Sustainable design
With this sizeable self build, Richard Spencer has realised his ambition of creating a Passivhaus home for his family
After six fruitless months of house hunting, Richard and Katie Spencer had almost given up. It was at this point that they discovered a three-bedroom detached 1950s home with a large garden in the sought-after Roundhay area of Leeds. “I’d been interested in low energy buildings for a long time and had been looking for something to extend and retrofit,” says Richard. “As the main facade was south-facing, this dwelling lent itself to a conversion that harnessed energy from the sun.”
However, it quickly became apparent that the 105m2 abode was too narrow to achieve the Spencers’ desired layout and that knocking it down and rebuilding would be a better option. “It had single glazed aluminium windows with thin glass, uninsulated cavity walls and an ancient boiler. It wasn’t really worth preserving,” says
Richard. “Creating a new home from scratch would give us much more certainty regarding the energy performance.”
Forming a strategy
Katie and Richard settled on self building a new home, with the backup option of a substantial retrofit if planning permission wasn’t granted. With three other potential buyers interested in the property, the Spencers decided to put in an offer of £426,624 – significantly more than the £399,000 guide price – via a sealed bid. “Even though it was going to be a long-term home, we didn’t want to end up too far under water,” says Richard. “Luckily our bid was successful. ere was less than £1,000 between us and the next offer.”
After buying the property in June 2015, many months of research were needed, given Richard hadn’t expected to go down the self build route. e couple and their daughters, Eliza, 10, and Bridget, seven, were in the lucky position of being able to stay in their fourbedroom 1930s semi in nearby Moortown, as relatives had lent them the money to buy this new property. ey intended to fund the project by selling another house they owned in Hull, cashing in some shares and remortgaging their existing home.
Richard, a former chemical engineer, was on a career break and retraining to become a building services engineer and sustainability specialist. He conveniently had a qualification in retrofitting and was working towards another in Passivhaus. As a result, he already had the required planning software and approached Buckrose Ecological Architects in York with fully formed ideas for the new contemporary dwelling that he and Katie were keen to create.
Developing the design
Although the house is positioned just outside a conservation area, the neighbouring properties are a mish mash of styles including brick, stone and render. is freed up Richard to experiment with the design. “We considered half brick, half render to match some of the other homes on the street but realised it wouldn’t look right with the windows we needed for a low energy home,” he says.
In the end, Richard chose a contemporary rendered aesthetic with timber-clad sections on the elevations, opting for a masonry construction method to tap into the local skill base. “If we’d used the same finish for the whole house it would have looked very bland, but the wood covering breaks it up,” he says. “After watching how the sun moves across the site, I chose a rustic-style product with a deep relief that looks different throughout the day.”
A pre-application meeting with the local authority’s planning and conservation officers reassured Richard that his vision seemed feasible. “e concerns raised about not having too many windows on the long facade facing the road were expected. We didn’t want many units on that north side from an energy point of view, and the best vistas were to the south anyway,” says Richard.
Inside, the house would include an open-plan kitchen-diner and living room, utility, music room and office, with a central staircase leading to four bedrooms, a bathroom and ensuite on the first floor.
A key component was the warm roof, which has insulation within the slope of the structure. “I wanted to maximise that space,” says Richard. “We opted for mezzanine sleeping platforms in the children’s bedrooms, which have doors leading to eaves storage. Plus, there’s another storage platform above the master bedroom.”
e original plans were passed within the statutory 13 weeks for complex projects so Richard could get in and compile a shortlist of building contractors. Only two were willing to tender for the job and
It was very satisfying to have a direct measure of how good the fabric of the building is
their quotes were too high. Eventually, he persuaded K&P Horton Builders to provide a quote, even though they hadn’t constructed a full Passivhaus before. “ey had experience developing low energy houses and I could support them on the design side, so I was confident they’d be able to do it,” he says.
Getting started
In June 2016 the existing property was demolished and the utilities disconnected. is meant setting up a temporary electricity supply in a shed for the trades and moving the water meter to a connection by the road. It was six months before the build commenced though, as Richard was still pursuing his third quote. One early challenge was a poplar tree 9m from the house. e structural engineer feared that this might require an extra 2.5m depth to be added to the foundations to avoid any risk to the property. “Luckily, they only went down an additional 300mm before hitting solid rock, so we didn’t need to go deeper,” says Richard.
At the start of the build, Richard decided to take over from the architect as project manager since he could be on site every day and it would simplify the chain of communication. “It was a big risk and there were various points at which the main contractor wasn’t comfortable with me doing it,” he says. “At one point I even spoke to another designer about taking over, but unfortunately they weren’t willing to pick up someone else’s plans.”
Although he’d learned a lot from visiting eco shows and swapping notes with friends who’d completed a Passivhaus retrofit, additional research into materials was needed. “I spent a lot of time on the phone to various technical support lines for manufacturers,” he says.
One of the challenges was making the mezzanines work, which are up in the bedroom’s vaulted ceilings. “Above the master bedroom, the span was too large for timbers, so we needed to put in 300mm Versalam beams to hang the 150mm joists from,” says Richard. “e stairs up to these spaces in the children’s rooms had be re orientated as there wasn’t enough room overhead. It was more expensive than I thought, due to the glass balustrades around the stair heads.”
Energy focus
A lot of time was spent ensuring high thermal standards were met, with 300-350mm insulation installed in the walls, roof and floor. Careful detailing was required to achieve an airtightness level of 0.45 air changes per hour. “It was very satisfying to have a direct measure of how good the fabric of the building is,” says Richard. Basalt fibre wall ties, timber I-beams in the roof and aircrete blocks between the
floor slab and the bottom of the insulation all help to retain heat, too. When it came to the heating system, Richard opted for a thermal store instead of a conventional hot water cylinder. is is powered by a Vaillant ecotec boiler. Water from the store is then pumped around the radiators or through a plate heat exchanger to heat the supply for the taps instantaneously. Richard also specified a Paul Novus 300 mechanical ventilation and heat recovery (MVHR) system with rigid Lindab ducting. “It’s one of the most efficient units around at the moment, plus it’s quiet to run and straightforward to install,” he says. “It helps to maintain the house at a comfortable and constant temperature of 20°C throughout the colder months.”
Although the building isn’t Passivhaus certified yet, it is expected to meet the standard easily. “It’s performing far better than our previous house,” says Richard. “Our first year’s bills are around
£50 per month for electricity and £32 for gas. is should get lower, as construction wasn’t complete for the first two months we lived here and the MVHR was only commissioned in June 2018. I’m also pleased with our water bills, which are £33 per month – around half of what Yorkshire Water would expect for a house this size.”
Final stages
In April 2018, the family moved in – even though the second fix and decorating weren’t quite finished. Richard started his new job as a building services engineer for Leda the following week and the family’s previous home was sold seven months later. ere are still some finishing touches to complete, including landscaping. e
Spencers also plan to add a Lindum wildflower mat to the garage roof and a sedum layer on the porch roof. For this reason, the building is yet to be signed off by the planners and building control.
If he were to self build again, Richard says he would rather use one company for the mechanical and electrical design to ensure the systems had a joined up thinking. “I got advice on plumbing and heating from the company I now work for, which worked well. However, the electrical side of things didn’t come together quite as successfully,” he says. “For example, we have data sockets without a power socket next to them, which needs rectifying.”
Despite going over budget by £150,000, the couple are delighted with the finish and hope to live here until they retire. “Looking back, the figure we initially intended to spend wasn’t achievable,” he says. To compensate for the overspend, Richard fitted the kitchen himself, completed the airtightness work and put together the energy model updates. “It’s rewarding to have something unique,” he says. “e kitchen island works brilliantly, as the children can be at the table doing homework while we’re cooking. Having the TV and musical instruments in a separate room works well, too. I’ve learnt so much from the build and have even gained a new career in the process.”