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Author: Lucy Cowell

  • HPH319 : Natural materials and healthy homes – with Tom Woolley

    HPH319 : Natural materials and healthy homes – with Tom Woolley

    Architect, educator and builder, Tom Woolley, takes us through some of the natural construction materials we should be using to build healthier homes.

    Interview with Tom Woolley

    Tom is a returning guest to the podcast, with hempcrete being the subject of his previous interview.

    Now, he has a new book: Natural Building Techniques – A Guide to Ecological Methods and Materials, and it is topics within that which we have been discussing with him. His book includes sections about renovating and retrofitting, information about suppliers, and different kinds of natural materials that are available. It also looks at some recent case studies, talks about how to tackle projects, and what some of the obstacles might be that you could come up against.

    The supply chain of natural materials is becoming far more robust

    Tom explains that for a long time people have been given excuses about why natural materials are too expensive or don’t work, which has acted as a barrier to their take-up.

    However, in recent years, a lot of work has been done to make the supply chains more robust, with greater availability and, in some cases, cheaper pricing. This in turn has encouraged more people to try them.

    Tom also believes that new fire and thermal performance regulations will make it harder for plastic and synthetic insulation companies to fabricate results, and composite materials like hempcrete will be shown to be just as good.

    The term that is generally used for natural materials is bio-based materials, which covers anything from timber and straw, to hemp, sheep’s wool, and other natural fibres. Closely linked are also things like earth and lime.

    We need to stop using timber carelessly

    When it comes to the sustainability of using natural products, Tom addresses the current problems with timber.

    “There’s enormous amount of wastage of timber really. Timber is used in many situations, where it probably isn’t needed to the extent that it is, but people just chuck it in as though it’s a cheap material, which it no longer is.”

    He also says that there is a lot of misinformation around the flammability of cross-laminated or mass timber construction, which has resulted in people returning to use concrete.

    We do though need to be careful and responsible in our use of timber, and Tom explains that there are companies in the UK that are constructing using locally harvested roundwood poles, which is a great way of using timber more responsibly and economically.

    Tom also suggests that there are many more resources that remain untapped, for example the biomass waste from palm oil trees could be used for bio-based composite products.

    Lime and clay can be great alternatives to cement

    Tom has been working with lime for a number of years and says that it is a natural biocide which is very good for healthy buildings. It does however still use energy to produce it, so he is now experimenting with a clay powder that seems to work almost the same as the lime, and which would save a great amount of embodied energy.

    Stone and earth are two of the oldest forms of building material

    Stone is a natural material that can be re-used and Tom is horrified when he sees sites being bulldozed and the stone being buried, when there are far greater benefits with the many other ways it could be used.

    While cob and rammed earth have plenty of advocates, using these materials alone it can be hard to reach modern standards of energy efficiency. However, they are hygroscopic and have health-giving properties that make them a very good material to use.

    Tom is a great believer in hybrid construction these days, and building with timber, sheep wool, earth, hemp and all sorts of other things, depending on what’s available and how they can be combined together.

    Straw can be tricky if you don’t know what you’re doing!

    Tom admits that he’s not the biggest fan of using straw as a construction material, largely because he’s seen so many straw bale disasters!

    People often think because straw bales are relatively inexpensive, then it must be cheap to build a straw bale house and anyone can do it. However, there are a number of pitfalls, such as when you have a roof resting on the walls you need to factor in that bales are going to move, their suitability in very wet conditions, and having to be extremely well rendered and plastered to make them safe from fire.

    He has however seen some wonderful examples, particularly when the straw bales are used as infill within a timber frame, rather than being load-bearing.

    If you are looking to build with straw, Tom recommends getting experience first on another project so that you know what’s involved, and preferably attend a training course run by experts.

    Hempcrete is an excellent material for managing moisture in a building

    This would always be Tom’s preferred method of building, used as 300-350mm walls within a timber frame construction. It has an impressive thermal performance and also creates a very healthy environment because of its hygroscopic properties.

    Over the last year, they have had a study done by the University of Ulster on one of their hempcrete buildings. Despite temperature and humidity levels varying greatly throughout that time, the relative humidity stayed exactly the same.

    It is also very versatile in its application. It can be mixed in a mixer and cast in shuttering, it can be sprayed into a building, and it can also come in block form.

    Hemp is readily available for use in construction, with more growers jumping on the bandwagon of bio-based materials for company carbon off-setting. It is a useful crop for farmers because it’s used in the annual rotational cycle between cereal crops such as barley and wheat. The fibre is stripped from the hemp and this in itself becomes extremely valuable. The hemp fibre can be used in a variety of insulation products or composites, including car interiors and replacing plastic in aeroplanes.

    Emphasising eco-credentials can make mortgaging more challenging

    Tom thinks that sometimes approaching insurers, mortgage providers, planners, and building control professing your wacky eco house ideas can be detrimental!

    He suggests that by being more tactical and not making a song or dance about it, you’re less likely to have a problem. He gives the example of a small company in Wales who have just sold a trial hempcrete house, which got a mortgage from Nationwide Building Society without them batting an eyelid.

    “It’s no good just saying, Let’s insulate it”

    With his book, Tom is keen to educate even some of the green movement who emphasise the importance of insulating all the buildings in Britain, while effectively promoting the use of petrochemical insulation materials.

    “There must be lots of white van men out there just happy to come and stick any sort of plastic rubbish into buildings. That is not good enough. We have to get people to use the right materials and the right techniques that aren’t going to damage the planet and aren’t going to damage people’s health.”

    He accepts that there will always be some things that can’t really be made out of anything other than plastic, and if they’re used in a sparing and limited way then that’s something that shouldn’t be condemned. However, he takes issue with some of the Passivhaus organisations for promoting materials that are plastic and synthetic oil based, which they are claiming will help to save the planet by reducing energy. When 50% of the plastic waste going into the oceans is from the construction industry, Tom questions why they need to be wrapping buildings in plastic membranes, when we can build airtight buildings with hempcrete that are fully breathable and aren’t wrapped in plastic.

    Active House provides an alternative to Passivhaus

    Tom sees Active House as having a more holistic and sensible approach to these issues, particularly around the design and configuration of buildings, use of daylight, passive solar etc. The Active House Alliance has recently been set up in the UK and certification will be offered in the future.

    We don’t have enough building performance data

    Tom is keen to see far greater investment in building/material performance data, but says that while organisations such as Innovate UK have thrown money at petrochemical solutions, they haven’t been as supportive of natural and bio-based approaches.

    There are however some very good centres of research that are being set up, such as at the University of Suffolk. Tom has also been in discussion with Cardiff University about doing some testing on further hempcrete houses that are being built in Wales.

    “We know that they work, but it’s no good having the anecdotal information that we know that they work really well, and even better than synthetic materials. We need to have the hard facts, we need to have the data. And we also need to have more standards.”

    Research in the UK and around the world shows that issues around mould are another big challenge that needs to be faced, even for properties that have been renovated. But there are now many in the medical community that are recognising the environmental causes of health problems, such as VOCs, formaldehyde etc. Tom sees natural materials as being the solution to get out of these problems, and this is likely to be one of the main directions of his work in the coming years.

    Find out more

    Visit the website of Rachel Bevan Architects

    Find out more about Natural Building Techniques: A Guide to Ecological Methods and Materials

    Transcript

    Download a transcript of the interview with Tom Woolley

    Please connect with us

    Subscribe, rate and review us on Apple Podcasts

    Like our Facebook page

    Follow Ben Adam-Smith on Bluesky

  • HPH318 : Do I need a structural warranty for my self build home? – with Jake Fitness

    HPH318 : Do I need a structural warranty for my self build home? – with Jake Fitness

    Jake Fitness of Self Build Zone explains what a structural warranty is, and why you might need one on your self build or renovation project.

    Interview with Jake Fitness

    Jake Fitness is a team leader at Self Build Zone, a provider of site insurance and structural warranties.

    A structural warranty is a type of insurance policy

    It can cover any new structural works you do on a project, whether it be a new build, renovation or extension.

    It will be more costly to add on at the end

    Jake stresses that the ideal time to start thinking about the structural warranty is when you have a pretty good idea of what your project will entail. This is for three reasons:

    • To ensure that your building is acceptable to warranty providers
    • To be able to factor it into your project budget
    • Leaving it until the end will mean they charge a higher price, as the surveyor won’t have had full visibility of the build process.

    “If you’re thinking about doing a project anytime soon, really make it one of the first things you do, because it’s more important than your kitchen, your doors and your windows and all of the nice looking fittings, because ultimately, it’s what’s going to pay you if there is something wrong with your build.”

    Typically the price of a warranty is based on the size of the property, the frame construction type, and the build cost. The average warranty cost is between £2,500 and £4,000. This covers the full premium for the 10 years, plus all the site audit visits.

    It isn’t a legal requirement

    It is however likely to be a lender requirement if you’re looking to re-mortgage the property within that first 10 years, or if you are going to sell it during that time. You can still purchase a warranty at that time, but you will end up paying a far higher price for it.

    It doesn’t hold anyone liable for the damage

    The difference between a warranty and a standard contractor’s guarantee, is that you don’t have to hold anyone liable for the damage that has been caused. This is because rather than blame being placed on the architect or contractor for cracks etc, the warranty provider will conduct an independent survey to assess the damage and pay you for that loss. This can be beneficial if you’re looking to sustain the working relationship with the team in the future as you’re not trying to place blame on an individual or company that may not even be at fault.

    Technical audit surveys are carried out

    These repeat visits are similar to that carried out by a building control officer, but are purely from the viewpoint of whether there is likely to be a claim within the next 10 years. They are more comprehensive than whether they just meet building regulations, and on a new build would typically take place:

    • when the foundations are fully excavated but before the concrete is poured
    • at the damp proof course stage
    • for brick and block it will be when you’re at first floor joists, or for timber frame and ICF it will be when the frame has been erected

    “We’ll still carry on even when you’re at the weathertight level all the way up till completion, letting us know of any defects during the build, which, to be honest, most builders if they’ve built a small defect in then they’re probably going to not let you know about it. But we will stop the building in its tracks if we need to, just to make sure everything’s rectified and built to a very good standard.”

    A structural warranty will cover defective design, workmanship and materials

    This will be for a period of 10 years after completion.

    An example of this could be the structural engineer not designing the foundations deep enough and the property subsides. Worst case scenario would be a claim for completing demolishing and rebuilding.

    Other things that would be picked up could be things like a roof not being designed to take the full weight of solar panels, or poor mortar mixture being used that needs remedying.

    Select a provider that has an A rating

    Although the actual cover of the warranty is much the same for all providers, it is important to check that who is actually insuring and paying for the claims has an A rated backing. This relates to how financially stable they are, and how likely they are to still be around in 10 years time if you do need to make a claim.

    Jake says an unrated insurer should be avoided as they don’t have evidence of their stability within the market.

    He also recommends doing your due diligence by checking out blogs, reviews and testimonials to select your provider.

    All construction types can be covered

    Jake explains that Self Build Zone will cover all construction types, because each self build is so different. Rather than making blanket statements about the construction types they are able to rely on the auditing process from when they come out to do the inspections. This includes straw bale with thatched roof, and green oak frames.

    Having been a warranty provider for over 20 years, Jake says that they are helped by being in the position of knowing what causes claims within the 10 year period, and the types of risks associated with each construction type.

    A structural warranty is more comprehensive than alternatives

    Contractors have a defects period where they will be responsible for all claims for the first two years following completion. That’s not something that you would typically have under a self build warranty though, as self build can relate to anything from full involvement by the contractor, right up to 100% of the work being done by the homeowner themself. If you do rely on a contractor’s guarantee and they go out of business within the following 10 years, you won’t have anyone to go back to for any of the defects that may arise.

    Likewise, architect’s certificates (Professional Consultancy Certificates) are also sometimes available, but will only cover defective design, and not the workmanship or materials for the property. You would also have to prove that the architect was at fault, and are usually only valid for six years. In contrast, with the structural warranty, you don’t have to evidence the fault to any particular party to claim, and it would be provided for 10 years.

    Another reason for having a structural warranty, is that sometimes local authorities may ask for one to show that your property is a self build and therefore exempt from paying a community infrastructure levy.

    Find out more

    Visit the website of Self Build Zone

    Follow Self Build Zone on Twitter

    Transcript

    Download a transcript of the interview with Jake Fitness

    Please connect with us

    Subscribe, rate and review us on Apple Podcasts

    Rate and review the podcast on Stitcher

    Like our Facebook page

    Follow us on Twitter

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

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

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

    Kit Knowles (Rick McCullagh)

    Interview with Kit Knowles

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

    The SuperHomes network and trade shows provided information and inspiration

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

    The Thorns (Colin Poole)

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

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

    The Thorns (Colin Poole)

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

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

    The Thorns (Colin Poole)

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

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

    Clients can dilute the environmental ambitions

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

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

    Aesthetics matter

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

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

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

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

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

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

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

    Kit uses a three level approach:

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

    Lymm Hall is giving him the chance to trial new approaches

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

    Lymm Hall (Lymm Photographic Society)

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

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

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

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

    Lymm Hall (Lymm Photographic Society)

    Achieving Passivhaus Premium on multiple dwellings will be a world first

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

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

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

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

    Find out more

    Visit the website of Ecospheric

    Follow Ecospheric on Twitter

    Transcript

    Download a transcript of the interview with Kit Knowles

    Please connect with us

    Subscribe, rate and review us on Apple Podcasts

    Rate and review the podcast on Stitcher

    Like our Facebook page

    Follow us on Twitter

  • HPH316 : Why we must embrace sufficiency – with Lloyd Alter

    HPH316 : Why we must embrace sufficiency – with Lloyd Alter

    Lloyd Alter explains how we can take personal actions to address our own carbon footprints, and why it’s more important to do so than ever.

    Interview with Lloyd Alter

    Lloyd Alter is an eminent writer at TreeHugger, a teacher of sustainable design at Ryerson University, and has spent many years working in the built environment field. But for his latest book,”Living the 1.5 Degree Lifestyle”, he has taken a wider view on the behavioural changes we can all make to lessen our carbon footprints and impact on the planet.

    Personal actions matter

    Lloyd took umbrage at a headline in the Guardian newspaper in 2017, that said 100 companies are responsible for 70% of emissions. By seemingly laying the blame with the oil companies it took away personal responsibility, and this was something he fundamentally disagreed with. As individuals, we have choices and are responsible for consuming what the oil companies are selling. It’s the consumption, not the production that is the biggest issue.

    According to a study by Aalto University in Finland, The 1.5 Degree Lifestyle, 72% of emissions come from the choices we make, such as driving and eating habits, and it is these decisions that drive consumption.

    The target average carbon footprint is 2.5 tonnes by 2030

    Around the same time that Lloyd was reading into the idea of the 1.5 degree lifestyle, the activist and London mayoral candidate, Rosalind Readhead, was trying to live a lifestyle with the carbon footprint that we’re going to have in 2050, of one tonne of carbon per year. While he felt that would be impossible to manage, he did think he might be able to achieve the 2030 target and had agreement with a publisher to write a book about it.

    “So that basically started the project of what can I do to produce less than 2.5 tonnes of carbon emissions for an entire year.”

    An example of how Lloyd was tracking his carbon footprint

    It is far easier to achieve in certain locations

    By virtue of living in Toronto, Lloyd was already at an advantage over other locations when it came to the impact of his electricity usage. What with its nuclear and hydroelectric power generation, rather than coal-fired plants, the power there is almost entirely carbon-free.

    He also lives in a suburb where he can collect groceries on foot, so not driving for a year becomes easier.

    This is all in stark contrast to more remote areas just 100 miles away that have to rely on coal power, and vehicles for getting provisions.

    Our street design should encourage walking, cycling and using public transport

    Without sufficiency, efficiency is lost

    One of the key things Lloyd has learnt through this process is moderation. How much is enough? By looking at life through a lens of sufficiency, you can ask yourself the questions such as do I need to build as big, or buy as much, or drive to the shops when perhaps walking would be better?

    A big surprise for him was how, after gas usage, his Apple devices were the biggest contributor to his carbon footprint. Although they’re designed to use very little electricity, when embodied carbon is taken into account an iPhone alone releases 80kg of carbon in its manufacture.

    Lloyd has always loved his Apple gadgets

    “When you look at everything through the lens of embodied carbon, it changes everything.”

    Lloyd now questions for example, whether there is a need to keep upgrading mobile phones when invited, when they are still perfectly efficient. And whether a new electric pickup truck seems such a good idea when its 40 tonnes of upfront carbon emissions is equivalent to nearly a lifetime allowance under the 2.5 tonnes that he is allocating per year!

    With regards to housing, you could build a house that’s really big and efficient, but because it’s big it’s using more energy than a smaller house would. And although polyurethane foam has the best R value, it has a huge upfront carbon cost, especially when compared to cellulose or straw. This is why it’s important to build sufficiently, with the right materials that have the low embodied carbon, and that are relatively local.

    Low rise, multi-family Passivhaus apartments in Munich

    People’s perceptions have been changed by the energy crisis

    Lloyd explains that two years ago when he spoke about Passivhaus, he had to talk about comfort and health, because energy was so cheap that putting in more insulation didn’t pay. However, with spiralling energy costs people are far more worried about building for resilience and ensuring that the house needs to use as little fuel as possible.

    “If you’ve got a given budget, and you build better with more insulation and higher quality windows…you’re going to have to probably build a little bit smaller.”

    Living sufficiently isn’t worse, just different!

    An automatic reaction to thinking about this lifestyle approach, is that it will be less enjoyable, but Lloyd explains that this doesn’t have to be the case. Whereas he used to enjoy snowboarding, the reality was that he had to drive for three hours in order to get electrically winched up a hill, and slide down artificial snow made with electricity and water pumped up from the lake. He now straps a pair of cross country skis to his ebike and heads for the nearest park.

    He is also now eating a lot less red meat and trading it instead for more white meat or vegetarian options. He’s not missing the steaks as now his diet is actually more varied and interesting.

    He doesn’t feel he’s trading things for a more marginal experience, he’s just trading them for a different one.

    The one area he does feel that he will struggle with though, is air travel. The US and Canada don’t have such good rail links as the UK and Europe, but the cheap airfares in Europe also make hopping on a plane for a weekend trip very attractive to many people. He thinks this will be the hardest thing for people to adjust to.

    Lloyd has always enjoyed travelling to Portugal for their Passivhaus conference

    “And we’re just going to have to change the way we do it, you know, no wild little weekend trips. But maybe you pack them together, take two weeks, go somewhere and really enjoy it and amortise that flight over a whole year worth of carbon.”

    It’s far easier to make the changes if you realise what your carbon footprint is

    Lloyd has had many comments from people who have read his book saying that it’s changing the way they live, because these were things they just hadn’t thought about before.

    For Lloyd himself, one of the greatest joys has been replacing many of his car journeys with using his ebike, and he believes these could have the biggest impact in suburban areas. Other people are sharing his views and he talks of people telling him they’ve replaced their second cars with ebikes instead.

    He also says that you don’t have to be rigid about your self-enforcement. If the single biggest thing you can do is cut back on eating red meat, then great, but that doesn’t mean you can’t have the occasional steak.

    Personal actions also set an example to other people. Using the parallel of how smoking has become gradually more socially unacceptable over time, he hopes the same will become true of our carbon footprints.

    Privilege can be a blind spot

    Lloyd understands that he is in a position of privilege to have been able to make the changes he has without it being too much of a disruption to his life, but he appreciates that’s not possible for everyone.

    “That’s the hardest thing that we all have to look at. It’s not to think, well, the example that I’m setting is something that works for everyone. We have to change society to the degree that the structure is there, so that people do have choices that they don’t have to choose between food and heat in their houses. We have to make it more equitable and more fair.”

    Find out more

    Visit the website of TreeHugger

    Follow Lloyd Alter on Twitter

    Purchase a copy of Living the 1.5 Degree Lifestyle

    Transcript

    Download a transcript of the interview with Lloyd Alter

    Please connect with us

    Subscribe, rate and review us on Apple Podcasts

    Rate and review the podcast on Stitcher

    Like our Facebook page

    Follow us on Twitter

  • HPH315 : Simplifying the delivery of high performance, sustainable homes – with Mike Jacob

    HPH315 : Simplifying the delivery of high performance, sustainable homes – with Mike Jacob

    Mike Jacob explains how Kiss House is using timber component based production to deliver homes to the Passivhaus standard.

    Interview with Mike Jacob

    Mike Jacob’s journey from project manager of quirky conversions and renovations to co-founder and director of Kiss House happened organically, and stemmed from his ongoing desire to do things in a better way. He continued developing his education and qualifications, learning more about sustainable architecture at the Centre for Alternative Technology, and working for a Passivhaus startup.

    Kiss House “brought itself into being”

    After a decade spent delivering one-off, complex housing projects, Mike and his colleagues felt that there must be an easier way of transferring their lessons learned into a vehicle that could benefit more people, rather than starting from scratch each time. In doing so, they saw the benefit of scaling up a business that had a repeatable housing product, which felt like it had been individually designed, but without the risk, uncertainty, and stress that often goes along with that.

    A bespoke house that a colleague had designed for a private client, started to get enquiries because people thought it was a configurable, repeatable house. This kickstarted their thinking that this could be their vehicle for transferring their lessons learned, and began exclusively working on Kiss House.

    It was important for their designs to have an identity

    The Kiss House design is a contemporary, cuboid, minimal piece of architecture, drawing on their previous experiences and inspired by landmark projects from the 20th century, to offer more of a mass customisation approach to housing. Although the company is still in its relative infancy, as they develop new housing types they intend to stay within a kind of aesthetic language, being contemporary in nature.

    The custom build style alleviates many of the risks

    In Mike’s experience, many of the truly bespoke projects tend to come unstuck and have tensions for a number of reasons. Often this will happen when trying to incorporate high levels of energy efficiency, and can either end up with compromises on the architecture or the performance.

    The Kiss approach aims to be a simple, stripped back, clean lines aesthetic, with uncompromising performance. It can be configurable to an extent, but is ideally suited to a custom build market. Moving forward, they will be building a portfolio of individual Kiss houses that all have commonalities, and beyond that they’re having conversations with local authorities and developers who are interested in different typologies, all recognisably Kiss, for delivery of housing at scale.

    Each house will be built to the Passivhaus standard

    Together with developing their system, they have developed the architectural language for that system which enables them to have a much more flexible kit of parts approach to housing typologies that are more site specific. They are also working hard to ensure that each house will be Passivhaus certified.

    They will have their own manufacturing facility in the UK

    Mike explains that by vertically integrating themselves with their manufacturing partners, they’ll be able to de-risk the supply chain wherever they can. They’ll be bringing as much in-house to their manufacturing facility as possible, including the manufacture of the triple glazed windows, to become a one-stop shop for their housing product. And by being more in control of their supply chain, they’re able to offer a better service to their customers.

    “We’ve tried to come up with something that addresses all of the pain points, or as many of the pain points as we believe are there, so that our customers maybe even enjoy the experience!”

    The ambition is to use only UK grown timber

    Currently, the only imported material they use is sheet timber, which they use sparingly and are trying to find workarounds for. They are trying to galvanise the domestic supply chain and are looking at ash and beech for things beyond the structure, such as for furniture and flooring.

    Working with the Bio Composite Centre at Bangor University for the last couple of years, Kiss House are also looking to bring to market a UK manufactured natural fibre insulation.

    The house is partially pre-fabricated off-site

    The kit of parts is manufactured at their facility in the south of England, and is made up of two different types of columns, along with cassettes and panels of various shapes and sizes. They are manufactured digitally on a semi-automated basis and to high levels of precision. The components that leave the facility are insulated, and sometimes with internal lining boards and external cladding. These are then transported to site, where they are assembled without the need for a crane or scaffolding. A typical house would take just a few days on site before it’s airtight/weathertight, and then a further 4-6 weeks for the fit-out stage.

    The first house will be a demo

    Mike explains that they’re currently manufacturing their first house, which will be a demo house built at the factory. Their first live projects will be delivered on site as soon as they can get them through the planning system, where they’ve been experiencing horrendous delays.

    It has taken plenty of perseverance to keep going against the odds!

    Having lost around two years because of things like lockdown and planning delays, it has been a challenging journey to get to where they are today. However, they, and their patient investors, have kept faith and are at an exciting growth stage where they are joining forces with their manufacturing partner to embark on a new round of fundraising.

    Find out more

    Check out our previous podcast with Mike Jacob: Does Hiring a Project Manager Save Money?

    Visit the website of Kiss House

    Transcript

    Download a transcript of the interview with Mike Jacob

    Please connect with us

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  • HPH314 : Getting a self build over the finish line, despite setbacks – with Mike Coe

    HPH314 : Getting a self build over the finish line, despite setbacks – with Mike Coe

    Mike Coe gives a final update on his now complete Portree Passivhaus, that has seen budgets stretched, contractors disappear for a year, and a Covid lockdown!

    Interview with Mike Coe

    Mike Coe is a returning guest to the podcast. We have been fortunate enough to speak with him about his previous self build, Cropthorne Autonomous House, and have been following his progress since moving to the Isle of Skye to build Portree Passivhaus with his partner Lizzie. Having been in the house for a year now, we pick up where we left off three years ago, in episode 259 when the house was almost watertight, and find out whether Mike has managed to be as hands-off with this project as he had intended!

    Mike had always intended to do the MVHR installation and electrics himself

    He had started on the MVHR installation as soon as there was enough building there for him to work on. The main ducts that bring the fresh air in and take the exhaust air out, went in almost at the foundation stage, as they were assembled as the wall was being built that the ducts pass through. This way it meant they could be built into the wall, rather than having to cut out a large hole afterwards. He also started channeling out for power points before the concrete blocks were even up to first floor level.

    The specification of the MVHR was important for Mike as he wanted to build this house with no heating system whatsoever. They selected a system made by Nilan, which also contains a micro heat pump. It’s only around 60 or 70 watts, but it effectively aids the heat extraction process and makes it more efficient. It means that in the winter the heat pump comes on when the temperatures dictate it, making the incoming air temperature slightly warmer, and in the summer it provides a very small amount of cooling.

    Their only other source of heating is from a single bar electric fire which they’ve used infrequently, just for the odd hour here and there.

    It maintains a comfortable temperature

    The internal temperature on the night they moved in was just 11 degrees (with a raging storm and a power cut for good measure!) But once Mike got the MVHR up and running a couple of days later, and they had a week or two of sunshine, and with the effect of the two of them living there, it took just a couple of weeks for the temperature to rise to 21 degrees. Since then, they have been pleasantly surprised at how well it keeps a steady and comfortable temperature, even more so than the Cropthorne house, despite its larger form and having been less fastidious in the attention to Passivhaus detail. Mike suspects this is because of using the concrete blocks which, as well as providing the structure of the building, also act as a thermal store. He is conscious that the use of the concrete blocks and steel means it has higher CO2 emissions from the manufacture than that of a lightweight timber structure, but this was primarily dictated by the planning department.

    Mike’s previous Passivhaus experience paid off

    With a contractor and architect that didn’t have experience of building a Passivhaus, Mike found one of his roles on site being that of quality control. When it came to airtightness tape, he was able to show them how the standard builder’s merchant tapes would just tear like paper, yet the Passivhaus airtightness tape was incredibly strong and flexible.

    They didn’t mind and were happy for Mike to take on other pieces of work, such as some of the carpentry, especially as he and Lizzie were on site doing the MVHR and electrics anyway, and it meant the workload for their men was reduced.

    It took twice as long to build as planned

    The original plan was for a 15 month contract build period, but at the 10 month stage the contractor got called away to work on a 25 bedroom hotel extension, leaving just Mike, Lizzie and a freelance bricklayer to carry on with the work. This meant an incredibly frustrating almost year-long wait while the hotel project was finished, which unfortunately then coincided with the first Covid lockdown.

    “So there we were, with another three months added on to the almost year long delay due to the hotel build. The hotel extension was sitting there virtually complete, but they couldn’t open it because of everything was shut down because of Covid, whereas our house was nowhere near complete and nobody could work on it except me.”

    Mike managed to use that time as productively as possible to keep the project moving forward. Without being able to access new building materials as the merchants were closed, he dismantled some of the temporary stairwells that the contractor had put in so he could use the timber for building the stud partition walls. He used all the plasterboard that was laying around that he could, rescued timber that had been thrown out and used that for the stud walls, and also managed to build a new desk. Psychologically he found all this beneficial as it felt like progress was still being made.

    In total, the project took around 30 months to complete.

    Money became very tight

    With the planning department selecting the most expensive option, they always knew that the budget was going to be tight. In addition to the overruns caused by the lockdown, a number of other bills came in that caused them to go over by £34,000. This included £8,000 to install a water pipe from the mains halfway up the hill, rather than being able to connect from the supply of the neighbouring bungalow that they owned and were living in, and £750 for a tree survey to make sure that the pipe wasn’t going to damage any tree roots!

    As they were running out of money and with cash being tied up in the neighbouring bungalow until it was sold, they had to take on more of the work than they had ever intended to do. Mike had been unimpressed with the plumber who had done the first fix, so ended up rectifying some of his work and also did the second fix plumbing. This meant he plumbed the washing machine, kitchen sink, dishwasher, and the fit-out of all the bathrooms.

    With great reluctance, as it is a job he and Lizzie particularly dislike, they also ended up doing most of the decorating themselves.

    One year on, there are problems to rectify

    Having been in the house for a year, they are currently in the snagging period where the contractor will rectify some of the problems that crop up. Their contract allowed them to withhold a small percentage of the total payment, which will be paid once these have all been sorted. However, there are other problems which Mike intends to take on himself.

    The door in the lower ground floor porch was never properly adjusted and would stick and not shut fully. When he got round to looking at why this was, Mike discovered that it was actually causing a serious damp problem. The damp had resulted in the hinges corroding, with the adjustment screws for the doors then being impossible to turn.

    Something else that Mike will need to tackle, is an issue with the windows leaking. As they weren’t a standard specification that the contractor was familiar with, they installed them but weren’t confident to set them up, instead leaving this to Mike to organise. However, with all the other jobs and distractions going on, this got pushed lower down the list. With the driving rains they receive, several of the windows subsequently leak. Thankfully there are no serious structural leaks though, and when all the adjustments to doors and windows have been carried out then hopefully that should be an end to those problems.

    During a period of extremely high winds recently, part of the zinc capping that goes around the roof parapet was torn off. Fortunately it doesn’t threaten the structure of the house in any way and it’s still watertight, but it’s something else to add to the list of jobs.

    He has some carbon-saving projects lined up

    Now that they have freed up their cash by selling the neighbouring bungalow, and once Mike gets over a certain amount of self-builder fatigue, he is keen to make headway on some other projects.

    The first is installing a PV array that will make the house run more efficiently, as it will contribute to hot water and charging their new electric vehicle.

    He is also in the early planning stages of putting a micro hydro generator (a little water turbine) into a stream that runs down through their site. If it works it will likely only generate around 100-150 watts per day, but that will be for 24 hours a day and virtually through the whole of the year.

    He is adamant this will be his last self build!

    Now he and Lizzie are able to reflect on their journey, they are able to say that although lots of things went wrong, they managed to get them corrected. Although they did have the benefit of experience from their previous self build, there were still new problems that this project threw up that had to be dealt with. Overall, Mike says they are pretty happy with the end result, just not necessarily with how they got there.

    Find out more

    Visit the website of Portee Passivhaus

    Follow Portree Passivhaus on Twitter

    Follow Mike Coe on Twitter

    Catch up on previous episodes with Mike Coe

    HPH259 : Constructing the masonry superstructure of Portree Passivhaus

    HPH220 : How to finish a self build when money is tight

    HPH152 : Should you consider the resale potential of your self build

    HPH054 : Building an autonomous house

    Transcript

    Download a transcript of the interview with Mike Coe

    How relevant is mass?

    Es Tressider is a guest on the Building Sustainability Podcast, talking about whether adding mass to a building will make it more energy efficient.

    Please connect with us

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  • HPH313 : What input might an engineer have for a Passivhaus self build? – with Gwilym Still

    HPH313 : What input might an engineer have for a Passivhaus self build? – with Gwilym Still

    Gwilym Still, of Max Fordham engineers, explains how good planning and simplicity can improve a home’s performance.

    Interview with Gwilym Still

    Gwilym Still is Passivhaus Leader and Director at Max Fordham engineers. Sadly Max passed away earlier this year, but Gwilym explains the lasting impact that he has left on the culture of the practice that he founded. They are focused on recruiting staff who are passionate about design, and then teach them about building physics, rather than recruiting people who have been formally trained in building physics or engineering.

    Max Fordham celebrating his house winning the RIBA London Sustainability Award 2019
    Max Fordham House (photo copyright Tim Crocker)

    There are many conversations to be had at the outset

    It is rare for a self-builder to bring in an engineer on day one of their project, but if they did they would be having valuable conversations around things like: the architectural shape, massing and form factor, orientation, glazing and shading, construction types and, whether it will be easy to make airtight and well insulated.

    Having these discussions early on means that they’re not going to get emotionally attached to a particular design, only to discover much later on that it may not be practical to achieve.

    The kitchen at Max Fordham House (photo copyright Tim Crocker)
    Max Fordham House (photo copyright Tim Crocker)

    Design choices have trade-offs

    Gwilym explains that part of his job is about helping people understand the impact of the choices that they make, and the trade-offs that are involved. An example is, as a rule of thumb, that the form factor multiplied by 100 is roughly the insulation thickness that will be needed to get to Passivhaus levels of heating demand. By understanding that, clients then decide what their priorities are, and whether adding in an extra room or feature is going to be worth the extra spend on insulation everywhere.

    Focus on good daylighting instead of over-glazing

    People often fall in love with glossy magazine images of heavily glazed houses, without entirely considering the downsides and summer comfort risks.

    Gwilym suggests aiming to set window sizes so that they will give you really good daylighting within rooms. Where possible, orientate the rooms so that living rooms are on the south elevation, and bedrooms on the north. Also aim to have the window head height higher rather than lower, as this will help with getting daylight further into the room.

    Start with sizing windows for daylight and ventilation, and then check things like solar gain and summer comfort risks after that. You can also consider the G value of the glazing at this point, so how much heat it lets through compared to the solar energy that’s coming onto the window, and how much visible light it lets through too.

    Ventilation should be an early consideration

    While this can often be overlooked and left to work out later, it’s actually a good idea to consider the ventilation system as one of the very first things you think about. Things such as: making sure there’s space for the ventilation system to go, that it’s close to an external wall, that there’s sensible ductwork routes, and that people know which rooms they will be supplying fresh air into, and which ones they’re going to extract from.

    Incorporating these early will achieve the best efficiency from the system, making it easier to commission and operate.

    Make early decisions about the energy strategy

    This should be to decide how to heat the space up, and how domestic hot water will be provided. For a lot of schemes, this will now be electric based as people look to decarbonise the grid. Particularly for Passivhauses, the calculations they’ve done show the additional cost of a ground source heat pump doesn’t really make sense over the performance that people are getting out of air source heat pumps now.

    Air source heat pumps do have their own challenges in Passivhaus houses, particularly as there aren’t many low output units. Where the space heating demand is so low, the problem isn’t getting enough heat into the building, it’s making sure that the heat pump doesn’t switch on and off really quickly or really often.

    As general principles then, if you’d like a hot water cylinder, that should be fairly close to the things you’d like it to deliver hot water to, such as showers and sinks. And ideally, that’s fairly close to the heat pump unit, which is outside. As they have a particular aesthetic, which not everyone is keen on, you can then factor in the consideration about whether you need to integrate it into a design that conceals it as much as possible. The acoustics should also be considered, as although they’re generally fairly quiet, it’s still worth positioning them possibly nearer to the kitchen or living areas which will be less noise-sensitive than a bedroom.

    Thought should also be given to the size of the plant room, to ensure there won’t just be enough room for the MVHR unit, but also space around it for changing filters or accessing it for repairs.

    Designing bathrooms and en-suites so that they are fairly close to the hot water cylinder means that pipework runs can be minimised, and the hot water will reach them more quickly. Also give thought to the sanitaryware that will be specified, and opt for low-flow options. As Gwilym says, there’s no point in having an efficient heat pump to deliver your hot water, that then gets squandered by a jungle deluge showerhead draining it off really quickly!

    Early drainage considerations can minimise heat loss

    There are elements of drainage systems that you wouldn’t normally think of in a construction project that can have an impact on the heat loss from the building, and the heating demand.

    With Passivhaus projects, it’s quite common to have soil and vent pipes terminated inside the building with an Air Admittance Valve, so it’s worth making sure that it’s in a place where it can be accessed and maintained in the future.

    And then where Building Regulations want the drainage vented to outside, doing that outside the building envelope, or doing it in as few places as are needed is a good way of having a passive system which minimises heat loss.

    Aiming for simplicity can give good results

    Gwilym says that many of the high-performing homes don’t have anything particularly sophisticated in them. They just have a good design, controls that are simple to use and easy for the users of the building to understand.

    Some people can be fixed on the idea of having controls that link to their mobile phones, but actually it’s worth keeping things simple, particularly with a heat pump system, and not trying to have an overly fancy thermostat that is doing lots of clever control. And the same applies for lighting systems. Choose really good fittings, and then the controls can be nice and simple.

    Also, think ahead about choosing energy efficient appliances, IT equipment and access control systems.

    Be aware of annual and seasonal energy use

    Energy use in a Passivhaus tends to be mostly from domestic hot water, then space heating and plug loads. Improvements in LED technology has lessened the impact of lighting.

    As well as the the split between annual energy use, it’s also worth being aware of the seasonal variation, where in some ways it’s more attractive to save a bit of energy on heating, because that’s a lower carbon approach.

    Take advantage of the resources available

    Try to get an understanding of the principles early on and incoporate them into the design, which Gwilym suggests doing by accessing resources such as those from the Passivhaus Trust. He would also encourage getting involved with the Passivhaus community on Twitter and places like that, where people are friendly and happy to share experiences. It’s worth it for getting advice at the right time, rather than regretting it later!

    Max Fordham at home (photo copyright Lydia Goldblatt)

    Find out more

    Visit the website of Max Fordham

    Follow Gwilym on Twitter

    Visit the Passivhaus Trust website

    Cambridge University build student accommodation to Passivhaus standard

    Transcript

    Download a transcript of the interview with Gwilym Still

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  • HPH308 : Testing the thermal performance of a house – with Tom Fenton from Veritherm

    HPH308 : Testing the thermal performance of a house – with Tom Fenton from Veritherm

    Tom Fenton from Veritherm explains how to test the thermal performance of a home, what this data can reveal and how it can then be used.

    Interview with Tom Fenton

    Tom Fenton began his career working in the family’s design consultancy that focused on the envelopes and facades of commercial and industrial buildings. From this unique vantage point they were able to see the pitfalls in the design and construction process that impact on the performance of the building fabric, which led them to develop Veritherm’s test of thermal performance.

    Thermal performance measurement should be affordable and scalable

    In general, the construction industry’s understanding of thermal performance has been based on theoretical design assumptions and desktop modelling. Academic approaches to measuring thermal performance are lengthy, costly and complex, and only really used at a research level. Veritherm’s aim was to develop a solution that would be simple to use while being affordable and quick enough that it could be implemented at scale into a range of projects.

    Heat will find the weakest point

    Even in properties with high-performing materials and quality specifications like a Passivhaus, if the build quality or detailing isn’t quite right, then it will be sub-standard compared to its design predictions. Heat is like water and will always find the weakest point, which is where the energy will be lost.

    A phased testing approach can be beneficial

    The assumption is generally that testing would be carried out on completion of a new build home, but Tom says that actually, the retrofit market is accounting for around half of their business. Using a phased approach, an initial test will give a baseline measurement of the existing home and how it is performing. That information can be fed back to the design team to consider the most suitable fabric upgrades for the property, rather than relying on design assumptions. Further testing can then be used at other stages as new elements are introduced, to quantify the difference that eg, replacement windows or external wall insulation have made. A final test can determine whether the project goals have been achieved.

    A phased approach can also be useful on a new build, with measurements being taken before linings are installed. Together with further diagnostics, this can help to identify the possibility of any errors in the external envelope and allow them to be rectified before being sealed up.

    There are three phases to a Veritherm test

    The Veritherm test is carried out overnight and is broken down into three stages.

    The first step is to retrieve relevant design information for the property, such as its thermal specification and basic dimensional information, which is entered onto the Veritherm dashboard.

    Also in this preparation stage, the equipment is deployed in the property which includes temperature sensors in each of the habitable rooms, along with fans and heaters.

    During the measurement stage, the Veritherm platform activates the equipment remotely and a controlled and measured heat load is applied to the property, using the fans to ensure temperatures are rising uniformly throughout. It is heated for the first half of the night before then being left to cool passively for the remainder of the time. All of the heat load and temperature data is sent throughout the night to the cloud-based software platform, which uses its integrated algorithms to generate the results.

    On completion of the test the following morning the results are instantly available in a full report. This quantifies the rate of energy loss from a building per degree of temperature difference, expressed in units of watts per kelvin. The report also breaks down the data from the individual temperature loggers to give a better understanding of what is happening, and where, in the building.

    A Veritherm test is quite often carried out alongside other diagnostic tools, such as an airtightness test, so that you can understand what losses are attributable to air infiltration through gaps, and what losses are attributable to the fabric.

    Thermal imaging can pinpoint problems

    Veritherm’s test quantifies the rate of heat transfer, giving the average U-value for the building as a whole. However, if the test flags up any areas of concern, further diagnostics such as thermal imaging could be carried out to pinpoint anomalies.

    The performance gap can be quantified

    The Veritherm report compares the ‘measured’ data from the test, with the ‘designed’ data that was entered into the system in the preparation stage. This gives you a quantification of what that difference is between the designed and as-built performance, ie the performance gap. That information can for example be fed back to the architect to help them improve their design processes. If there’s a 400% gap in performance it might mean that the self-builder needs to look at considerably improving their envelope, but if it’s only 5% then that’s not going to make a significant difference on their fuel bills post-completion.

    The data that is produced can also be fed back into energy modelling software to communicate to clients what the longer-term impact will be on emissions and heating demand. This is particularly useful when it comes to designing heating systems to be correctly sized for the property. A new build property that doesn’t perform to its designed intent, means that the heating system may not be suitable or efficient. And conversely, many existing buildings have heating systems that are oversized in order to compensate for the unknown, which means there are many capital and operational savings to be had by getting it right and installing the correct system based on the particular property’s requirements.

    Also in the Veritherm report is a thermal efficiency rating, which is where the rate of energy loss is divided by the usable floor area. Using this traffic light style rating means you can compare for example a 5 bedroom house with a 1 bedroom bungalow, and identify where your property sits on that scale.

    The ‘designed’ and ‘measured’ data almost never tally!

    With the experience of carrying out these tests comes the knowledge that there is nearly always a difference between the designed and measured values. In general, new builds will tend to underperform against their designs. Existing buildings that use EPCs or reduced data standard assessment procedure (rdSAP) will pluck thermal values from standardised tables based on the building’s construction type and year of construction, to come up with basic thermal specifications for that property. Once measured, these properties will often outperform what was expected of them and the client can actually have a cost-saving on their planned improvement works. With upgrades being rolled out to millions of homes across the UK, Tom says that there is serious value and savings to be had by using a measured approach to retrofit.

    The goal is to have thermal performance testing in legislation

    Even testing identical properties on a development can throw up variable results and identify pitfalls in the construction process, in much the same way as when air tests were first introduced, showing why it’s so important for testing to be carried out.

    Tom is keen therefore for thermal performance testing to be included in Part L of the Building Regulations, and with the introduction of the Future Homes Standard which has a requirement for photographic evidence of insulation, he suggests that using a measured approach is actually of far greater value and a better way forward.

    Find out more

    Visit the website of Veritherm UK

    Follow Veritherm on Twitter

    Follow Veritherm on Instagram

    Find out more about Veritherm’s thermal performance test

    Transcript

    Download a transcript of the interview with Tom Fenton.

    Building Performance Interactive

    Ben Adam-Smith is taking part in a new series for Passive House Accelerator which aims to share lessons and best practice from low energy projects across the UK and Ireland. Hugh Whiriskey of Partel has devised the hour long format and is hosting alongside Ben and Mike Jacob of KISS House. The Building Performance Interactive is held monthly and everyone is welcome.

    Please connect with me

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  • HPH305 : Building a Passivhaus with cross-laminated timber – with Mick Woolley

    HPH305 : Building a Passivhaus with cross-laminated timber – with Mick Woolley

    Mick Woolley explains how the use of timber was a key element of his award-winning Passivhaus bungalow.

    Interview with Mick Woolley

    For the last two years, Mick Woolley has been living in his Larch Corner Passivhaus which was the Small Projects winner in the 2021 UK Passivhaus Awards.

    His self build journey began following the loss of his wife. He had long held an interest in self building and took the attitude “what could possibly go wrong!”

    To watch the documentary about Larch Corner go to PassivhausSecrets.co.uk

    He broadened his search area

    Initially beginning his search in the south east of England to be closer to his two sons in Surrey, Mick found a lovely plot, surrounded by a vineyard, and just 30 miles away from them. But despite the proximity, it had taken an hour and a half to get there and was £450,000 before he’d even knocked the existing bungalow down. It was at that point he decided to abandon his search in the south east and opened up to looking at sites as far afield as North Wales and Cornwall.

    They made changes to the planning designs

    Mick saw a plot on RightMove, that seemed to be in a pleasant village location at the northern tip of the Cotswolds. Close to a National Trust garden and Stratford upon Avon, he felt he would be able to find enough to do in the area and was surprised when he managed to purchase it for around the guide price at auction. It came with planning permission for a single storey Passivhaus with a design that he admits probably didn’t appeal to everyone, and is why he thinks there wasn’t more competition in the bidding.

    Although not put off by the design, he was sceptical of its Passivhaus credentials and enlisted Mark Siddall of LEAP to re-work the plans. He did however want to keep it a bungalow to make it accessible for a family member who uses a wheelchair, but also because it future-proofed it for him too.  

    The original design had a lot of corners so they removed some of these and also had to raise the roof to ensure there was adequate head height for insulation. They swapped the entrance hall and study around to ensure a better flow into the house, and took out the many corner windows from the plans. Mark instead designed an arrangement of windows that came in 2 sizes: smaller ones for the bathrooms and bedrooms, and larger windows with seating elsewhere.

    Timber was an important element of the design

    Mick wanted to build using Cross-Laminated Timber (CLT), as much for the visual impact it provided inside as for its structural qualities. The bungalow uses 17 sections of spruce timber, which have 6 layers, are edge-glued, and don’t require an airtight membrane around the outside.

    The roof came with a cassette of insulation in it so the structure went up in two days, and had an airtight wrap over the top by the end of the third day. The walls are made of an I-frame structure with blown-in wood fibre, giving a thickness of around 600mm and a U-value of 0.1.

    The exterior of the bungalow has larch cladding.

    The foundations were pre-cut to size

    The building has a Jackon XPS foundation which was pre-cut to the required size and slotted together, with an XPS upstand that locked into the perimeter. This created its own formwork for the concrete pour.

    The flat roof has a camber of around 5 degrees for shedding water. On top of the insulation is a cold roof section of ply and bitumen that provides the finishing structure on which to put the green roof. Mick says he checks up there from time to time just to check that seedlings for trees and other unwanted plants haven’t blown in and taken root!

    He was keen to be hands-on

    With Mick being on-site throughout the build process he was keen to get involved in any way he could, so one task that he took on was the airtightness taping. His top tip for getting it into the corners is to ideally bend the tape in two in order to push it in and get good contact right the way through the junction.

    The straight lines of the 17 sections of CLT only took an hour to do, but all the other joints around the doors and windows took a lot longer!

    Mick employed Alan Clarke as his M&E engineer and he carefully designed the ventilation system so it could go through cupboards and be kept out of the way, but still accessible if needed. The full design with all of the MVHR kit was supplied as a single delivery, and Mick took on the installation of the pipework himself. Not having any experience of doing something like that, he did find it took him a very long time to put together!

    There is around 140 square metres of floating floor, which was designed to be laid to flow through without any junction strips at doors. His builder Andy took time to work out the geometry to ensure that boards were centred and wouldn’t end up with slivers at the edges, which Mick was then able to lay.

    Always make space for storage!

    Although Mick was adamant that he wanted to use CLT, he now realises that he could have been more efficient with materials and created the timber finish that he was looking for by using large sections of three-ply timber.

    If he were to do the build again, he would probably opt for a two-storey building, though still keeping a downstairs bedroom. He says that the UK housing stock is generally fairly deficient in terms of providing for the elderly and those with mobility problems, so designing at least one bedroom downstairs is really important.

    Mick says that going for a two-storey design would improve the form factor and use a lot less insulation. It is also more efficient in having less foundations and roof.

    Lack of storage space is often a real problem in typical new build homes, but Mick is delighted at the amount of space they designed into his home, including a large storage wall. He also has a double garaged sized shed, although this is currently housing lots of off-cuts of CLT and three-ply materials that are waiting to find a home!

    He emphasises why it’s always a good idea to build into the loft as that’s also potential space that can be used for storage.

    Images copyright Mark Siddall LEAP

    Find out more

    To watch the documentary about Larch Corner go to PassivhausSecrets.co.uk

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  • HPH302 : A contemporary Passivhaus home in a rural context – with Martin McCrae and Mhairi Grant

    HPH302 : A contemporary Passivhaus home in a rural context – with Martin McCrae and Mhairi Grant

    Mhairi Grant and Martin McCrae share their self build journey. Their contemporary home seems to have it all, from striking design and great ecological credentials to high quality finish and value for money… but Martin and Mhairi had to work hard for it!

    Interview with Martin McCrae and Mhairi Grant

    Mhairi and Martin met back in 1997 when they both studied at the Mackintosh School of Architecture. Together they co-founded Paper Igloo, the architectural practice that they run from their home in Kippen, Scotland.

    They increased their land budget to find a suitable plot

    As speclialists in low energy design, and having lived in a beautiful but thermally uncomfortable flat in Glasgow, they made the decision to look for land and build a Passivhaus.

    After a couple of years of searching they realised that the £100,000 budget they had originally set aside for land wasn’t going to get them the plot they wanted: they were either too small, too remote, or not a suitable orientation for a Passivhaus. By upping their budget to £135,000 they were able to find their picturesque, slightly sloping, semi-rural plot that afforded them views onto open fields.

    The plot already had planning consent for a traditional house, but they submitted new plans for their contemporary cube which were approved following a little bit of resistance.

    View of the plot

    With a budget of £250,000, they knew sweat equity would be needed!

    Mhairi admits that they probably weren’t aware quite how much sweat equity would be involved, but she considers the learning from it to be all part of the journey and not something they regret!

    “Building a Passivhaus isn’t as daunting as some people make it out to be. I think it’s just a matter of doing things correctly in the correct order and rigorously looking at the detailing.”

    – Martin

    Initially, Martin took 12 weeks off from their business in order to get the build underway, working with two joiners to erect the timber frame. As it’s just the two of them in their practice, this did mean a drop in income for a time, and one of the reasons the project took so long was because they had to balance their finances by earning money as they went in order to finance the build.

    What they originally thought might take two or three years, actually took six! And this was at the expense of their social life over that period as much of their free time was spent working on the house.

    They had strategies for managing the challenge

    At the halfway point they were thinking it was starting to drag, so keeping their energy up was challenging. Taking the cladding as an example of one particularly wearing period, they did it themselves over the space of four years, with each elevation taking an entire summer to complete.

    Mhairi says it was important to keep reminding themselves of what it was they were trying to achieve, and that it would be worth it in the end. In the same way they would approach any dauntingly large task, they broke it down into smaller tasks, tackling each one before moving on to the next.

    Martin adds that it is a technique they use for coping with stress at work too, and it helped get them through the long build process. He also says that being in it together made a difference.

    Supplier issues and design decisions were interlinked

    Their plan was to create a simple and clean design that would allow them to easily meet the Passivhaus standard, but also sustainability gold and technical standards in Scotland. That incorporated a further set of criteria to do with water-saving and acoustic performance.

    They knew that they wanted to use a timber frame, but struggled to find a supplier who could provide a Passivhaus-ready or kit solution. That was why they ended up stick building the frame, and why Martin says that decisions like that can lead you to design decisions.

    The pace of building slowed once the frame had been completed

    They employed someone to do the groundworks but installed the Isoquick EPS raft foundations themselves, with the help of friends over a weekend.

    After the concrete was poured they were able to start on the stick frame.

    Once the joiners had finished the frame, Mhairi and Martin took over the workload. They spent the next four months taking as many days off work as they could, plus evenings and weekends, working on the wall installation, hand-cutting, and fitting the wood fibre batts.

    They tried to be resourceful, not wasteful

    Martin and Mhairi were careful to minimise the amount of waste that left the site. They were able to relocate the excavated earth to other areas of the garden, and in doing so were able to create a flatter garden with drop-down terrace towards the barn.

    They were also very diligent about buying materials with as little packaging as possible. Plastic was recycled where possible, pallets were broken up into firewood for Mhairi’s dad, and off-cuts of wood fibre insulation were stacked rather than having to use new pieces. They were rigorous too about how to cut and use the plasterboard in order to minimise waste, and were left with only four A3 sized off-cuts from the whole build. With such little waste, they were able to just take it to the tip, rather than needing a skip. This also had cost savings, though they do agree that it did mean it all took a bit longer.

    MVHR Ducts

    Living in a caravan was incentive to keep the project moving!

    Having sold their flat, they rented a couple of different places in the village before finally moving into a caravan for the final nine months. Living in a two-berth van, with the water freezing over the winter and an electric bar heater on permanently to try and stay warm and dry, in what was also their office, did focus their minds to crack on and get moved in as soon as possible! They managed to get one room ready first where they could sleep and work while they finished the rest of the house. At the point when they moved in, they had their electrical completion and were plaster boarded in most of the house, but were using a sheet of OSB as a kitchen worktop. They didn’t have their linoleum or timber flooring down upstairs either and were just at the acoustic flooring stage.

    The double-height space adds impact

    Right from the beginning, they wanted to incorporate a large, double-height space into the design, and this meant a change to the wall construction at the double-height area compared to the single-height area. With Passivhaus, most things are ratified against the floor area, so the decision to have a double-height space can impact on your insulation and window specification for example.

    Rainwater has a visual journey through the garden

    Part of the sustainability gold section in the technical standards in Scotland is about water-saving measures. To meet this criteria, they have used low-flow fixtures and fittings on all their taps and showers. They attenuate about 40% of the rainwater from their sedum roof, and only have one rainwater pipe for the whole of the flat roof area.

    That takes the water on a journey down off the building and into a catch-pit of stones, along a trough and into a rain garden – an elevated planter in the garden with plants that are suited to being saturated or very dry. The overflow from that goes to the barn at the bottom of the garden.

    Renewables have been incorporated

    The 1.5kW array of PVs on the roof is enough to run the dishwasher and washing machine, and pays for itself. A solar thermal array makes a massive contribution to their hot water needs, and almost more than they need in the summer.

    Infrared panels are on the ceilings of the living room, kitchen and one bedroom, and also at the top of the double-height void. They radiate heat down onto surfaces like the concrete slab, which then themselves release heat.

    Passivhaus comfort levels have exceeded their expectations

    In fact, Mhairi and Martin say it is so amazing to live in that they have spoiled themselves, because they really don’t want to live in anything else now that they have done this!

    They also find it very easy to live with too, with very little interaction with the technology.

    Being a Passivhaus they had been very careful about how much window they designed on each elevation. They knew they had a higher risk of overheating in their bedroom, which has a fixed, large, west-facing window and then a smaller opening window. As they were going to be the end users they decided they were happy to interact with the building in order to keep the design they wanted and prevent overheating. During the summer they do purge heating at night by opening the shower-room roof light, open the bedroom window on tilt and leave the en-suite door open. They also have opening windows in the upstairs and downstairs halls for cross-ventilation during the day.

    Their experience of building and living in their own Passivhaus has led to them making a commitment in 2020 that Paper Igloo will only design their new builds to the Passivhaus Classic standard as a minimum.

    Make sensible decisions at every turn

    Maintaining a spreadsheet was helpful for Mhairi to keep control of the budget. Every week she would take the bank statement and rigorously check what things had cost against what they had predicted they would cost, and then adjusting how much they had left to spend.

    Martin’s tip for anyone doing some of the building themselves, or if the budget is limited, is to get someone else to make the shell wind and watertight as quickly as possible. This will mean the building won’t start to deteriorate from the weather, and you’re free to take your time with the rest.

    And finally, do as much research as you can. This applies in terms of funding, materials, construction options, etc. There are generally lots of options out there so there is no need to go for the first thing you come across. Then make sensible decisions at every turn, as even the small amounts add up.

    Find out more

    Visit the website of Paper Igloo

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    Transcript

    Download a transcript of the interview with Martin McCrae and Mhairi Grant

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