Elly Deacon Smith and Kirk Rushby from Arbor Architects explain why they consider the embodied carbon of their projects, how they do it and how it is balanced with competing factors.
Interview with Elly Deacon Smith and Kirk Rushby
Elly Deacon Smith is the Founding Director of Arbor Architects with nearly 25 years of experience. She began her career in Bristol at White Design, working on straw and timber projects that emphasised both embodied and operational carbon long before it became mainstream. After moving back to Herefordshire, she joined Architype, deepening her expertise in Passivhaus construction and building physics, before co‑founding Arbor Architects, which she now leads.
Kirk Rushby is an Associate at Arbor Architects with roughly 20 years in the field, fifteen of which were spent at Architype. His background mirrors Elly’s focus on sustainable, low‑energy design and bio‑based materials. He’s also built his own Passivhaus home.
Focusing only on the energy a building uses in operation misses a large portion of its climate impact. Embodied carbon covers emissions from material extraction, manufacture, transport, construction and demolition. Even a Passivhaus can carry a substantial carbon debt if high‑impact materials are used. Measuring both sides lets designers keep total lifetime emissions within targets like the RIBA 2030 benchmark.
“We’re aware that operational carbon is regulated, but embodied carbon is a bigger blind spot,” Elly notes.
Make sure your design team is carbon literate
Elly taught a master’s course at the Welsh School of Architecture. A key aspect she encouraged was to “think in carbon” for every decision. This habit makes it easier to spot high‑impact choices later, because the designer already asks, “What is the carbon cost of this material?” Kirk agrees that years of practice have turned this questioning into second nature. Early education therefore lays the groundwork for systematic carbon reduction and intuitive decisions.
Use specialist tools to quantify embodied carbon
Arbor initially hired an external consultant to run assessments in PH Ribbon, which can use a certain amount of information from the existing PHPP model. The consultant just required quantities for elements like walls, floors and roofs, enabling calculation of kilograms of CO₂ per square metre. More recently Kirk is using a tool from Studio Bark, whose emerging calculator pulls volumes directly from Revit models, delivering near‑instant feedback.
“We’re really keen to be able to model in‑house, and to be able to make decisions quite quickly,” Elly explains.
Tin Barn
Take advantage of real‑world case studies
Arbor’s retrofitted Tin Barn (certified to the EnerPHit standard) achieved about 347 kg CO₂ / m², comfortably below the RIBA 2030 target. By contrast, a newly built garden‑room annex with timber framing and zinc cladding recorded just over 600 kg CO₂ / m². Interestingly, adding a photovoltaic array increased the figure by roughly 100 kg CO₂ / m². Elly says that this is another good reason to take a fabric first approach so that you keep your energy needs to a minimum.
Cwm Barn
Test assumptions: zinc cladding may not increase carbon dramatically
Swapping timber cladding for zinc on the Cwm Barn garden‑room added only a modest amount of embodied carbon, perhaps contrary to expectations. Elly attributes this to the relatively small surface area and the fact that the underlying timber structure already contributed most of the carbon.
“One of the surprises was that the decision to clad the garden room in zinc didn’t have as big an impact as we thought,” Elly comments.
So the lesson is to evaluate material impact in context rather than doing it intuitively.
Quick checks, early in the design process, make it possible to consider embodied carbon for every project
Waiting weeks for external consultants slows down design decisions and is not practical in the long run. So using a simpler embodied carbon tool like the one from Studio Bark means the whole process becomes easier, different options can be evaluated and it can be integrated into the standard workflow.
Using bio‑based materials normally leads to a good carbon outcome
As a general rule at Arbor they like to build with timber. This stores carbon from the tree’s growth, giving it a lower embodied carbon compared to other methods of construction.
Recognise foundations and substructure as the biggest carbon hotspot
Concrete foundations are inherently carbon‑intensive and often difficult to get away from. However, you can reduce volumes with good design or use low‑carbon mixes. Sometimes screw piles can be a way to avoid concrete altogether but these will normally be made of steel which again has a high embodied carbon. That said, they can be removed and reused at the end of the life cycle.
Balance cost, client expectations and carbon goals early on
High‑performance homes and Passivhaus certification typically increase material quantities and costs a little. Arbor addresses this by being transparent with clients from the outset about trade‑offs between carbon performance and budget. Early budgeting conversations help align expectations, and designers explore “more with less” tactics—optimising layout, trimming unnecessary floor area, and selecting durable, low‑maintenance finishes that lower lifecycle costs. Kirk stresses that “you can get more out of less” with the right mentality.
Good decision-making considers many factors
Embodied carbon is just one aspect of a sustainable home. Arbor evaluates each material for moisture handling, indoor air quality contribution, longevity and visual ageing.
Designer experience and instinct are still important
For design teams that aren’t yet modelling embodied carbon, logical decisions can often lead to low carbon outcomes: prioritise low‑impact substructures, favour timber over masonry where feasible, reuse on‑site materials, and keep use of steel to a minimum.
Anticipate a future where measurement is seamless and data is shared
Whereas many design teams are familiar with operational carbon, the future could see quick‑feedback calculators embedded in standard workflows and a shared database of embodied‑carbon benchmarks for common building typologies. More data will enable designers to make confident, low‑carbon decisions early in the design process, accelerating the transition to a net‑zero built environment.
Chris Brookman from Back to Earth explains what wood fibre insulation is, how it could be used on a project and why careful specification is required.
Interview with Chris Brookman
Chris Brookman, founder and owner of Back to Earth explains how his chemistry degree has been put to good use within the construction industry. His experience ranges from working with natural cob to examining the properties of different building materials to create specifications for particular needs. He has built his own Passivhaus and here shares his technical understanding of wood fibre and the many properties it offers for buildings.
Chris working on a cob building
Traditional cob building is strenuous
Straight from university Chris worked as a cob builder. He explains that traditionally cob was a combination of clay, sub soil and straw mixed together by cattle treading over it to make a plasticine kind of mix, that was stacked on top of a low stone wall. These days sands, grits or aggregates might be added to adjust the properties of the mixture. One of the reasons Chris eventually moved on from cob building was because the nature of the work was extremely physical.
Traditional materials can play a part in modern construction
Chris then came across wood fibre, which worked well with cob and that got him interested in learning more about different materials. He was particularly interested in finding materials which have the properties of traditional materials, but are in a modern format, so are easy to use by a modern builder. He eventually moved away from the building business to create Back to Earth, which deals with the specification and supply of materials.
Wood fibre is not just about thermal insulation
For Chris, thermal insulation is only one of the reasons for using wood fibre products. Alongside this it offers acoustic insulation, thermal mass to help reduce summer overheating, and good fire resistance. It is also locking up carbon for the duration of its lifetime, which is really important.
Wood fibre products start with waste timber
As a by-product of the timber industry, the production process for wood fibre starts by grinding up the waste timber to fiberise it, which is then treated in one of two ways.
The wet process uses the natural lignin to bond the product
The more traditional process is to mix it with water and detergents to create a slurry, which is then put on a conveyer belt to strain all the water out, before it is compressed and steamed. Through steaming, the natural lignin glues the fibres together, producing a board around 20mm thick.
The dry process uses a small about of glue
The more modern way is the dry process, which uses a polyurethane-based glue to stick the fibres together. You blow the fiberised wood with the glue, compress it to the right thickness and density before curing it with warm humid air. This creates an homogeneous product, from 20mm up to 200 mm thick.
The dry process makes a lower density product, which is a bit more rigid and has a lower thermal conductivity. However, it massively reduces the amount of energy used to make the product and is slightly cheaper to make. As it only uses a small amount of glue, maybe 3-4%, it has a minimal effect on moisture retention. Most boards are made in this way now and whilst it can be better to use wet processed boards for internal wall insulation they can generally be used interchangeably.
The density of wood fibre can be a benefit over other natural products
Chris explains that he chooses materials based on their properties but, in most scenarios, natural fibre products tend to work better than synthetic materials. Common uses include insulating timber frames, roofs or internal walls.
The density of wood fibre is also a useful characteristic when it comes to adding thermal mass to a building, which in turn absorbs the heat more slowly and can make a big difference to summer comfort. This is one key difference to most other natural fibres.
Building new made it possible to create an accessible home
Chris’ first son was born disabled and it quickly became apparent that the small rooms of their old cob house were not going to work. The house was over three floors with no circulation space for a wheelchair, so they started thinking about building a new house.
A Passivhaus would provide a good environment for his disabled son to stay warm
Chris recalls that John Williamson, in Wales, had just built one of the early Passivhaus projects. He was also aware that when you’re sitting in a wheelchair, your environment needs to be warm.
Bricks from the bungalow are reused as hardcore for the new house
A specialist architect provided input on the designs
In 2011 they found a suitable site, with a 1950s bungalow they planned to demolish and use as hardcore for the new build. Chris explains that they hired a specialist architect to look at their designs and make suggestions about circulation space, door widths and accessibility over the whole site. The whole plot was levelled as a consequence, with just a slight fall to help water drain away, all the thresholds are level.
The office was built before the main house
The office was built first to test their approach
Chris worked on the detailing for the build, but it was a friend who carried out the construction. The office was their test case, and they made a few minor mistakes which meant they were just over the 0.6 air changes per hour at 50 Pascals required to meet the Passivhaus standard. This meant that when it came to the main house they really focused on airtightness.
They used a timber frame filled with wood fibre insulation, which was relatively quick way to build. An airtight OSB was used internally as the airtight layer.
Clay boards were added to the internal walls to improve the acoustics
In a Passivhaus you need to have a little gap under the internal doors to help the air flow, but that can cause issues with sound transfer. So Chris used clay boards on all the internal partitions to improve the acoustics.
Where structural, the internal partitions have Fermacell on one side and clay board on the other. The non-structural partitions have clay board on both sides with flexible wood fibre in between.
The clay boards have given the added benefit of increasing the thermal mass of the building, so help to reduce summertime overheating.
All new builds have a few niggles
Chris and his family are really happy with their home but there were few things aspects they were keen to address. The biggest mistake they made was with the front door, where they cut a metre wide opening into the frame, but hadn’t realised the thickness of an external Passivhaus door. So they ended up with an opening width of 740mm which made it difficult to get in and out with a wheelchair. This was, however, changed a few years ago so now they have a 1300mm wide opening.
They also swapped two of their clerestory windows to ones with electric openers to make it easier to purge ventilate in the summer. Chris had initially thought the MVHR system would be able to deal with this but it wasn’t enough on its own.
Something that couldn’t be changed without substantial work was the liquid screed floor finish. They had intended to use underfloor heating tiles, but they were too expensive, so they used liquid screed instead. Chris regrets this choice as this floor transmits sound right across the house.
One other regret was connecting the house to the gas main. Not only was it expensive to install but at the time grid electricity was about 500 grams of CO2 per kilowatt while gas was 180 grams of CO2 per kilowatt, so using gas to heat the home seemed like a good option. Chris may well switch his heating source in the coming years.
Back to Earth’s specifications ensure their materials will give the right results
Chris sees the primary role of Back to Earth as creating specifications for materials to ensure they achieve the best results on each construction project. Most of their work is on retrofit projects and they use WUFI to model the specifications they are producing.
A WUFI analysis of a specification
Chris sees them as problem solvers, looking at specifications to provide the right material for a particular function. His own construction experience also means they can add in practical details alongside the specifications.
The Fibres Academy training platform
Chris believes a lot more people would use natural materials if they understood them better. To that end, Back to Earth have just revised and relaunched their Fibres Academy training platform. This is free to use and gives you access to courses, 3D model and installation guides to help you use the materials with confidence.
Chris tells us that Europe is a long way ahead in the amount of natural fibre materials that they use. Figures from a few years ago showed Europe’s use of natural fibres at around 10%, whereas in the UK we’re struggling to reach 1% of the market share. There is a fundamental difference in perception and accessibility between the UK and Europe. Back to Earth’s training platform is trying to improve people’s understanding of the products to increase use and push forward this agenda.
Generally as a share of the market, Europe is using about 10 times more natural fibre than we are.
Natural fibres are generally a bit more expensive but worth it
Natural fibre products may be slightly more expensive, but for Chris it is like comparing apples with rotten eggs. People might say why use wood fibre instead of PIR? But often the installation of PIR isn’t good. It may just be wedged between timbers, resulting in air gaps opening up later and reducing the performance.
So often the perception is that modern materials are cheap, but this can be because the time is not taken to install them correctly. Back to Earth give detailed guides, going through all the airtightness layers and the whole build up. This ensures correct installation so the product works.
It’s also important to recognise the value and added benefits that you get with these materials. It’s not just about cost, there’s the environmental impact, the health of the installers and the health of the occupants years down the line, along with the longevity of the building and the finishes.
A change in attitude and better regulation is needed in the UK
Chris feels we have a different attitude to our housing than the rest of Europe. We’ve commodified housing, so we buy and sell with the expectation that we will make money from our properties. If people actually proiritised comfort and health, they would probably steer clear of major developers and make different choices.
The building regulations also have a role to play in increasing the use of natural materials and better legislation from the Government would have a big impact. Government should not be a passive overseer, but be there to guide people’s activities, which could make a big difference in the emissions from the construction industry. This could include an assessment of the embodied carbon of products and the biogenic stored carbon. The locked-up carbon in wood fibre, may only be for the lifetime of the product, but surely that’s better than it not being locked up now.
Lloyd Alter explains the term upfront carbon, its relevance to us all as consumers, and why he felt compelled to write a book on the topic.
Interview with Lloyd Alter
In 2021, Lloyd released his book Living the 1.5 Degree Lifestyle, where he attempted to limit his carbon emissions in line with what climate scientists say would be needed to keep within 1.5 degrees of global warming. Lloyd took on this challenge just as the Covid-19 pandemic struck and therefore it might have been slightly easier than normal because big emission activities such as flying were restricted. After completing a year living within this carbon budget, Lloyd stopped carbon counting. Habits that stuck include eating more vegetarian meals each week, using his e-bike instead of his car as much as possible, and not buying gadgets on a whim. The trickiest part for him has been air travel and he has taken a few flights since.
After examining the power of our personal choices Lloyd’s latest release focuses on our obsession with stuff! In his new book, The Story of Upfront Carbon: How a Life of Just Enough Offers a Way Out of the Climate Crisis, Lloyd explores the carbon emissions linked to everything we purchase as consumers.
“If you buy a car you’re buying 14 tonnes of upfront carbon emissions, the emissions of making that car. Everything you buy has these issues and people would talk about efficiency, efficiency, efficiency. But efficiency is pointless without sufficiency.”
What is upfront carbon?
When it comes to producing products a common phrase used to describe carbon emissions (or greenhouse gas equivalent emissions) is ’embodied carbon’. However, the word embodied is misleading in this context as it seems like it is describing a positive process of carbon sequestration rather than a harmful process of emissions. Lloyd, alongside Elrond Burrell and Jorg Chapastarted thinking if it could be described more accurately and came up with ‘upfront carbon’. This term clearly highlights to the consumer what the carbon cost has been to create a product up until the point of purchase.
Upfront carbon refers to the first 5 stages of the life cycle (production and construction) from A1 to A5 which goes from the mining of materials right up to the use stage. It can be difficult to find accurate information within different aspects of the supply chain which makes most calculations an estimate rather than a certainty. Lloyd highlights that in spite of this uncertainty, it is always a good idea to use as little resources as possible as this will reduce the upfront carbon. It is also important to focus on items that use less processed materials because the upfront carbon will be significantly lower, so a wooden pencil rather than a metal mechanical one, or straw insulation over foam.
“The ultimate thing is just how much of everything are we using”
Upfront carbon is a good place to start but can’t be the end
Upfront carbon tells us a story about the production process of that object and can highlight the impact that the mere existence of the product has on our planet. However, with many of the things we buy, we will also generate carbon emissions when we use or maintain them. The easiest example of this is a car, which comes with approximately 14 tonnes of upfront carbon, but if that car has a petrol engine with poor fuel efficiency, the carbon emissions will be ongoing. It is therefore important to be looking at both the upfront carbon and the entire lifecycle of the product, in order to understand its impact and determine whether it is worth purchasing in the first place and how best to manage it.
“I had a student who actually analysed a pencil for her class. It was a brilliant, brilliant examination because the Staedtler pencil was made in Nuremberg, from clay from Pennsylvania and graphite from Turkey and cedar from California. And all of these things came together in a pencil in Nuremberg, which was shipped to the store in Aurora, Ontario, North of Toronto. But the carbon emissions from her driving to the store and bringing it home were twice as big as the whole manufacture of the pencil and shipping everything all over the world.”
Buy good quality things and maintain them for as long as possible
Every time you buy something new it comes with upfront carbon. Every year you can make that product last, you are amortising that upfront carbon over a longer period and it will be getting less and less. Lloyd highlights this as the simplest method for reducing your carbon emissions and by breaking that consumerist mindset, you will be taking a large step towards a more sustainable lifestyle.
Use materials that have been processed less
Lloyd highlights that another way to ensure you are reducing your upfront carbon is to use natural materials where possible. The majority of building products that have been highly processed will have extremely high upfront carbon, items like foam insulation or concrete. Lloyd uses an example from Steve Webb:
“He said, how do you make concrete? You take limestone, you grind it up into a powder, you put it in a kiln at 1450°C. You then mix it with a bit of clay and aggregate to make what is basically artificial stone. So if I go to a quarry, cut out the limestone, cut it into blocks, drill a hole and put a cable through it as reinforcement, I can make a beam out of stone that is stronger than the beam out of concrete with a 10th of the upfront carbon emissions and it will last five times as long. I said why aren’t we doing this? Making concrete is perverse.”
Minimally processed materials must be used in the most efficient way and all while keeping a check on the scale of things. Lloyd indicates that there is often a misconception that if wood sequesters carbon, then using as much as possible can only be a good thing. However, this negates the fact that wood is a precious resource and whilst it is a great natural building material with low upfront carbon, it should be used as efficiently as possible within the structure.
While much of the design world ignores the wisdom of optimising, the path is clear. For example, for larger timber buildings they would be simple and boxy, and limited in height to around 6 storeys. The buildings would have flat facades and fairly small windows.
“We should stop this insane competition to be the tallest wood building in the world. You don’t want to be the tallest wood building, because then the columns are getting bigger and bigger and bigger, and you’re putting in more and more fibre. And you’ve got to deal with harder fire regulations and all of these things.”
Finding out accurate information about the upfront carbon can be difficult
You cannot accurately measure the upfront carbon of wood because every tree is different and unique. The most important thing you can do is make sure you only use FSC certified timber.
Both high energy efficiency and low upfront carbon must be prioritised
The construction space can be filled with confusing examples. Many of the first really efficient houses used foam insulations with huge amounts of upfront carbon, so whilst carbon emissions were reduced on a day to day basis, they were significant during construction. An opposing argument has been raised from within the eco build community, where natural building materials with low upfront carbon have been prioritised whilst the need for energy efficiency has been questioned. Lloyd believes that both must be considered equally to ensure that our homes are as sustainable as possible whilst also providing comfort and security.
There may be emissions from heat pumps
The refrigerants used in heat pumps often contain harmful greenhouse gases and so if the heat pump isn’t installed correctly they may leak. There are now some heat pumps that claim to use ‘natural’ refrigerants but in reality they are still fossil fuels, just natural gasses rather than fluorocarbons. The ‘natural’ heat pump is a much less harmful version and should definitely be prioritised where possible, but it is not necessarily emission free. Because of this nuance, once again, it is important that the spaces we are designing are modest to ensure that we can keep the size of our heat pump down and therefore reduce the associated emissions.
Lloyd highlights that there is a growing need to design buildings with future grid intermittency in mind. This would include low carbon, well insulated and efficient shells in order to maintain indoor temperature in the possibility of power cuts. With a need to move towards more and more renewable energy sources, it is important that we anticipate the potential issues that could arise and plan around them. Lloyd highlighted a potential to connect up car batteries to houses in order to utilise each of our resources to the max.
“The thing about this new world we’re getting into where we’re relying on renewables for everything is that renewables are intermittent… We have to design our houses to be really, really efficient so that if the heat goes off for an hour, and the hot water heater goes off, you don’t notice it.”
Cultural shifts can cause a ripple effect that increases our carbon emissions
Lloyd uses the example of the hamburger as a cultural ripple effect. The rise of fast food and drive thrus has created a culture around eating inside our cars. As a result car manufacturers began to add in features such as tray tables and cup holders to make this experience easier for the consumer. As years go by, these features increase and the overall size of cars increase too as a response to the amount of time we are spending in them. All of these increases go far beyond sufficiency and enter the world of excess, where every extra feature and every extra inch of space is adding to the upfront carbon of the car. This is a great example of how our cultural and consumerist influences cause these ripple effects that amplify our impact on the climate at every stage.
Copyright Looney Tunes
‘Visualising’ the carbon may help us grasp its impact
Lloyd spent a long time deciding on the best metric of measuring upfront carbon and eventually settled on Wile E. Coyote’s biggest threat, an anvil. It can be difficult to grasp the real impact of upfront carbon when it is measured in pounds or kilograms. Therefore being able to say that the production of a Macbook Air took an anvil and a half of carbon or that a watch was half an anvil can be a really valuable image to help people understand the true impacts of their possessions.
Could a ‘carbon allowance’ be the answer to sufficiency?
Lloyd suggests that carbon rationing could be a good strategy to help reduce carbon emissions. Everyone would be allowed the same, whether that’s by year or by lifetime, and from there they are free to decide what to spend their allowance on. The idea is that the consumer would be encouraged to reflect on the impacts of the products they buy and the choices they make.
“So if you’re building lower cost housing, you could maybe say slightly lower standard because it’s small. But if someone wants to build 500 square metres and has the same carbon allowance, they’re going to have to really be careful and they’re going to have to build it to a really high standard. And then if you start saying oh, by the way, you’re only allowed to have this much carbon allowance to build your whole house. Well, then they’re suddenly going to be looking at saying the only way I can build my mansion is if I build it out of straw and hemp on woodpile foundations.”
Sufficiency, sufficiency, sufficiency: how much do you really need?
“In this new world of upfront carbon, we have to turn that on its head and start thinking about sufficiency. How much do we need? And this goes through everything. How much clothing do I need? How much food should I be buying? How big is my car? Do I need a car? How big is my house? Everything we do we should look at it. And I often say when you look at the world through the lens of upfront carbon, everything changes. You just start thinking differently about everything you do and everything you buy.”
Janice Gardiner, an ecologist and the client of last week’s interviewee Josh Wood at Green Trace Architect, is here to tell us what it is like to be the client on a Passivhaus project and share what she has learnt from the experience.
Interview with Janice Gardiner
Janice Gardiner is a nature conservationist and alongside her husband Colin has created the beautiful Hazel Tree House. After having their youngest child leave for university, Janice and Colin decided that they wanted to downsize from their 4 bedroom, victorian terrace house in North Somerset and embarked on the adventure to build an eco home in the Herefordshire countryside. After moving in just over a year ago, the house is living up to all of their expectations and even surpassing them, after recently winning the Best Eco House at the Build It 2023 awards.
In this chat, Janice talks about what it’s like to be the client in a Passivhaus build and shares with us all of the lessons she has learnt along the way.
Finding the site
Janice and Colin had been looking to downsize and originally their search had included houses or renovation projects in the area close to Ross on Wye. But when they discovered a former pub garden with outline planning permission, they began on the new-build journey instead.
“We’d done up a victorian terrace for 20 years, so we were constantly looking after the house and making improvements. So we actually want a house that will look after us.”
The site is just under an acre in size and includes the house plot, overlooking an orchard and also a field behind, that Janice is using her knowledge of wildflower meadows to manage.
“We’d always looked at Grand Designs and we’d always thought we’ll never do anything like that. And I think it was just seeing it in a place that we were considering we just thought well, let’s have a look and see what’s possible!”
Start with clear intentions
As an environmental conservationist and ecologist, Janice states that it was always going to be an eco-house; in the materials that it used and level of energy efficiency. Although initially they thought that they wouldn’t be able to stretch the budget to meet Passivhaus standard, there was an ethos of sustainability from the start. Having this clear intention allows you to create a team that possess the knowledge and skills that are in line with these values and will provide a strong structure for your build before you even broken ground.
“We wanted it to be eco so that was one of our criteria to start with. My backgrounds in nature conservation, so the environmental side and the ecology side was very much there. Then because we knew we wanted an eco build, we started looking for architects that had those credentials.”
It is crucial to find the right team
Because Janice and Colin began the process with clear intentions, they were able to assemble a team that had the same shared values and the qualifications to put them into practice. Being from around the Bristol area, Josh was recommended to them by another firm and they began the talks with him.
When it came to finding a crew for the actual build, Janice was able to draw on the large community of eco builders in Herefordshire and as a result found Dai Rees, a local Passivhaus builder. He was the project manager and the main contractor, and having his expertise working alongside Josh’s designs helped the build run smoothly. The team he put together was also quite special as they were all builders who had an interest in Passivhaus and eco builds, so were eager to learn and put their own special touches into the house.
This strong team shows that the overarching ethos of a build will help you find people who share those interests, and through their passion for their work you will together create something really special!
“I think you should try and enjoy the whole process and I think there’s something about working with people that you have a good relationship with. What I found lovely about doing an eco build is that because people are doing what they’re interested in, you’re all trying to achieve the same thing. There’s a bit more of a meaning behind it for all concerned.”
The planning stage is not to be rushed
At the beginning of the build, they didn’t think they had the budget to build to Passivhaus standard. Josh then came on board and was able to not only provide the design and technical drawings, but also present the different build methods and materials that could get the house close to that standard. An architect acts to guide clients through the sea of information that can be overwhelming if you haven’t done this before.
Josh provided Janice and Colin with an excellent feasibility study that helped them see the larger picture in relation to their site, planning and construction methods. They also sat down and identified what characteristics they were looking for in their house; how they wanted to live within it and how it would make them feel. The exercise highlighted that Janice and Colin wanted a modern but modest eco home which promoted simple living with a sense of joy and calmness.
“I think he was then our guide as to the method of construction and all of the design of the house. But he did a really good feasibility study with us in terms of what it is we wanted and how we wanted to live”
Planning restrictions can be a license for creativity
Within the planning permission for Hazel Tree House there was a restriction that it couldn’t be larger than 100 metres squared internal floor space and limited the house to two bedrooms. This meant there was a need to creatively design the space to get the most out of the size restrictions. Josh was able to work within these limitations by including a void area over the open plan living space that allowed for the house to feel bigger without going over the floorspace restriction. In addition, the upstairs of the house is situated under a pitched roof, and within planning regulations anything that is under eaves that are lower than around 1.5m is not included in the floor space calculation. This restriction ultimately led to space being used as efficiently as possible and added features that maybe wouldn’t have been considered without it there.
Outline planning permission can offer a lot of freedom
At outline planning the previous owner had not submitted a detailed plan for the build and as result there was a very standard outline of a two-bedroom house with 100 metre square internal floor space but no other details that were specified. This meant that they had quite a lot of freedom in terms of design and style as long as their new plan met these guidelines. This included moving the overall position of the house further back in the plot, in order to save a large Hazel Tree from being removed, which later became the design inspiration for the house, a crucial factor in keeping the house cool in the summer and the house’s namesake.
The build system
Hazel Tree House is constructed on an Isoquick raft with a poured concrete slab. It is a timber frame structure using I-joists with walls made from blown cellulose insulation sandwiched between wood fibre boards. The roof and half of the external walls are clad with black corrugated metal with integrated gutters and the other half with cedar panels. The windows and doors are all triple glazed from the Green Building Store and the internal walls are finished with clay plaster. Due to the very efficient way that materials are used, the house has a negative embodied carbon score.
Due to delays in planning as a result of the Covid-19 pandemic, the whole process took a total of 2 years, from buying the land to moving in, but the build itself only took 9 months of that time.
Where to save and where to spend – bespoke vs standard features
Janice talks about how you may start with the simplest design intentions but when you are given other options that are maybe a bit more interesting but add to the cost it is difficult to not be tempted. The pay off is in what they offer you or the joy they give you.
“A straight A frame shape would have been your simplest form and your cheapest form. Josh came up with the idea of lifting part of it to create this opening and this veranda. Once you’ve seen that, it’s very hard to just look back. So I think that is the thing that happens. You’re on a creative journey with your architect, and then with your builder. Some of the joy of the build is in doing those things, rather than sticking with just what you’ve said and just what the budget is maybe dictating. So I think your personality comes through in the decisions you make there.”
Janice shares that Hazel Tree House’s signature round window added expense to the project and caused a few headaches when it came to installation and the creation of an external window sill. When building a Passivhaus, airtightness is crucial and unusual shaped windows can be areas where gaps can be created. There are ways to avoid this and with some bespoke and creative carpentry, solutions were found. Janice says that despite the added challenges that the round window created, she is very glad they decided to do it as it is very worth it for the character it gives.
The tin cladding is actually an example where Janice and Colin decided to save money. They had originally looked at dark grey cladding panels which were significantly more expensive than the black corrugated metal they ended up choosing. But in fact, the cladding that they decided to go with adds a beautiful structure to the back of the house and hints to the agricultural buildings that it shares the landscape with. This is an example of where the more expensive option may not be the best for you, and it is aways good to refer back to your intentions for the build: does the material or feature align with them?
“We did stretch ourselves because the things that we said we can’t afford, like the solar panels and Passivhaus certification, were things that we really did want to do and we really did want that quality of finish. So, I think you can say to yourself, I’m not going to do it. But actually, once you’re doing the build, and really involved in that process, you’ve got to be very strong to not go with what your heart actually wants.”
Is Passivhaus certification worth it?
In the case of Hazel Tree House, the aim had always been to get it to the highest standard of energy efficiency that they could, including an MVHR, triple glazed windows and a very high standard of blown cellulose insulation. It was only during the build that Janice and Colin decided to go the whole way and get the passivhaus certification as well. This is not an essential extra step and in essence whether you have the certification or not, your home’s performance will be the same. But for Janice this final step felt like the perfect end point: once you have gone so far, why not go the whole way. It is also good to be able to actually monitor the performance of your house for resale purposes and because it is nice to know that extra effort in construction has been worth it. In this case, Josh was able to use Hazel Tree House as the basis to get his Passivhaus designer qualification as well.
Not everything will go to plan
Janice and Colin encountered their biggest challenge of the build whilst laying the concrete for their foundations. The site access already limited the size of the vehicle that could deliver the concrete and although two trucks had been arranged to deliver the concrete in rely, only one had been sent. To add further insult to injury, when the truck returned, the plant had broken down and they had to go to one further away. When working with concrete, time is of the essence, and the way it is laid can impact the finished outcome. As this concrete slab was also going to be polished and become the floor for the whole of the downstairs, it was even more important that it was done properly and due to the delay, the team stayed late into the night to work on it. This issue did ultimately impact the finish of the floor and there are areas with imperfections, but as Janice points out, these things are quite quickly forgotten about or overlooked once the build is over and you move into the house.
The client experience during the build
Janice lived in a bungalow close to the site during the build so was able to be present on site pretty much every day. She describes this as a great experience as you get to see all of the stages of the process and really feel a part of the journey. She also highlights an interesting flip that you see as the client. For the first half of the build you are watching; because the builders are following the architects plans, you have very few questions you need to answer. But as soon as the internal finishes begin, you start to be asked questions that you haven’t even considered yet. So as a client, the internal structure and design of things such as lights, sockets, stairs, doors, kitchens, bathrooms etc is the area where you will be most in demand.
“You sort of get used to not really having very many questions, or just having a look at things, maybe you’re looking at the windows and stuff. Then suddenly it comes to the internal and ‘Oh, where your stairs going? What stairs do you want? What’s your electric? Where do you want your sockets? Where’s your lights?’ and suddenly, you really are in demand and having to make decisions. You know, really thinking about the internal layout and structure, when you haven’t even got walls necessarily.”
Visiting another house can be an amazing way to understand what you want for your home
All of Hazel Tree House’s internal walls are finished with clay plaster which creates a beautiful and warm textured surface. Janice says that during the planning stage they were able to visit another passivhaus in the area (Old Holloway) who had chosen the clay plaster finish and fell in love with it. Not only does clay plaster create a beautiful effect, it also good for the overall health of the building as it is a natural breathable material which will take in moisture when there is an excess and release it again when needed. The clay plaster can be a good choice too if you are looking to reduce the upkeep needs of a house, as once it is sealed, it is a finished surface that won’t need to be repainted every few years like other wall surfaces.
Being able to see the finish in person really helped them feel confident in their choices and now that the house is completed, Janice and Colin have participated in the Passivhaus open day for visitors who are beginning their journey, to share what they have learnt and help them with those decisions.
“It’s a big part of the finishes getting the clay plastering done. But then it’s done. You know, you don’t have to paint unless you choose to. So basically, once all the plastering is done, that’s it, your house is decorated.”
Adaptability and problem solving is crucial
Having a good builder is very important, as their ability to alter plans and adapt to certain situations is crucial. There were a few occasions where Dai was able to highlight a potential problem and come up with an alternative option or an added precaution that helped to avoid big disasters. One example of this was with the Air Source Heat Pump that was fitted. Because of the size restrictions from planning, Hazel Tree House has what Janice calls a “mini plant room” which is essentially just enough space to fit everything in it. When Dai and his team were constructing the walls Dai pointed out that once the Heat pump was in place it would be very difficult to get out again so he decided to create a removable panel instead of a wall, which would be there in case it broke down. As luck would have it, the heat pump was delivered faulty but this fault was only discovered after it had been installed and turned on for the first time, and Dai had to use his removable panel to get it back out again.
“I think that was the lovely thing about the design process, your builder is solving problems and coming up with solutions all of the time. We have a strange shaped downstairs shower to fit in a very compact space, which caused a bit of headache: how am I going to make a shower tray here because I can’t buy one (unless you want to spend a lot of money). So it’s those things that you’re solving as you go with the help of very, very good builder.”
Open plan living
Hazel Tree House is designed to cater for open plan living and the main social space of the house contains the kitchen, living room and dining room all as one. Janice describes it as a lovely space where you can all feel connected, even if you are doing different things, with also the option for private spaces in the bedrooms and office area.
“It was lovely last Christmas, we had all the family here. You could be cooking and still part of everything that’s going on and that felt exactly what we wanted. Then if you want private space that’s either coming to bedrooms, as a separate space, so we do have a chair in our bedroom. And then an office space that is more functional and actually can be more messy. You can keep the mess out of that sort of central social space and I think it very much functions like that.”
Performance – “You have no concept of what it is like to live in a Passivhaus until you have lived in one”
Janice talks about how she knew that a passivhaus was going to feel very different from a standard house, but was unable to comprehend the realities of that until after they had moved in. The key thing she highlights is that in a standard house, you have warm rooms and cold rooms, so to move within your house you are constantly changing from one to another. In a passivhaus the temperature is constant throughout the whole building, which make the entire house feel more liveable at all times of day and all points in the year. On the day of recording in December the house was 19 degrees centigrade in the morning (after a night which dropped to below 0).
The house has solar panels installed and uses the electricity to heat the hot water tank and power the lights etc. The house only has two towel rails and finds that most of the heat in the house is generated through sunlight, cooking and just generally moving around. The solar panels feed into the grid and are not connected to a battery as this was an expense that the budget couldn’t stretch to, but Janice hopes to get one installed in the future.
“We are very geeky about it because we do constantly monitor the internal and external temperatures, we have monitors all over the place. And you have to learn to manage it as well, I think, because it is so different and so new. It was 19 when we woke up this morning, and it’s gone up to just about 20, just from us being here and having the oven on a bit… What we’re finding is it drops one or two degrees overnight, because it’s not 100% efficient in keeping the temperature in. And then in the evening, when you’re sitting down more, that’s when you might want to have a bit of heating on just to boost that temperature. And we just use, an electric heater and we have the towel rails, but that is all that we’re pretty much using.”
Is it luck or is it having an open mind?
Janice highlights that it was a relatively smooth build, and they didn’t have any major issues. There were things that went wrong, like the concrete plant breaking down when you are in the middle of laying the base slab or the water heater being delivered faulty and having to be replaced straight away. But the overall feeling is that these things are what you make of them. Janice talks about her build with positivity and an overall sense of enjoyment, so whilst it may feel like luck, your own mindset and flexibility is a crucial factor in any project.
“It has gone really, really well and I think knowing we wanted it to be an eco house helped from the start, because then that’s what we were looking for. And to some extent, you can say we were lucky to come across the right people, but I think it was then just trusting your gut about how you got on with someone because that relationship is something that’s going to go on for nine months. I think it’s probably very important, because it’s a process you’re all going through for that length of time.”
Architect Josh Wood gives us an insight into his own self build project, where the balance between keeping costs low and creating a sustainable home have pushed him to come up with creative solutions. By undergoing most of the work themselves, Josh and his partner Amy have been able to transform their snug, back garden plot, into a comfortable and energy-efficient home. Josh explains how thinking outside of the box may be an excellent option if you are looking to get on to the property ladder with a smaller budget.
Interview with Josh Wood
Bristol based architect and founder of Green Trace Architect, Josh Wood joins us today to explore the topic of low cost sustainable homes. Josh is a qualified Passivhaus designer, with a background in environmental engineering and he specialises in sustainable architecture and creative design. Along with his Partner Amy and a handful of friends, Josh has undertaken quite a feat in building his own sustainable home in Bristol on a modest budget. In this chat, Josh talks us through his experience in working with clients, building his own tiny house and now his own self build, highlighting the key lessons that he has learnt along the way.
Join The Hub to access our in-depth video case study of Buckinghamshire Passivhaus, a PH15 build
Tiny houses can help you identify how you want to live
The tiny house revolution is one we have seen grow over the past few years and in this chat Josh talks of his own experience living in a tiny house he built himself. Tiny houses can be a great option when you have a thirst for building but are on a small budget or wish to escape the expensive private rental market. Tiny houses can offer a wonderful starting point to experiment with different design ideas and learn a range of skills whilst working on a small scale. In limiting yourself to live in such a small space, you can analyse just how you want to interact with your home and identify what you maybe took for granted in the past. Josh talks of how the size restriction challenges you to use space incredibly efficiently and pushes you to live a lot of your life outside. This experience helped Josh make connections through the Bristol Tiny House Community and overall he learnt a lot about how he needed his home to perform for him.
See opportunities where others don’t
Many people view small and oddly shaped plots as too difficult to work with, which means they are often dismissed at the beginning of the search for land. Josh explains that to afford this project in the heart of Bristol, he knew they would need to think creatively when looking for a plot. His search mostly consisted of these often overlooked sites and instead of viewing them as restricting, he saw their limitations as the framework of an exciting design challenge. There is a wealth of quirky plots across the country that many people overlook, but it may just be your ticket onto the property ladder if you are willing to think creatively.
“I’d been searching for land and I was always keen on buying a piece of land that everybody else thought was just useless.”
A failed planning application attached to a site is not always a sign to run the other way
When Josh initially found their site, the vendor had applied for planning permission but had failed to get it approved. Normally, these applications are then withdrawn from the planning website, but in this case they were not. This was very fortunate, and Josh took the comments from this failed application as a checklist that he would need to meet in his design. This is another instance where if you are willing to think creatively, what may originally seem like barriers can become guidelines.
A planning pre-app can help reduce the risk
Josh highlights that a pre-application to the planning authority can be an excellent option when considering an unconventional plot as it allows you assess the likelihood of success before you undergo the full planning process. Pre-applications are also closed to the public, so Josh was able to find out if their planning was likely to be approved before they had finalised the sale and without it affecting the price of the land. Pre-apps can also raise anything you may have missed or any concerns that the planning authority might have, so you can be pretty certain that your official application will be passed when the time comes. As a result of undertaking the pre-app process, Josh was able to submit their planning application within 21 days of the land being theirs and were granted planning not long after.
Small sites can dictate the design and construction methods
The site for Josh’s build had been parcelled off from a back garden and is located away from the road via a public alley. The site is therefore classified as a back land development which posed a few challenges for the build in terms of access and did dictate a few of the decisions surrounding construction methods. For example, Josh knew from the start that a prefabricated shell would be out of the question due to their limited access. In addition, the width of the standard timber they chose, based on price and accessibility, for their framing limited their insulation to 200 mil. Furthermore, the placement of the site meant that the design had to consider privacy and how to avoid overlooking or overshadowing the neighbouring properties. As a result, the best way to achieve all these goals was with a roof pitch of 25 degrees and to construct right up against another building, leaving a very small 400mil gap to work with. This gap was just enough space to fit scaffolding with a one plank width, so quite a squeeze when fitting the weather defence and siniat boards. All of these constraints can seem a bit overwhelming at first, but Josh’s overarching message highlights that by changing your mindset to view theses restrictions as exciting challenges, will lead to a unique and interesting design that you may not have thought up without them there.
Being both architect and builder can give you greater understanding of each role
The architect-builder relationship is a very important aspect in any project, and Josh highlights that after experiencing the role of the builder, he is better equipped as an architect to relay his designs and communicate with builders on future projects. He has even found the perfect balance between too much and too little detail on his drawings, as to provide a solid outline without restricting a builders need to potentially improvise on site.
“As an architect, you often have to go to sites and have conversations with builders and have conversations with clients, and to actually experience what both of those go through is invaluable as an architect.”
“I also think the age old question for architects is how much to draw and how much not to draw… if you try and draw too much, you’re likely to get it wrong, a builder sometimes knows best. So I found I would draw this in the exact detail, I’ll come to site and go nah that’s just not going to work, actually. So you need to draw the intention and give an indication of what’s required… but as soon as I start to put too much detail in there, it actually becomes less useful.”
Cost vs sustainability
This project began with the premise that it needed to be both a low cost, energy efficient and sustainable home, but this is often a tricky thing to balance. Josh has managed to keep the cost down by doing the majority of the construction himself, allowing him to spend the budget on good quality materials rather than labour. Also, by choosing to use a simple timber frame that could be sourced from local building merchants, constructing his own insulated raft and choosing wood fibre insulation meant that the design embraced simplicity in order to maintain sustainability. Windows are usually quite an expensive part of a build and Josh opted for triple glazed UPVC windows with a U value of 0.78 as they were a third of the price of composite windows. These windows are a great option if you are looking to get a good performance for a lower price, but Josh does also acknowledge that it was a difficult decision as the materials are not the most ecologically sound. This circles us back to our common theme of embodied carbon vs energy efficiency and especially in builds with a smaller budget it is sometimes necessary to make these compromises.
Some building regulations may be waived if there is enough reasonable evidence
In some instances you may achieve planning permission but be unable to actually build your project due to conflicting building regulations, in Josh’s case, drainage almost posed this issue. Because the site is small and located in an urban setting there were concerns about surface water drainage; where would the rainwater go? After carrying out an assessment, Josh put in a request to have the drain feed into the main sewer like the other buildings surrounding the site. However, with the current state of sewage and water disposal in this country, the council is very unlikely to let any new build drain surface water into the sewer, so his request was denied. Fortunately, after undergoing testing on the sites soil, it became evident that a soakaway would be a possibility and was recommended by planning and their site engineer. This was an interesting situation as the soakaway would actually be too close to the building to pass building regulations, but as the advice from the authorities had suggested this solution, this detail was waived for the project.
When do you need paid help?
Josh and his partner Amy have undertaken the majority of the construction themselves, but there were a few areas where they needed help. Josh enlisted some friends and some paid labour when it came to laying the groundwork and the concrete slab, as well has some additional help whilst assembling the structure and getting the glulam beams in place. Josh did choose to enlist some professional help for the render, as lime render is not commonly used in this country and it is very important to ensure it is done by someone who really knows how to work with the material. With that being said, the rest of the work has been done by Josh and Amy and shows that it is possible to keep costs down by reducing the need for paid labour.
Of course, there are limits to this and sometimes paying for a professional service also gives you peace of mind. Josh explains that he chose to make the insulation raft for the foundations of the house himself rather than opting to use a system like Isoquick but wouldn’t necessarily recommend this. The risk with a foam raft is that if it breaks whilst the concrete slab is being poured, you end up with a big concrete mess. Fortunately, Josh’s stayed intact and he was able to save £5000 by taking on this challenge, but the stress of the process might make him reconsider the decision in the future. Ultimately, it depends on the risks that you are willing to take and the hands on work you want to put into the build, but Josh provides an excellent example of how these creative risks and out of the box solutions can lead to a wonderful home.
What not to compromise on in a low cost build
Building a sustainable and well insulated home were priorities from the beginning, but Josh has ended up improving the spec on a lot of the materials/insulation and included an MVHR system which was not on the original design. This is quite common in these projects because as it progresses you realise you will only undergo this process once and you want to get things to as high a standard and performance level as you can. Things like airtightness and MVHR systems are not ideal areas to compromise on as they are pivotal factors in the overall performance of the house.
“The initial plan was not to have any of that because we thought we wouldn’t have the money. But as we’ve gone on, we actually shoehorned in the MVHR because I thought we can’t not have an airtight home, and if we’ve got an airtight home, we need the MVHR.”
“But with these things, you will keep on working, you’ll get more money, and it will come and then you’ll wish, I wish I put it in. So we’ve kind of gone on that basis.”
How well does the house perform?
After Josh’s calculations using the Passivhaus Planning Package, the house meets the Passivhaus requirements for airtightness, but just slightly falls down on the level of insulation needed to get full passivhaus certification. However, it does meet AECB building standards and has excellent performance, especially considering the limitations that they were faced with. Using sustainable and breathable materials such as the wood fibre insulation also help to maintain the overall health of the structure and will create that overall pleasant environment that Passivhaus is known for.
Internal finishes can be a great place to save money
Josh and Amy are still working on the internal finishes of the house but have already managed to make use of a lot of reclaimed materials. They have created a beautiful balustrade out of old gates and plan to construct their kitchen out of second-hand filing cabinets. Using reclaimed elements, especially in your finishes, not only allows you to save money but also think about materials more creatively and bring some wonderful character to your home. Josh also opted to use a company called Stair Box who provide flat pack staircases. Whilst this was a bit of a puzzle to assemble, it is an interesting solution when trying to work within a low budget.
Slow down and try and enjoy the ride
One of Josh’s pieces of advice was to slow down because things take as long as they take. In trying to rush things, we often make mistakes, do a bad job or end up having to do it all again. It is important to remember to slow down and consider each stage so you can be sure you are doing it the right way, and you might even enjoy the process more too!
“I think I now understand the tale of the hare and the tortoise. Because I never really understood that as a kid, where’s the moral in that? And I think now it makes sense to me as a builder, you’ve really got to plod not run. Architects may be working at such high pace sometimes that can’t be good for either you or the project. I feel that I’ve learned to take things slowly and that’s been actually more beneficial to doing the project efficiently”
Take risks, think creatively, and keep searching for that perfect piece of land!
Overall, Josh’s message is that you can achieve a sustainable and high performing home on a small budget. By seeing potential in the things that others may overlook and taking risks, a self-build project can be an excellent way to get on the housing ladder.
“My advice, I suppose, would be to keep looking for those small bits of land and be very creative about how you might be able to make that into something!”
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.”
Hattie Hartman, Sustainability Editor at the Architects’ Journal, shares insights from her new book Energy, People, Buildings.
Interview with Hattie Hartman
Hattie is an architect and sustainability editor at the Architects’ Journal, but by her own admission didn’t have a conventional route into the profession. She attended university in the 1970s wanting to change the world and thinking that working in politics or studying law was the way to go about it. However, a course on renaissance architectural history, and some inspirational teachers, changed her thinking and set her off on a path into architecture and journalism.
Together with Judit Kimpian and Sofie Pelsmakers, Hattie is co-author of Energy | People | Buildings – Making Sustainable Architecture Work. She also hosts the Climate Champions podcast.
Architecture is fundamentally about people
Hattie admits it is incredibly challenging to design a really good building and says that ultimately it is about understanding how buildings really work, to make them comfortable and good for the people occupying them.
She says that sustainable architecture has typically had a reputation for “doing with less”, but it doesn’t have to be about doing without, rather doing things differently in a lean way. Hedonistic sustainability is one such idea that promotes sustainability which actively improves the quality of life and human enjoyment.
The book is based on the collection of feedback
Judit Kimpian approached Hattie to collaborate with her on their book, Energy | People | Buildings – Making Sustainable Architecture Work, before also inviting Sofie Pelsmakers to work with them. It is a RIBA Publishing book that Hattie says is aimed at design professionals, engineers, students, and people that operate buildings.
Hattie says that Judit knows everything that there is that can and does go wrong with how buildings operate, based on Innovate UK building performance studies that she worked on, and this work formed the basis for the book.
An important takeaway from the book is that feedback isn’t something that you just do at the end. It has to be built into the whole process right from the beginning.
“When you keep track of all the things that are going to impact a building’s performance from the beginning, and you have buy-in, not only from the whole design team and the client, but from the contractor, and the real critical point is you write that into the procurement. You can actually track these things and make sure that buildings perform, and you can troubleshoot, and you can find problems and solve them quickly before they become huge, expensive things to sort out or lawsuits.
Cost of monitoring is not a barrier if planned for from the outset
If left to the end then it can incur additional time and expenditure to find and collate the data, but when it’s been planned from the outset it can be a minute cost in terms of the overall budget for the building. An example Hattie gives is if the energy meters are part of the contractor’s responsibility, then the right meters will be installed and any problems will be sorted out immediately. This scenario is preferable to the alternative which could be the wrong meters being installed, they’re not properly commissioned and you can’t get the right data from them.
Architype are leading the way at making building performance standard practice
Architype has spent several years developing their work processes, training their staff, carrying out research projects, and working with a PhD student to bring the expertise in-house. This investment and dedication mean clients are now approaching them, asking for a building that will perform.
A case study from the book is the Enterprise Centre in East Anglia, which Ben himself has visited and describes being asked for details when signing-in on arrival about how far he had travelled, what vehicle he was driving etc, in order to be added to the data about the carbon footprint of the building. Hattie credits the Enterprise Centre for being a visionary client and explains that none of this is hard, it just needs to be made a priority.
The operational performance gap needs to be reduced
Hattie points to ACAN’s recent report about the role of embodied carbon in buildings as being an excellent resource in explaining what needs to be done to regulate that, which is an important part of getting to net-zero. And she says equally important is the operational performance gap which still needs a lot of improvement. Their book sets out a demystifying process of how to get to grips with the operational emissions of buildings,
Integrated design is crucial
Hattie stresses the importance of getting all the expertise around the table right at the start, before anything has even been sketched, to think about the passive design and the fabric of the building. Even for a small project like a house extension, having that expertise can reduce the embodied carbon by perhaps opting for timber solutions over steel or concrete. That expertise can also be continually revisiting and challenging the design decisions along the way.
Carrowbreck Meadow features in Energy | People | Buildings
You can’t know where you are unless you have targets
The book has a section about targets, and while Hattie agrees that targets will change and perhaps become out of date, it is important to have them and be measuring to get an idea for how you’re doing.
Technology in buildings needs to be tested and understood
There are benefits to keeping things simple and, with added technology, there can be more things to go wrong. For example, Architype used to use lots of actuators on windows, but now try to keep them to a strict minimum. The more that can be done manually the better!
There is a learning curve for everyone!
One of Hattie’s podcast guests is Sarah Wigglesworth, an architect committed to sustainable design for many years and who built her straw bale house 20 years ago. At that time sustainable design was more about a “loose fit” and the building wasn’t designed with airtightness or thermal bridges in mind. When it came to retrofitting she worked with an environmental consultancy and spent many months measuring and collating data to come up with a prioritised checklist of things that they could do to improve the building.
With so many buildings in the country that need retrofitting, it shows that if you don’t measure then you don’t know what the priorities are.
Feedback is important for future improvements
Hattie says that quite often architects don’t want to know how well their buildings are performing (or under-performing!) or indeed make their clients aware because there can be a question of liability. She was pleased however to have case studies in the book where people were willing to share what hadn’t gone to plan and where things could have been done differently. She says this is the only way to be able to make future improvements.
The podcast and book aim to make a technical subject accessible
Hattie hosts the Architects’ Journal’s new Climate Champions Podcast. And while she says she’s pretty sure that it’s mostly people who are already interested in the subject that are listening, she’s hopeful that the influence of people like Greta Thunberg and groups such as Architects Declare and the Architects Climate Action Network are helping to spread the message further and drive a real thirst for change.
Zack Semke explains why he’s passionate about facilitating the communication and flow of information around Passive House.
Interview with Zack Semke
Zack is based in Seattle, where he works in marketing consulting services for the high-performance building industry. He is also a director of Passive House Accelerator: a website that brings together different sources of information to educate, inform, and promote the work that is being done by the Passive House community.
The construction industry has lacked innovation
Compared to other industries, construction has been famously lacking in innovation, but Zack says that Passive House is changing that. By using physics to understand how to design and construct buildings better, Passive House is re-thinking the basics of the skeleton and skin to improve performance.
The learning from new technologies will drive down costs
Zack uses the example of solar energy to show how there has been a massive drop in the cost in recent years.
He attributes this to Wright’s Law and the learning curve effect, which applies to all technologies. It says that for every doubling of units produced, there will be incremental reductions in the costs. This is brought about by the additional learning and micro-innovations that happen across the supply chain. In the case of solar energy, Zack says it looks as though every doubling of solar panels across the world brings about a fall in prices of 30%.
The same principles can be applied to Passive House buildings, so that costs can be driven down to more of a cost parity with conventional construction.
There has also been progress in the components supply chain over recent years, with triple glazed windows for example coming down in price.
And once costs become on a par, it becomes a no-brainer to build Passive House, with all the lower energy and health benefits too.
“That’s why I’m so passionate about facilitating communication and flow of information between practitioners, policymakers, marketers and whoever it is, because we want to accelerate this process as much as we can so that when a project happens in the UK and there are lessons learned from that project, we can see that learning being applied in Seattle for example.”
We know what we’re getting with Passive House!
Zack credits the focus on physics as providing such an important contribution to the sustainability movement. The development of tools like PHPP, which are not too complex or too simplistic to use, mean that there won’t be the performance gap that can be found with other green building standards.
There will be a wave of uptake
Zack is encouraged by the explosion of Passive House that is happening across parts of North America, particularly in Vancouver where enlightened public policy is incentivising Passive House and net zero construction, and New York City where carbon emission restrictions on existing buildings are being imposed, paving the way for huge numbers of deep energy retrofits.
And whereas the Living Building Challenge has been incentivised, it was designed to be exactly what it says – a challenge. Zack says that it doesn’t factor in scalability and is seen as the moon-shot of green building. Passive House on the other hand is set up to be cost optimised.
“As cities become actually serious about delivering on climate goals, they’ll recognise that there is no other green building standard or approach that rivals Passive House on reducing operational carbon emissions.”
He gives the example of affordable multi-family buildings in Pennsylvania. The body that oversees the funding, the Pennsylvania Housing Finance Agency, has prioritised Passive House in their scoring for projects that are looking for funding. It doesn’t cost the state anything to add that as a priority, and the result is that developers know if they include Passive House in their schemes they will be at greater chance of securing funding against competitors. This has seen a wave of Passive House construction of affordable housing in the state.
Pax Futura Passive House apartment building in Seattle. An example of the kind of urban infill, multi-family Passive House building that we will need to see more of in order to address the climate crisis. Image Copyright Cascade Built
Embodied carbon is a challenge we have to address
“Operational carbon is the first thing that we need to tackle in my view, but just like so many things in the climate action space, it’s not an either/or conversation.”
Zack credits the Living Building Challenge for the new zero carbon certification, which is one of the first to consider how to reduce and offset embodied carbon.
He says the Passive House community is embracing embodied carbon as a challenge, and the Passivhaus Institute is dedicating resources to its research and thinking about tools for how it could be addressed. He would be keen to see them including energy-related embodied carbon calculations and looking at the implications of those decisions.
The Passive House Accelerator shares information and innovation
Created just over a year ago, the Passive House Accelerator is an open source global platform, that is partly a place that shares content that others have created about Passive House. They also host virtual weekly presentations by Passive House experts, followed by Q&A sessions on screen.
In addition, they present a podcast, and host roundtable discussions, on a variety of related topics.
Hattie Hartman, Sustainability Editor at the Architects’ Journal, has launched a new podcast with architect George Morgan from One Point Five Architecture.
It aims to share knowledge in an era of climate emergency, speaking to change-makers and innovators who are transforming architecture as we know it by designing in ways that respect planetary boundaries
Tim Martel explains how to model the embodied carbon of your build using PHribbon, a tool that plugs in to PHPP (Passive House Planning Package).
Interview with Tim Martel
Tim is a qualified architectural technologist and Passivhaus designer. He also works for the AECB and is a course tutor for the CarbonLite retrofit course. Helped by a background in programming he has used his research and experience of working on new builds and retrofits to create PHribbon – a tool which enables people to model the embodied carbon on their build.
PHribbon is designed to specifically work with the PHPP software
While there are other specialists who do work on embodied carbon, PHribbon is unique in that it has been designed to work specifically with the Passivhaus Planning Package (PHPP). This is a benefit because around 80% of the information needed is already in PHPP. The additional information needed will be the things that aren’t covered by PHPP, such as internal walls, floors and roof coverings.
PHribbon front screen
The calculation is built around a RICS document
The Royal Institute of Chartered Surveyors (RICS) wrote a document in 2017 called ‘Whole Life Carbon Assessment for the Built Environment.’ It’s a statement of what members have to adhere to and sets out in detail what is expected of the calculation. While the RICS calculation can only be done once a building is complete, Tim is able to use quantities that are in PHPP to give a good estimate of what the embodied CO2 of the building is likely to be.
Information is gathered from Environmental Product Declarations
The RICS calculation uses information from Environmental Product Declarations (EPDs), which are documents that work to European EN standards and which quantifiably demonstrate the environmental performance of a product. RICS also go through the whole lifetime calculation with detail on what should be done at each stage and what assumptions should be used. Assumptions being necessary sometimes for standardisation, because of the inconsistencies of different people coming up with different answers even for the same building. With lots of companies producing these declarations, (Tim now has around 200 in PHPP covering many different materials) the challenge might be in convincing manufacturers of products with lower environmental credentials to share their information.
CO2 results can be shown in different ways
As long as you are able to provide the net internal area (NIA), results can be shown as kilograms of CO2 per metre squared of net internal area. In addition the graph can be customised to show total CO2 for the whole building, kilograms of CO2 per metre squared of TFA (that’s usable space in Passivhaus language), and even CO2 per occupant.
Awareness is drawn to potential inaccuracies
Tim stresses this isn’t an official calculation, but it does closely follow the RICS standard. There will however be some inaccuracies, and these are highlighted by a colour coded system in PHribbon to draw attention. Some EPDs they can be fairly certain about so will be coloured green, but others that they’re less confident of will be orange or red. They might be ones that are based on RICS assumptions like 300km being the assumed transport distance from various manufacturers to the site if its a national product, whereas in reality it’s likely to be more or less than that.
Generally speaking, the information is likely to get more accurate as more EPDs are produced, and with more available it’s highlighting just where the missing information is. In particular, it would be useful to show information for the end of life stage, and include reuse and recycling benefits.
Results can be tailored to show alternatives
With several examples already completed, Tim says his findings show a typical semi-detached house as having around 14 tonnes of CO2 for the whole life of the building, with about 10 tonnes of that just for the materials themselves. The benefit of using PHribbon is that comparisons can be made in a graph by using different options, such as what the figure might be if the house was made out of brick, as opposed to timber.
Example of whole building using timber, PIR versus brickExample showing 100m2 wall using timber, cellulose versus brick
More information is needed about the end of life stage
With some of the more typical timber constructions where I-beams and cellulose are used, both of those have quite a large storage component so a large bar represents that storage which offsets all of the emissions in the RICS calculation.
Tim says there’s a catch with this though, as one of the assumptions is that in order to include storage you have to do a full life calculation. That then uses the RICS assumption that 75% of the timber is incinerated at the end of life stage, with the other 25% going to landfill. Unfortunately there isn’t currently enough information about recycling and reuse to produce those in the EPDs as an alternative.
“If you could say, ‘this building has been built so that it can be taken apart and recycled. This material is ideal for being recycled so it can be made into OSB, MDF or anything’, if that can be done and we can prove the figures for it with an EPD for that process then you could legitimately add that as another option.”
Clare Whitney from Clayworks explains how clay plasters are made, their applications and why we might choose them over other wall finishes.
Interview with Clare Whitney
Clare Whitney has been working at Clayworks since 2009. The founders of Clayworks were specialists in cob building, even writing a book about it, and used clay onsite as a sustainable building product.
Clayworks now manufactures natural clay plaster, having spent two years creating a consistent and tested product that can be ready mixed and made available to anyone in the world at any time.
Clay is an ancient building material
Clay is one of the most naturally abundant minerals. Clare says that clay blocks and clay building methods are being rediscovered all around the world as a sustainable material with relatively low carbon intake. Clayworks focus on the application of clay as a plaster.
Clay plasters finish the interior walls of buildings
Clay plasters are a mixture of clay subsoil, aggregates and some natural form of fibre, with clay acting as the binder. Clay absorbs moisture, so water intake is critical; too much or not enough affects the consistency. Clare explains that Clayworks comprehensively researched different clay minerals to get the mixture absolutely right, so that the clay will not crack or “dust”.
Clay plaster differs from other wall finishes in several ways
Clare says it’s hard to describe the aesthetic, as you really have to see and feel and sense them, adding, “It’s a completely different feeling to walk into a room with clay plasters.”
Advantages of clay plaster include:
A different aesthetic:
• The patina is earthy and very soft
• A slight texture gives depth
• Clay doesn’t set, so you can create patterns and textures
More sustainable than most other wall plasters:
• Clay is a naturally abundant raw material
• It doesn’t have to be quarried
• The processing of clay plasters is minimal
• Apart from transport, there’s relatively little embodied carbon
Numerous health benefits:
• Clay plaster helps regulate the moisture inside a building
• Helps mitigate allergies and asthmas
• Helps offset the effects of formaldehydes and indoor pollutants
The robustness of the material:
• The product is scientifically tested
• Proven finish and durability
• Transportable and widely available
Clay plasters work with any type of construction
Clay plasters are now used all over the world in cities and in steel and modern buildings. However they have typically been used a lot in straw bale constructions and buildings with a lot of timber, due to their moisture-absorbing properties, and also in Passivhaus and other buildings where sustainable building products are key.
Furthermore, clay plaster helps to absorb odours and has very clear acoustic advantages, making it ideal for use in bathrooms and kitchens.
Materials can be beautiful as well as functional
Although their clay plasters were originally marketed on sustainability and health credentials, Clare says designers and architects have adopted them for their aesthetic qualities.
Clayworks’ plasters are now being supplied to customers all over the world; Clare attributes this success to their ease of use and the fact they can be trusted to stay on the walls and hold patterns, sculptures and shapes. Commercially their clay plasters have been used to fit out of well-known chain restaurants and public buildings.
You don’t need to paint clay plasters
Clare makes the point that although their clay plasters are a little more expensive than other wall finishes (starting at around £20 per m2), the overall cost is probably similar because:
You never need to paint them
They are through-pigmented, so you won’t notice a discolouration if they become chipped
They’re easily repaired
Part of Clayworks’ research included coming up with a very comprehensive range of colours using natural mineral pigments. Clare explains, “We make colours in a fairly infinite mix. We’re always making up colours to people’s specifications…we can do a lot of turquoises, blues, greens and we’ve even done pinks and purples over the years.”
Different types of plaster have particular uses
Clay plasters are ideal for internal walls and ceilings throughout a house. The only areas to avoid would be wet rooms and exteriors, where Clare would recommend lime plasters, as they are more water repellent.
Clay plasters can also be used for feature walls and fronts of other surfaces such as kitchen interior bars and similar furniture-type applications.
If you can plaster, you can use clay plaster
Clare says you don’t need specialist skills as clay plasters are applied like any other plaster; it just takes a little longer because the clay is a slightly different consistency.
There is a series of different layers and depending on the substrate, you would need different binders, which Clayworks supply. A base coat and topcoat then follow.
Any good plasterer can use their clay plasters to achieve a plain finish, and artisan plasterers would be able to create specialist textured or sculptural finishes.
Self-builders can learn how to use clay plaster
There are lots of resources and support available:
Call the Clayworks technical team who can talk you through every aspect of how to apply the clay; the services, substrates, primers and the entire plaster build-up.
