Passivehaus plays an active role in saving money on energy bills
This new build near Huddersfield could be Britain’s most energy efficient house. Sharon Dale reports.
AFTER shivering our way through the coldest winter in years, it’s hard to imagine how you could keep a home warm with just one radiator.
But that’s all Geoff and Kate Tunstall have in their new threebed detached... and they may never need to turn it on.
The couple have just built what may be the most energy efficient house in Britain.
Their annual heating bill is predicted to be just £75 a year, thanks to a pioneering build that combines British materials and construction techniques with German technology.
The property, in Denby Dale, near Huddersfield, took ten months to build and is the first Anglicised version of the Passivhaus.
Instead of complicated design and expensive bolt-on energy generators like wind turbines and ground source heat pumps, the Passivhaus creates a simple “tea cosy” effect to keep heat in.
It relies on clever design, orientation towards the sun, careful construction and insulation three-and-a halftimes greater than required by Government building regulations.
No draughts can get in and no heat can leak out of the building, but the air is never stale, thanks to a mechanical heat recovery ventilation system that brings in fresh air from outside, warming it using 99 per cent of the heat from the outgoing air.
The Green Building Company in Huddersfield suggested the design and built the house with the help of a German computer software package to ensure almost complete air tightness and energy efficiency.
Project manager Bill Butcher says: “You can buy a prepackaged Passivhaus from Germany, but the materials are completely different.
“They use solid wall panels and stick polystyrene insulation on the outside of the house.
“They don’t fit into the local streetscape here, builders here aren’t familiar with them and planning can be an issue.
“This Passivhaus is the first to be built using British construction methods with blockwork, a cavity wall and stone cladding.
“We use the Passivhaus methodology but we have built in the English vernacular, which is a first. You can vary the design as long as you adhere to the principles.”
He adds: “What’s important is detailing beforehand and quality control on site. Everything has to be monitored from beginning to end to make sure there are no gaps, no leakage or draughts.”
The three-bedroom property has been built in the garden of the Tunstalls’ Victorian cottage and cost about £150,000
A Passivhaus costs about 20 per cent more to construct than an average new-build but the Tunstalls will enjoy a 90 per cent reduction in their fuel bills.
Warmth generated from the sun through windows, body heat and cooking is usually all that is needed to heat a Passivhaus and the Tunstalls have a solar panel to heat their water.
“There are 15,000 Passivhauses in Germany and Austria and we went to look at one after Green Building Company recommended it.
“We were so impressed. They are ordinary, modest homes, nothing flash. It was minus two degrees outside but the house we visited was warm and healthy and comfortable to live in,” says Mr Tunstall, a retired art and design teacher
The idea is to maximise heat gain and minimise heat loss, so the Yorkshire Passivhaus is highly insulated and has triple glazing with large windows on its south facing front and small ones at the cold, north-facing rear of the property.
Any gaps are minimised during construction and insulation has to be continuous. Any areas liable to settlement cracks are sealed with special air tightness tape to prevent cold air seeping in. “The attention to detail is incredible,” says Geoff.
“We haven’t got plug sockets on the outside walls and we have no lights in the ceiling and that’s so the envelope and insulation barrier isn’t punctured.”
He adds: “Fresh air isn’t a problem because of the ventilation unit and you can still open a window. The only issue can be a dry atmosphere, which
They are ordinary, modest houses. It was minus two outside but the house was warm.
is why we used clay plaster on one wall in every room. This absorbs moisture and then releases it.”
Bizarrely, the house won’t score top marks on the Government’s Code for Sustainable Homes register because points are awarded for renewables like solar panels and woodchip boilers. But it is being closely monitored by the construction industry. Both Mr and Mrs Tunstall and the Green Building Company are hoping that the Yorkshire Passivhaus will provide a blueprint for the future of green housebuilding in Britain.
Bill Butcher says: "At the moment the Government places too much emphasis on microgeneration, whereas Passivhaus standards focus on the fabric of the building. If you can reduce your energy use to just 10 per cent of the norm, then you don't need eco bling.”
He adds: “We’d welcome the chance to build another Passivhaus using our in-house team and we are already passing on the knowledge we have gained with this project. It’s something we think the volume developers are going to have to take notice of.
“The main issue is changing the building culture. We need to put more care into it and make sure we don’t sacrifice quality for short-term profit. We need to have round table scenarios where architects, clients and builders have a stake in the project, rather than putting out six tenders and using sub contractors.”
He would also like to see Government incentives like those offered in Belgium, where Passivhaus owners get a reduction in income tax and in Austria, where they get grants of 15 per cent of the build cost.
The Tunstalls meanwhile are preparing to settle in and road test the new model.
“This winter will be the main test, but we’re confident it will be warm enough. If it’s not we’ll have to have a party. Every person generate a kilowatt of heat,” says Geoff.
For more information on the Denby Dale Passivhaus call Green Building Company, part of the Green Building Store, on 01484 461705 or go to: www. greenbuildingstore.co.uk/denby dalehouse
BUILT-IN SAVINGS: The Passivhaus captures and retains heat from the sun for high energy efficiency. Geoff and Kate Tunstall could have a heating bill of just £75 per year.