Proving a Passive Haus Point
MBC Case Study: Dominic Byrne
For Nottinghamshire couple Dominic and Shamim Byrne, setting yourself the task of proving that a passive haus self build can be completed for less money than it would cost to buy a new home, built by national house builders, was a major undertaking given that for both, this would be a first time project.
Passive haus self build
Shamim is a doctor and Dominic works as a writer on topics such as global energy markets, the environmental impact of climate change and the effects such change will have on industry – so he’s a convert and a huge advocate of “thermal efficiency”.
“We’re still building relatively poor quality, cold homes in this country which consume too much energy to heat. When the chance of a building plot came up I thought here’s a chance to put my money where my mouth is and try and do much better,” says Dominic. Before starting the project, he looked at the per square metre (per sqm) prices of new build houses in the local area from volume housebuilders and based his budget target on them. “I wanted to show that it’s possible to build a higher quality, highly energy efficient home for less and, possibly, much less than the prices of homes sold by volume builders.”
Dominic and Shamim completed their purchase of the plot in the Spring of pandemic-hit 2020. It had a pre-existing planning permission for a chalet bungalow but that wasn’t the house that they wanted to build. “I was already aware of the passivhaus standard but knew that trying to retrofit passivhaus onto an existing design was asking for trouble.”
Having made the decision to strive for a passive build, it became necessary to modify the planning consent that had come with the plot. Dominic explains: “We reorientated the house on the site to slightly enlarge the volume, get more solar gain and we eliminated the previous plan’s six roof dormers to simplify the design and minimise the possibility of cold bridging.”
“Other key areas for the passive standard are the thermal envelope and airtightness. This is where it was really advantageous to work with MBC as their timber frame design delivers well on both of these crucial factors. We also decided to have an ‘upside down’ house – with living, kitchen and dining areas upstairs and bedrooms and bathrooms downstairs.”
Looking around the finished house it is clear why they made the choice to invert the normal layout. The living area has lovely south and west-facing views over the surrounding countryside and across to the spires of nearby Southwell Minster. And, as Dominic points out “warm air rises”. Space heating, when it is needed, comes from an air source heat pump and MBC-installed ground floor underfloor heating with zoning allowing the ground floor bedrooms to be cooler and the hall to be warmer, allowing warm air in the hall to rise up the stairwell to the first floor.
What was project managing the self build like? “It was a learning curve and a challenge but it’s been enjoyable,” says Dominic. “The best service I did myself as project manager was to find good people who could be trusted to deliver great work. MBC have brought their excellent timber frame and passive house expertise and my local builder and tradespeople have brought their superb craftsmanship and skills.
They’ve all be great. I think everyone has felt good to be a part of it. A happy site helps with the inevitable issues that arise from the interface between various trades and timing.”
A key part of that interface was simplified by using MBC Timber Frame for both the foundation solution and the passive timber frame supply. Of course, there was still the groundworks that were needed prior to the foundation works and the considerable number of follow-on contractors that were required after the timber frame went up. In total, around a dozen separate contractors “interfaced” successfully to complete the finished house.
And they weren’t just the normal contractors such as electricians and plumbers. The house has remote controlled electric ‘external’ venetian blinds on the two main south-facing first floor windows to provide privacy and also summer shade. Popular in many other European countries but rare in the UK, Dominic had to search far and wide, in fact as far as Poland, before finding a company with a local UK agent who could supply the equipment.
Shamim liked the idea of a central vacuum system and, although Dominic was sceptical at first, he is now a confirmed fan, demonstrating the power of a kitchen floor clean up with a simple shift of the kitchen unit kickplate panel and in seconds the floor is free of dust and debris.
Dominic and Shamim moved into their new home on 3 November 2021 – a build period of nine months, in line with their expectations at the start of the project. What advice would they offer to those thinking of starting a new build, passive or not? They stress three things:
“Be sure you have the appetite for the inevitable challenges that will lie ahead. The rewards are great but you do need to have the commitment to put a fair amount of effort in.”
“It’s crucial to surround yourself with the right people. Take the time to meet and talk about the project with them and pay attention to your gut instincts if you are worried anyone isn’t a right match to your project.”
“Finally, be sure you have the time you need if you decide to project manage it yourself. To do it properly is pretty much a full time job!”
But did it work? Was Dominic able to build a passive house for him and Shamim to enjoy for less cost than they would have had to pay to buy a new house in the local market?
Their finished project is a 169m2 home plus a separate large double garage and workshop adding another 50sqm. The total build cost worked out at £1,770 per sqm or around £2,000 per sqm for the house alone. Adding in the cost of the plot and professional fees brings the total spend to £2,650 per sqm. That’s 25% to 50% less than the £3,670 to £4,670 range noted down by Dominic for new build houses advertised for sale locally at the start of the project.
Dominic concludes: “The big housebuilders badly need to up their performance. With our self build we didn’t have their economies of scale or buying power. Yet we’ve built a house that is way more energy efficient, has a top end internal specification and has cost us significantly less.”
Some useful info:
Total build cost (house and garage) £386,800
Airtightness: 0.34 ACH
Heating load: 9.8W/m2
Non-renewable primary energy demand: 109 kWh/(m2a)