal Designer

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

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

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

    The Principal Designer now takes on more responsibility and liability

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

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

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

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

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

    The Principal Designer role continues in the build phase

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

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

    The client must understand who the Principal Designer is

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

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

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

    There are multiple considerations for the materials and products being used

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

    Manufacturers generally have all the information you need for products

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

    The regulations should be front of mind from the outset

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

    The welfare of your build team is important

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

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

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

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

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

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

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

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

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

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

    Find out more

    Hawkland Group

    Hawkland Architects

    Hawkland Construction

    Transcript

    Download a transcript of this episode.

    Subscribe to our YouTube channel

    Have you subscribed to our YouTube channel? Well, it’s a good way to get notified about new videos that we make. For example, Colin and Janice Gardiner tell the story of Hazel Tree House in a recent addition to the channel. Find out what they have learned from taking on a new build project. We’ve got a video (or you can read their blog post). And here’s the link to subscribe to our YouTube channel. Enjoy!

    Please connect with us

    Subscribe, rate and review us on Apple Podcasts

    Follow Ben Adam-Smith on LinkedIn

    Follow Ben Adam-Smith on Bluesky

  • 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

  • Ten things we learnt about building a house

    Ten things we learnt about building a house

    Janice Gardiner reflects on her eco build and shares ten of the most significant lessons from the project.

    1. Spend time thinking about how you want to live in your house

    We knew from the start that we wanted to build an eco house so contacted architectural practices that specialised in eco builds and soon found Green Trace Architects. Our architect, Joshua Wood, then took us through a process to determine our values, how we wanted to live in the house, how we wanted the spaces to interact with each other and what we wanted it to feel like, before any designs were put on paper. For us sustainable materials, along with a social space for family and friends to gather was important. We also wanted to feel that the house was connected to the land around it. This informed Josh’s designs which included a large open plan living area, a wood panelled ceiling, clay plaster walls and large windows that connect us to the outside. The end result has lived up to our vision.

    2. Visit other self-builds of a similar style

    Whilst researching different building systems Josh came across EcoCocon and discovered the architect Juraj Mikurcik had built with this system just up the road from our site. Juraj kindly showed us round his house, Old Holloway, which was the first time we experienced what might be possible. It’s all very well talking about and seeing images of Passivhauses, but it’s only when you experience one that it really sinks in. There was a calmness and a feeling of peace that had quite an emotional effect on Colin and that was the moment when we could imagine how fantastic our build could be. Juraj was also able to pass on lots of useful advice and ideas, which we incorporated into our designs. This included getting rid of the wood burning stove and underfloor heating as in his words they operate as very expensive pair of slippers. The reality is that we only need minimal additional heating in the coldest months.

    We didn’t go for the EcoCocon straw system, because we were building in the winter and didn’t want to risk the straw panels getting wet. In the end, we had a very dry winter and EcoCocon may have been an easier material to apply the clay plaster to, but that is just how things go.

    3. Understand the planning process

    We bought the land with outline planning permission, but no design for the new dwelling, which left us free to submit our own designs. Permission had been granted based on replacing an old wooden building, with the condition that the new house could not be more than 100m2 internal floor area. This is relatively small, but by including the double height ceiling over the dining area, Josh was able to increase the house footprint and make the house feel more spacious. Upstairs the roof line slopes to the floor in places, and anywhere where the height is 1.5m or less is not included in the floorspace calculation. Again, this added to the house volume and these areas became useful storage with built in cupboards. These design features have made the house feel bigger without adding to the internal floor area, showing that you can be creative within the planning restrictions.

    Whilst we never wanted a large house, in hindsight we could have made an argument to make the building slightly bigger. Areas like the second bedroom and the plant room would have benefitted from a few extra square metres and the site itself could also take a larger property.

    4. Do your own research even if you have a project manager

    As novice builders we were not sure what we didn’t know and maybe relied too heavily on the professionals around us, who didn’t always realise what we didn’t understand. At times it may feel like you’re speaking different languages! For example, with the cost of the round window we just thought about the actual window, not how it would fit to the external tin and how to produce a curved frame. So even though everyone was saying this will be expensive, we didn’t really get the whole picture. Doing research into the different stages of the build and becoming familiar with the different processes would have helped us to ask better questions and make more informed decisions.  

    5. Know your own strengths and weaknesses

    Personality traits are important, as they will influence your decisions, so really think about what you are good at and when you may need extra help. We knew what we wanted, had dreams of a Passivhaus, had watched Grand Designs avidly for years, but never thought we would be in the position to do it. So, when faced with a simple design or a more architecturally interesting one, we were instantly tempted by the latter, which inevitably led to us spending more money!  Our original design also didn’t include solar panels or aim to be Passivhaus certified, although we did ideally want to do both. So, when we found out our builder was also a solar panel engineer, and the designs were actually achieving Passivhaus standards we went for both. Consequently, we really stretched our finances but have achieved a better outcome. In general, we are better at interior design than sticking to budgets!

    6. Work with people with similar values and trust them

    The desire for an eco-build influenced our choices from the start and what we hadn’t realised is that Herefordshire is a hot spot for Passivhaus builders. Serendipity brought us Dai Rees, The Passive House Builder, who lived just 8 miles away. Dai and his team were brilliant to work with, had wide ranging skills, including carpentry and tiling, and put so much thought into making the house as beautiful as possible. One example is the internal wooden ceiling. Juraj from Old Holloway shared a photograph of his ceiling, where with 3 widths of timber he created a pattern that appeared random. Dai and his team painstakingly replicated this and then added new edging to create a slightly different feel.

    Inevitably there is problem solving needed during the build and it probably would have been useful to have had Dai on board before Josh’s designs were complete. This would have allowed them to work through some of the technical aspects together, like how the roof met the main beam, before starting the build. The downstairs shower room was another conundrum, with the design only getting finalised late on in the build.

    7. Your builder will follow your architect’s plans

    That may sound obvious, but we did forget that the plans contained things we weren’t totally sure about. For example, Josh was aware that we were doubtful about the external low wall around the front of the patio, but Dai was not party to those discussions, so footings for the wall were in place before we realised. In the end we didn’t build the wall, so work had been done unnecessarily.

    8. Effective and timely communications are important

    We found we were quite redundant in the early stages of the build; Dai was following Josh’s plans and we weren’t really needed. But when it came to the fitting out, we suddenly found we had numerous decisions to make. The first thing was:

     “Where would you like all the electrics? The electrician starts next week!”

    These weren’t on the plans, so a few late nights were spent working out socket positions, lighting and light switches. We had been a little naïve about this aspect and maybe too laid-back. We then had to look at light fittings, toilets, bath, showers, tiles, kitchen design and fittings, staircase, interior doors, handles – everything that goes inside a house needed to be chosen and sourced. Sometimes these decisions are needed to be made before the structures/walls were even in place, so it was hard to visualise the end result. How do you choose the colour of bathroom tiles when you have no walls or green OSB board as your backdrop? Never mind that every space looks so small before the walls are in place!

    Good fun when you get your head around it and you will never have to make this many decisions so quickly ever again in your life… unless you build another house.

    9. Look at different financial models

    We went for a cost-plus approach, where we had a broad indication of the cost of the build at the start, but were open to any fluctuations in material costs during the build. In effect we held the risk for price increases but potentially could also make savings along the way. Timber prices increased during this period of time, but we also chose a more cost-effective roofing/cladding material. We trusted our builder to get us good prices, and it gave us lots of flexibility during the build, but it was harder for us to keep on top of costs. We would also agree to things without asking for the full costs, often not factoring in the labour costs of a particular item, such as a custom-made sink unit for the main bathroom.

    Basically, we were dealing with a changing budget rather than having things agreed up front through a fixed price build. In some ways this flexibility suited us and resulted in better finishes, but it did mean we spent more overall.

    10. Don’t aim for perfection

    Things will inevitably go wrong, hopefully minor and easily put right, but problem solving is part of building a house. Sometimes potential problems will be spotted early on and so can be avoided. For us, it was Dai realising we needed to make one of the walls in the plant room removable in case the boiler broke down. We were very glad he did this as the boiler was faulty on installation, so had to be taken out and replaced straightaway. Other times you will make decisions you end up having to live with. For us, not putting a hand basin in the downstairs shower room was one of them. Water pipes and wastewater points are put in with the foundations and at that point we hadn’t decided on the layout of the shower room. As it was small, and we didn’t know how the shower doors would open and we decided to do without a handbasin. The room was next to the utility, which has a sink and most of the time this is okay, but it’s not ideal for people staying over. We can now see there actually would have been plenty of space for a hand basin.

    Working with a good team certainly made the build an enjoyable process for us. It didn’t necessarily stop us worrying about the decisions we were making, but that’s part of building a house. We now have a beautiful calm home that sits lightly on the land and will look after us for many years to come. We still have lots of external landscaping and gardening to do, but luckily we like doing that!

  • HPH375: A day in the life of a builder – with Mike Whitfield

    HPH375: A day in the life of a builder – with Mike Whitfield

    Mike Whitfield shares his experience of running a local construction company that specialises in Passivhaus. He explains how the business is structured, and what tasks are tackled on a daily and weekly basis.

    Interview with Mike Whitfield

    Mike Whitfield, the owner of Mike Whitfield Construction, began his career in his early twenties, working in America, Canada, and Australia. He had always wanted to be a carpenter and learnt about timber frame building whilst working abroad. Returning to the UK in the 1990s he got involved in oak frame construction for a while before rekindling his interest in energy-efficient buildings. The AECB was a great source of information to keep at the vanguard of green building, and so Mike was well placed to take on Passivhaus building when it came on the scene. 

    Mike has been a guest on the podcast before when he helped us identify the traits of a good builder.

    There is a demand for Passivhaus builders

    Once Mike Whitfield began to focus on building high performance homes it naturally led to more of this type of work. So from 2010 onwards nearly all his projects were to Passivhaus or EnerPHit. As these projects require a greater attention to detail and high quality workmanship, over time Mike Whitfield Construction has built up a reputation of being able to deliver.

    In fact, as they are seen as the go-to Passivhaus builders in Herefordshire, Mike even believes they may have missed out on jobs!

    “If you get a reputation for being too busy, you can miss out on jobs. People say I didn’t bother asking you, because you’re always busy.”

    A core team of people is key to his way of working

    Mike explains that he has a core team of people employed by his company. This is different to the typical British builder model, which uses self-employed subcontractors on ‘zero hours’ contracts.

    Being part of a regular team makes it possible to develop skills and knowledge, which is essential to a Passivhaus project.

    One of the advantages of being a well-established company is that Mike has built up a network of additional collaborators, from architects and groundworkers to electricians and consultants. It all helps the operation run smoothly.

    A local builder can often end up wearing many hats

    Mike is now 67 and trying to step back and hand over the reins to others.

    This has been an interesting process because he’s been able to contrast where the business is today, as it moves to become employee owned, versus how he started as a sole trader.

    In the early days, as is common with many small builders, the paperwork gets done in evenings or over weekends (which means working long hours each week).

    As a more established company of 11 people today, Mike has been clear that there needs to be more than one person stepping up so the load can be shared in a more sustainable way.

    There’s now a slightly different structure in place. For example they’ve got two site foremen, with one taking on more responsibility for liaising with the clients, and the other one able to concentrate on the construction. An office manager is also in place to handle the paperwork and order materials.

    Maintaining momentum requires good communication and organisation

    Mike’s work has changed recently now the foremen are taking on more responsibility. However, even with the new structure the same key tasks need to be completed.

    There’s a briefing on site at the beginning of the day so that each team member knows what needs to be achieved and can get to it. There’ll be various aspects for the foreman to oversee, such as the quality of work, the progress, and receiving deliveries.

    There’ll be meetings with the client or consultants, always looking ahead to the next steps.

    And in the office there’ll be various ordering and invoicing.

    “It’s just a question of keeping the materials flowing to it, making sure our office manager knows what’s going on and our office management system is working well. In my previous life I was on site at 7.30am to get people going, then in and out of the site hut organising things. I’d be lucky to do an hour or two of the practical work before leaving at 3.30 to go back to do a couple of hours work in the office.”

    Mike prefers a ‘collaborative procurement’ process

    Drumming up new business can be a process that takes years. It might start with a phone call from a potential client, who is looking for a plot of land. Mike would normally refer them to the architect he works with most frequently. It might go quiet for a couple of years, and then finally the discussions about the design begin.

    Costing a new scheme draws on data from previous projects

    Mike has detailed records for the outputs and costs for each stage of a build, so he can input prices at the design stage. He calls it a collaborative procurement, rather than doing a tender or some other method. A lot of architects in the Passivhaus world now accept that it can be good to find a builder you like and trust, and just work up the price with them.

    “Working from a basic sketch we can have a good go at pricing the build using our previous experience and our pricing programme. If we know the client’s budget, we can work with that and assess what is possible for the money. Mutual trust is important.”

    The team must always be working on a project

    One of the trickier elements of being a builder is keeping a steady flow of work for the whole team.

    Mike describes the ideal scenario being where their groundworkers have started the next project, whilst his team is on the main project, and maybe one or two people are second-fixing the last project.

    Of course life doesn’t unfold perfectly and sometimes they have to do things differently.

    Mike shares an example from last year when he had two jobs running in parallel. Luckily, they were only a few miles apart from each other, which helped.  

    A builder will often have a site on standby for quieter times

    When there are gaps in the schedule Mike can move the team onto one of his own projects. He says last year they had three jobs, totalling £1.5 million, in the pipeline but couldn’t start any of them. So having a plot as a fallback option means they can divert resources to do part or all of the build. Again, in a perfect situation the team would be completing the whole project in one go, but they could just do the groundworks and pause, or they could get the shell watertight and then bring things to a halt.

    Building to Passivhaus standard demands more from a business

    In Mike’s experience, Passivhaus building requires more attention to detail and greater supervision, and the profit margins are tighter.

    Although there is a lot of job satisfaction in delivering high quality buildings there is no doubt it is much harder than simply complying with building regulations. For a conventional build it is relatively easy to find a good site supervisor, use a quantity surveyor for pricing or give drawings to a builder’s merchant for them to work out the quantities you need. Mike has always had to do his own pricing and recognises it is harder.

    Want to see how a timber frame project comes together? Check out our Buckinghamshire Passivhaus case study in The Hub

    Track record is the best way to gauge a builder can deliver a Passivhaus

    Mike thinks that clients who commit to building to Passivhaus standard have thought a lot about what they want, and therefore the service needs to reflect this. In the early days people would realise part way through construction that they’d taken on the wrong builder and they weren’t going to get a Passivhaus at the end.

    It’s slightly easier now because a builder should be able to show you a portfolio of certified Passivhaus projects. If they’ve only completed one or perhaps just do ‘Passivhaus principles’ then this may be the point to ask a few more questions.

    Pricing up retrofit projects is challenging

    Although there is demand for retrofit projects Mike says they are certainly trickier. They’ve tackled 4 or 5 so far, and it took until the fourth one for them to make any money. There is an argument for doing them on a ‘cost plus’ basis as you don’t know what you’re going to find before you start.

    However Mike generally prefers to work on a fixed cost basis, with everything agreed at the start and then its up to him to bring it in for that price. It can mean tight margins if prices spiral after you’ve quoted, but on the whole it works well.

    It’s easier for builders to upskill today

    As Mike gradually steps back from the business he reflects on his career in a positive light.

    Some aspects of running a building company are tough, especially on your own, but he has always loved the craft of the work.

    To others who want to follow in his footsteps and build to Passivhaus standard, Mike says that the good news is that there is a lot more information and training available compared to when he started out. It will demand more from you and your team, but if you’re up for a challenge and committed to this way of working it can be extremely satisfying.

    “It is hard to find the right people, but if you can, and you’re all working together, it is so much easier.”

    His advice to young people starting a construction company now is to find men and women who share the same goals as you, so you can form a team to share the workload and support each other.

    Find out more

    Mike Whitfield Construction

    Transcript

    Download a transcript of this episode.

    Please connect with us

    Subscribe, rate and review us on Apple Podcasts

    Follow Ben Adam-Smith on Bluesky