星空传媒

Now Gordon Brown has jumped on the environmental bandwagon with the announcement in his recent budget that any new zero-carbon home built up to 2012 will be exempt from stamp duty. Even with the broadest definition of what constitutes a zero-carbon home, the total number of new British homes built as a result of this benefit will be negligible.

It is a situation that is unlikely to change in the immediate future. Last month鈥檚 feature on Richard Quincey鈥檚 endeavours to build a low energy home for his family (BSj 03/07), highlighted the challenge faced by designers pursuing the zero-carbon goal. Quincey is an experienced engineer with expertise in low energy design, yet the disproportionate costs of pursuing the zero-carbon option meant he opted for a design that used 鈥渧ery little鈥� energy rather accept the diminishing returns of a zero-energy solution.

The law of diminishing returns is cited by Paddy Conaghan as a reason for the government to rethink its policy on zero-carbon homes (p 21). Conaghan argues that the cost of achieving the final 20% cut in carbon is likely to be as much as achieving the first 80% cut and that engineers could use this money to better effect on more productive carbon-reducing technologies.

Given that new homes account for only 1% of the housing stock in any particular year, perhaps the government鈥檚 focus on zero-carbon new homes is wrong. If Brown was serious about the environment, surely the government would have been better advised to pursue a commitment to improve the energy efficiency of millions of existing homes. A policy promoting an incremental improvement in their efficiency of, say, 1% each year would surely outweigh the environmental benefits produced by building all new homes to zero-carbon standards. Such a move would show householders that the government takes energy consumption seriously, whereas providing tax relief on a few hundred zero-carbon homes does not.