Focusing on improving the fabric of houses – the aim of the UK Timber Frame Association’s Fabric First campaign – is a no-brainer for timber frame manufacturers.
“It defies logic to provide a poorly insulated structure that’s not airtight and has significant thermal bridges and then compensate with renewables. You start with the fabric,” said Dr Paul Newman, technical director of Kingspan Potton.
Timber frame manufacturers can generally meet level 3 of the Code for Sustainable Homes relying solely on the building’s fabric and when it comes to the higher levels, timber’s inherent acoustic and thermal properties give it a headstart.
“Timber frame is not a magic bullet,” said Dr Newman, “but it does make life easier.”
Level 4 requires 44% improvement on Part L of the Building Regulations but with “relatively low levels of renewables”, it’s straight forward for timber frame, he said.
Everyone in the timber frame industry is working hard to achieve high levels of fabric performance, Dr Newman added. “The rate of change is something I suspect the industry has never seen. Now is the time for the timber frame industry to make the investment and grab market share.”
Pilot project
Oregon Timber Frame recently developed its product in a pilot project with Yorkshire social housing contractor Southdale Ltd. Through increasing fabric performance, reducing thermal bridging and improving airtightness it produced a pair of semi-detached and one detached house to Code level 3 with no renewables, and levels 4 and 5. “Open, insulated and closed panel construction was used, along with a progressive use of mechanical ventilation heat recovery, solar thermal and PV panels.
The AIMC4 consortium is taking it one large step further with a three-year, £6.4m research project to develop a level 4 house without renewables – for the price of a level 3. The consortium comprises Stewart Milne, Barrett Homes, Crest Nicholson, H&H Celcon, Oxford Brookes University and the BRE.
Stewart Milne’s group product development director Stewart Dalgarno said the project was looking at floors, walls and roofs with a U-value of 0.1, insulation, very low levels of thermal bridging, insulation and enhanced airtightness. Some of this may be achieved through new technologies such as glazing, and offsite manufacturing.
“We’re pretty sure we can push the fabric as far as it can go and that will be world leading,” he said. “The challenge is more doing it for the right commercial price and that will require innovation in how we design and construct homes.
The outcome could have a significant impact on housebuilding as the consortium has 17% influence on the market, and the timber industry.”
“For the timber industry the challenge is ensuring we keep raw material prices competitive and maximising the structural, acoustic and thermal performance of wood and that might mean more composite solutions rather than just solid timber,” said Mr Dalgarno.
