The report looks at both the carbon and financial payback times that can be expected from typical domestic micro-wind turbine installations in a range of representative locations in Manchester, Portsmouth and Wick. It describes the financial and carbon costs of manufacture, installation and maintenance and compares them with the likely carbon and cost savings made by the electricity generated during their useful life.

The results show that, in windy locations such as the outskirts of Wick and parts of Portsmouth, domestic micro-wind turbines can generate sufficient energy to pay back their carbon costs within a few months to a few years and then go on to make a positive contribution to combating global warming, but in large, less windy urban areas such as Manchester they are very unlikely to ever pay back their carbon costs. Even when optimally sited outside of major conurbations financial payback is unlikely for all but the most efficient, low maintenance, low price turbines.

The report shows that performance is highly sensitive to relatively small changes in local wind conditions (standard performance calculations are usually based on wind speed databases, which don't account for surface roughness and local effects), installation and maintenance regimes (including associated transport costs) and expected service life.

Dr Martin Wyatt, chief executive of the BRE Trust Group said: “Micro-wind turbines designed to be mounted on both new build and existing homes could be very useful weapons in the fight against climate change. However, we need to significantly improve their whole life performance and provide independent assessment of that performance combined with simple advice on where to use and not use them, before we move to large scale installation. Without these improvements we are as likely to accelerate global warming as slow it.”

‘Micro-wind turbines in urban environments: an assessment’ is available in hard copy and pdf format from www.brebookshop.com