A prefab approach for a Passivhaus deep retrofit

The Solihull pilot project
The Solihull pilot project

A British company has developed a prefabricated deep retrofit kit that aims to get homes to Passivhaus standard.

The kits involve a wrap-around solution for an existing building that also includes ventilation to ensure good air quality and, because it uses off-site construction, the upgrade process can take as little as three weeks and means occupants do not have to move out during the upgrade.

The company, Beattie Passive Retrofit, has secured patents in 57 countries for its innovative solution, which is called TCosy and been developed with funding from Innovate UK, which channels public financial support to private sector R&D to foster low carbon innovation.

The company’s approach, founded on the stringent and verifiable Passivhaus energy performance standard, also involves using locally trained labour. The Passivhaus standard is hard to achieve because it demands that contractors achieve a high level of airtightness. However, due to the simple system and factory construction, much of the uncertainty is taken out of achieving this. The standard can attain an 85 per cent reduction, or £1000 a year (AU$1846), in heating fuel costs for the average house.

Residents of six flats in a three-storey apartment block owned by Solihull Community Council near Birmingham, England are amongst the first to benefit from the system, following a three-year collaborative R&D project between Encraft, a low-carbon buildings engineering consultancy, Coventry University and a local social enterprise called Jericho Foundation, who trained people facing significant personal or occupational barriers to build the system.

Beattie’s chief executive Ron Beattie, who founded the company in 2008, said: “We have designed the retrofit process to be as simple and efficient for all parties involved. Having tested the processes we’ve proved we can deliver energy savings over the life of a building.”

Gareth Cavill, Beattie Passive’s lead architect, said: “The process begins by producing the architectural drawings in house. The information goes to the factory where the frames are manufactured and then taken to the site where they are erected. We source the windows and doors from one of our supply partners in Europe due to their advanced quality and cost advantages.”

He added that the insulation used within the timber frames consists of expanded polystyrene eco-beads.

Isabel Beattie, head of strategy and development said: “The estimated price for a retrofit is £550 per square metre [AU$1015 a sq m] of floor area including the frame, windows and doors,” she said. “This makes a three-bedroom detached house retrofit typically cost £45,000 [AU$83,070]. Our clients are expected to be social housing providers, developers and self builders.”

Certainty for investors

The approach is similar to that offered by the Investor Confidence Project, in providing a guaranteed rate of return and financial package to investors, the key being the simplicity and certainty guaranteed to the investor and to the housing provider of the whole offer.

Mr Beattie believes this approach will solve a key problem facing deep retrofit agendas – financing their comparatively large upfront cost.

“Once we can guarantee energy savings, we believe that pension funds and other long-term investors will be prepared to lend over 30 years, with a return after that. And we will have pulled people out of fuel poverty,” he said.

“We showed estate agents in Birmingham what we’re doing and their studies suggest a £65,000 [AU$119,990] uplift in value on a £120,000 [AU$221,519] property, because you are putting a new building over the top of the old one. If redecorated, with a new kitchen and bathroom, you’re looking at a completely new house.”

This raises the possibility of generating a profit from deep retrofitting.

Ms Beattie said the company was already talking to pension funds about investing in retrofits for future roll-out at scale.

“We estimate that savings generated by the retrofit of on average 85 per cent of heating requirements would help pay back the investment within 30 years,” she said.

“With this type of program the tenants generally pay one fee that includes rent and energy, and it is from this income that the housing provider would pay back the investor. The fee would be reduced slightly for the tenant compared to the non-retrofitted rent, and they will also have a warmer, healthier home.”

Mr Beattie said the company was in growth mode, with the appointment of new sales staff and an architect.

“Work is coming in and growth is going to be very fast,” he said. “We are due to start manufacturing in the factory soon and we’ve got seven or eight homes booked in, ready to go. They range from private client, multi-million pound houses to standard affordable homes for Hertfordshire Council – different ends of the market, but the same process.”

To fill the demand the company will soon open a factory on the Scottow Enterprise Park, formerly RAF Coltishall. With 57 patents secured abroad, it is clearly confident that expansion on a large scale is possible once small proofs of concept are installed. With 20 million homes in the UK alone needing a low-energy retrofit, the market is clearly huge.

David Thorpe is the author of:

More Articles on this Topic