Domestic insulation not 'silver bullet,' says Arup expert

Most of the big gains in improving the heated energy efficiency of the existing housing stock have already been made but resulted in no carbon benefit, an expert from Arup told Building this week.

Few houses have open fireplaces or single-glazed windows, said Chris Twinn, Arup’s building engineering sustainability group leader. Whilst Twinn refused to be drawn on exact percentages, according to Carbon Trust figures, around 55% of a building’s heat would be lost through these apertures with a further 25% being lost through the roof and another 10% through the walls.

However, a survey of the existing domestic stock published by the BRE in 2003, found that 82% of houses already had double-glazed windows and 94% of homes had some loft insulation. 37% of homes have cavity wall insulation already, the BRE found.

"We have already thrown a great deal of money over the years at the existing stock but to little effect," Twinn said. "Instead we are getting used to the warmer temperatures that this reduced heat loss can deliver and so end up using the same energy as before.

"Instead of gathering around the TV in a single room and taking hot water bottles to bed, we continuously heat every single bedroom in the offchance we might want to use a laptop or watch DVD in there. Insulation is not a silver bullet."

He added that concentrating on new stock was sensible and pointed out that these buildings will comprise 30% of the stock by 2050 if the government’s targets are met.

To reach the UK's 80% carbon reductions now being considered, Twinn believes we need to improve energy delivery to our homes. He added that said the installation of district CHP systems like Hammarby Sjostand in Sweden was a sensible way of reusing heat. Arup’s work for Dongtan in China, would show a more integrated approach to heat and power, he said. The city, near Shanghai, will use 64% less energy than a comparable settlement, projected figures suggest.