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  • HPH362: An easier way to build a certified Passivhaus – with Clare and Ross Booth

    HPH362: An easier way to build a certified Passivhaus – with Clare and Ross Booth

    Clare and Ross Booth from Coldwells Build share details of their prefabricated, turnkey Passivhaus designs that aim to simplify the delivery of high performance homes in Scotland.

    Interview with Clare and Ross Booth

    Ross and Clare Booth are the founders and directors of Coldwells Build in Aberdeenshire, Scotland. Ross started out as a joiner and construction worker while Clare has a background in journalism and communication. Their construction company has delivered a number of bespoke housing projects and is now launching a range of contemporary, turnkey Passivhaus designs which will be sold at a fixed price and prefabricated off site.

    This episode is set against a backdrop of potential change to the building regulations in Scotland.

    Help keep the Scottish Passivhaus equivalent on track

    Last year the Scottish Government announced plans to introduce new regulations for all new build housing to meet a ‘Scottish equivalent to the Passivhaus standard’.

    Whilst this was exciting, the devil is in the detail and this is currently being fleshed out in a consultation about the proposal. Unfortunately there are signs that it may be watered down, which means we need to have our say and get it back on track. So please take the time to respond. The Passivhaus Trust has made it easy to understand what detail is lacking, so check out their guidance to help you play your part in the consultation.

    The ‘Passivhaus equivalent’ doesn’t need to reinvent the wheel

    The Passivhaus standard works so well because it is a holistic approach which addresses building physics, and there are quality assurance processes built in so that we get the results we anticipate.

    Clare says that adopting the Scottish equivalent to the Passivhaus standard could have a profound effect on future homes across Scotland, and help the Government reach its net zero emissions target set for 2045.

    Upskilling the workforce is essential

    Clare and Ross believe that for Scotland to achieve higher building standards there is a great need to provide additional training for construction workers. Ross shares an example from his own experience as a joiner when he installed an airtightness membrane but didn’t really understand what it was doing or the attention to detail required when carrying out this work.

    Clare and Ross have both upskilled as part of their professional development

    While networking Clare discovered that some free Passivhaus tradesperson training was available and sent the whole team to Glasgow to attend. Ross admits that he was sceptical at first but was completely converted by the end of the training. This was Government funded and provided by BEST (Built Environment Smarter Transformation) who are working to decarbonise the built environment through upskilling and educating people in the construction industry.

    Clare also attended a number of satellite events at the COP26 global climate change summit in 2021. Amongst her findings was that most homes still rely on oil and gas for heating which is contributing to nearly a fifth of the UK’s carbon emissions, the UK has some of the worst insulated housing stock across Europe, and that the performance gap currently sits at a staggering 60% in some cases.

    A ‘bespoke’ home project is not a simple process

    Having worked with numerous clients on one-off bespoke projects, Clare and Ross have identified key pain-points in the self build journey. For example, it can be difficult to design projects within budget and so clients need to go back and forth between their designer and the construction team until they have refined plans. There’s also fatigue from the estimated 3000 decisions that are needed to realise a new home. Then add in the unpredictability of the build itself, which may be subject to bad weather delays and noise complaints from neighbours.

    Building off-site in a workshop is a lot more predictable

    In an attempt to address some of the challenges of self build and streamline the process for their clients Clare and Ross decided to create a collection of predesigned homes that they would sell for a fixed price. Not only would these be beautiful contemporary homes but there would be a set number of materials and colour choices, making it easier for clients to choose. Another big change would be taking advantage of modern methods of construction by prefabricating these houses off site in a workshop. This also has the potential to increase quality as everyone can be trained in specific roles.

    By increasing the insulation specification, their Passivhaus designs can work anywhere in Scotland

    Over the last two and a half years Ross and Clare have been working with John Gilbert Architects to produce six ready-to-go Passivhaus designs.

    As Passivhaus is site specific one challenge they faced was how a standard design could work on any site. The solution was to over-egg the insulation slightly so that the solar gains were not as critical.

    We’ve got quite a chunky wall and roof system. And we’ve tested the house on PHPP on a coastal exposed site in the North East of Scotland, and we’ve tried it in every orientation, and it’s passed.

    A visualisation of one of the ready-to-go Passivhaus designs

    A building plot is essential to start the process

    Although you might be tempted by the designs you need to have secured a building plot before you can engage with Coldwells Build. After selecting a house design they will check that it works for your budget, before moving on to a concept agreement.

    At this point it is possible to make a few internal layout changes, providing that they don’t lead to structural changes. The team will then prepare a site plan and get everything cost checked and prepared for planning permission.

    Once planning has been approved, Coldwells Build will create a preliminary building agreement and you can start looking at the internal finishes and kitchen designs. They will get the cost as accurate as possible at this stage and then the architect will submit for a building warrant. Once this has been approved, the client can sign a building contract, and the prefabrication will begin.

    Assembly ‘on site’ will take a matter of days

    Ross says that prefabricating the home would start within three months of having a building contract signed. Whilst the prefabrication is happening, the groundworks team can be on site, preparing the foundations, substructure and floor slab. Once the timber frame is delivered to site, it can be made wind, water and airtight within days. The cladding will be pre-installed and the wall panels and roof panels pre-insulated. The airtightness membranes will be pre-fitted, and only the joints will need to be taped on site. It is a quick turnaround from arriving on site.

    The costs will be fixed and known upfront

    Clare says that the average price for their four-bedroom turnkey design will be around £420,000. There is also a ‘You Build’ option, which gives you a completed shell that you would then have to fit out, and this is currently around £220,000. Again this is for a certified Passivhaus, which is core to their offering.

    The Passivhaus collection will be launched next month but there is already a lot of interest and they even have a waiting list! So it’s an exciting time for Coldwells Build. They are currently working with their first customer which they will use as a test run and to check all their processes, before taking on more customers. Initially they are going to be limiting themselves to producing six houses per year. Clare explains that the most important thing is not to overload themselves and therefore ensure the quality of their homes.

    Find out more

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  • HPH351: Creating affordable, high quality, low carbon homes – with Linda Farrow

    HPH351: Creating affordable, high quality, low carbon homes – with Linda Farrow

    Linda Farrow from Agile Homes explains how their prefabricated panelised system can deliver high quality and truly affordable homes that are good for the planet.

    Interview with Linda Farrow

    Linda Farrow and her partner Craig White set up Agile Homes in 2019 to address the need for better housing in the UK. They aim to deliver low-cost homes without sacrificing on quality, and each of their buildings is low carbon, energy efficient and has the ability to be disassembled easily (at the end of its life cycle).

    Timber panels with straw in-fill are made off site

    Linda explains that at the core of an Agile Home is their Modern Methods of Construction (MMC) panelised system. These panels are prefabricated in a factory and then assembled quickly on site, giving you a watertight structure within a day or two. The use of natural materials like timber and straw ensures that the homes have an extremely low embodied carbon and the panelised nature of the system mean it can be easily customised to meet the client’s needs. This makes it incredibly versatile and can be used for a variety of projects, from a block of flats to a one bedroom bungalow.

    Their housing model aims to overcome common challenges

    Linda explains that as part of their mission to make good quality and affordable housing accessible in the UK, they needed to identify the current barriers in the construction industry and come up with creative solutions to overcome them.

    There is a cultural wariness of adopting renewable materials

    England has a romance with brick and block construction that is proving tricky to shift. Even our children’s stories have perpetuated this message by telling us that a house made out of brick will be sturdy whereas a house built from straw and sticks will leave us vulnerable to attack.

    This cultural mindset shift will take time to change but as more projects are completed it will keep demonstrating how well natural materials can work.

    There is a lack of affordable land to develop

    The price of land is currently a major barrier for affordable housing projects and often takes up a large proportion of the budget.

    By collaborating with councils, housing associations and charities, Agile Homes works to unlock land at low or no cost for social value. This can quickly reduce the delivery cost by around a third.

    It needs to be easier to finance and insure sustainable projects

    It can still be a challenge to finance or insure ecological projects because they are deemed higher risk.

    So Agile Homes has invested time in developing relationships with companies such as the Ecology Building Society and they are now an approved supplier.

    They also gained BOPAS (Build Off-site Property Assurance Scheme) accreditation which is recognised by mortgage lenders as providing the necessary assurance that properties that use modern methods of construction (MMC) will be readily mortgageable for a minimum of 60 years.

    Gaining planning consent is not always straightforward

    Getting planning permission for a project can be quite involved and take time, which is why Agile Homes have developed a modular solution called TAM which complies with the Caravan Act. This generally means planning permission will not be required because they are moveable rather than permanent structures.

    TAM (Transportable Accommodation Module) is a rapid response housing solution

    TAM is a prefabricated, rapid-response housing solution.

    The modules can be transported ‘flatpack’ to site and assembled quickly, leaving you with a watertight shell in a day or two and operational within a few weeks. Depending on the site and the needs of the client, TAM can also be umbilical to an existing building, using the same power, water and drainage systems without the need for planning permission.

    “We’re not quite there yet, but one of our aims is to make it as easy for individuals and community led organisations to buy into our system as if they were going to a car showroom, and they can sign the finance agreement and drive away in their car. So in the same vein, they could sign a finance agreement and have their TAM delivered to their site”

    Delivering a ‘turnkey’ solution helps to maintain quality

    The larger the development the more likely it is that different companies and sub-contractors will be delivering different aspects. Inevitably this can lead to mistakes or inconsistencies. So at Agile Homes, where possible, they like to control the whole process.

    “In essence it’s about control, and making sure that we can deliver the quality of product to the client. If you use a conventional procurement method where you’ve got the design and then you transfer over to a main contractor, the main contractor is incentivised to find all manner of ways to reduce their costs and increase their margin. And that’s not a criticism, that’s just the way the system is set up. We are a values led organisation and our board scrutinises everything that we do carefully. So I think it is about aligning everything that we do with our core value of respect for people and planet. It’s about control throughout the process to make sure that we can deliver to that time after time for our clients.”

    LILAC in Leeds

    Prefabrication can take place at a ‘pop-up’ factory

    The panelised system has been designed so that it can be put together with high end power tools. In certain circumstances – such as at the request of a community led project – they can bring the manufacturing closer to site and create a pop-up factory in empty barns or industrial units. This has the added benefit of upskilling communities who are interested in sustainable building.

    The Agile team

    The best collaborators have respect for people and planet

    “The ideal client would be someone whose values align with ours, so respect for people and planet, someone who has access to substantial amounts of patient capital, who is like us, genuinely interested in providing as many people as possible with homes that are affordable in perpetuity. Because having an affordable home, a safe civil space to be in is the foundation stone, in our view, for sustainable regenerative communities. And climate change is quite rapidly going to be a question of water and food crisis. So there are many, many immense challenges on the horizon for society. We want someone who, like us is very focused on helping society to put in place the foundation stone for us to then have the capacity to deal constructively with all the challenges that are yet to come.”

    Inter-governmental policy is needed to be able to deliver widespread affordable housing

    Linda explains that the biggest challenge for Agile Homes is access to patient capital and limitations caused by a lack of inter-governmental collaboration on housing policy.

    “Governments have a duty in between terms and outside of party political allegiances to look after human beings and the planet. There are some policies that should be negotiated and agreed as being inter governmental.”

    The natural materials contribute to a calm environment

    Agile Homes has carried out work for local authorities, housing associations and charities, and quite a lot of their residents are vulnerable. This can range from physical disabilities, mental health issues to learning disabilities. So some key feedback they have received is that the natural materials and quality design have created a calm atmosphere which can be of great comfort to anyone but particularly to those with special needs or mental health challenges.

    Agile Homes are committed to sustainability from their build system to their business model

    Linda explains that Agile Homes aims to create a business model for affordable housing by looking at a wide range of resources which promote sustainability and social value:

    The Agile Homes team is also in the process of finalising their Carbon and Social Value Tokens, which will allow people to offset their carbon emissions in local, sustainable, social developments.

    “We’ve been thinking a lot about how to we evidence and generate revenue from the carbon storage that we’re achieving in our buildings and also in the social value that we’re creating. So we’ve been doing work behind the scenes to build calculators and we’re just about to go live with what we call carbon and social value tokens that can potentially be traded. What that means is that we have found clients who are interested in actually buying and paying for the stored carbon and the generated social value as part of their ESG governance systems and processes. So rather than offsetting their carbon footprint by paying for X 1000 trees, in a plantation 1000s of miles away, they’re choosing to buy the carbon that we can evidence is being stored for a minimum 60 year design life in our buildings and I think that’s very exciting. We have plans to use that methodology to generate revenue that can then further reduce the costs of some of our schemes for our most vulnerable clients. We’re really excited about that extension to the model and that rethinking of how do we generate value and revenue in a truly regenerative economy?”

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  • How Bespoke Can a Factory-Built Passivhaus Be?

    How Bespoke Can a Factory-Built Passivhaus Be?

    Building houses in factories is nothing new in mainland Europe yet in the UK the practice is still uncommon. Perhaps there is a stigma attached to what we envisage a factory build to be, but what is the reality of commissioning a custom built energy-efficient home? In this case study Tony Hills shares his experience of using Hanse Haus.

     

    After being inspired by an episode of Grand Designs that featured a system-built house, Tony and Jean Hills knew that they wanted to go down this route and so started researching turnkey solutions.

    Tony-and-Jean

    For Tony, a biology teacher from Sheffield, energy efficiency was a priority: “What terrifies us is the running costs, the heating costs of your future home because the one thing that will not go up at the same speed as heating costs is pensions and we did not want to be in a position where we had a fabulous building but we’re having to choose between eating or heating.”

    From the outset they wanted to go for the best that they could afford and deemed this to be a Passivhaus. Certification was also important as Tony explains: “If we move out of our home and sell it on we have a certificate that proves to anyone the thing they can’t see. They can’t see the insulation. They can’t see the airtightness.”

    A Passivhaus also uses mechanical ventilation with heat recovery to extract stale air from the house and bring in fresh air, without losing the heat. This leads to a much more stable environment and higher levels of comfort.

    Tony attended numerous exhibitions to weigh up the options and eventually chose German firm Hanse Haus for the build because of their reputation, transparency and belief in their products. Hanse Haus’ Sales Director for UK & Ireland Bruno Kleinheinz is a scientist and engineer rather than a traditional salesman, and Tony respected this approach of just providing information and answering questions, in the knowledge that their houses will sell themselves. And it worked!

    Founded in 1929, Hanse Haus have now built over 30,000 houses and although the architecture and style of their houses vary, each house has a focus on energy efficiency and comfort.

    Tony and Jean bought a plot in Inverness as they were looking to relocate anyway to be closer to their son. This serviced plot formed part of 24 self-build homes, every one of which was unique. The design brief from the council had quite a few restrictions and specified aspects like the colour of the render, the need to have corner stones, grey tiles, black PVC downpipes, and so on. It was also facing north, which was not ideal for solar gains. However, it had a glorious view and so they knew this was the spot.

    Scottish-PH-Foundations

    A Scottish firm laid the insulated concrete slab

    It might seem counterintuitive that you will get a bespoke home when it is factory-built but that is exactly what happens. The process still involves a local architect for the design work, much as would happen on any project. The only difference being that it makes a lot more sense for the architect to know how Hanse Haus’ pre-manufactured system works. This means they can optimise their designs and it becomes less expensive for the client. For example, using the standard-sized windows instead of making them 1cm bigger would make it cheaper in production. However, if you’re willing to pay for it you can have what you want!

    For this project, Tony and Jean used an architect that Christian Wittke from Hanse Haus had worked with previously and who understood the system. The final design was a bungalow with a split level roof. It would have a low metal sloping roof on the south side, allowing for a row of windows above it to bring solar gains into the north facing rooms.

    factory-build-for-tony

    Tony even took a trip out to the factory in Germany to see where his house was going to be built. As you might expect the whole process runs like clockwork: “Trucks bring it across with all the outside windows in, doors, ducting, cabling, water pipes already in, sockets pre-drilled in position. The computer even tells them which order to load everything onto which truck. As the first truck arrives, it’s got the right bits in the right order.”

    The structure was weather proof in two days and then all the work was completed within 12 weeks!

    modules-going-in

    Tony says: “The whole thing was planned so well. Everything is delivered at the right time. It’s as stress-free as you can get a build.”

    tony-hill-completed-house

    Tony and Jean moved in at the beginning of 2013 and are estimating that their heating bill for the year will be £140.

    It seems that their custom build experience was a very positive one.

    They even have a positive planning story – we don’t hear these too often so let’s enjoy it!

    “The planning department in Inverness was so keen when they heard someone wanted to build a Passivhaus in Inverness they got us through planning in an almost record-breaking time. They gave us the warrants very quickly. Our building did not fit their design brief, because there were good reasons why things have to be different, and they accepted that without any problem at all.”