The largest ever study of the impact of wind turbines has concluded that they have no effect on property prices. A paper from the US Lawrence Berkeley National Laboratory looked at the sales of 7,500 homes between a few hundred metres and 15 km from a wind farm. In a very sophisticated and peer-reviewed study using a wide variety of different mathematical models, the authors conclude that the impact of nearby wind turbines on the prices of homes is negligible. In summary, ‘homes located near the wind facilities that transacted more than once were found to have appreciated between those sales by an amount that was no different from that experienced by homes located in an area many miles away from the wind facilities’. It sounds a simple task to determine whether wind turbines affect property prices. Just observe how the prices of home closer to wind farms change in relation to house prices nearer away, we’d quickly say. Researchers have found it far more difficult than they expected and only two studies have ever been published in academic journals. Too many factors intervene to make comparison easy. For example, homes close to wind turbines might typically be in areas of high landscape value and such homes might have inflated in relation to houses in large towns. As a result of the myriad conceptual difficulties, academic studies have relied on unreliable estate agent opinions and used only small sets of data. Moreover, few researchers have actually been to the homes in their study to determine, for example, the degree of visibility of the turbines.

The Lawrence Berkeley study seems a real advance on previous work (though this makes it extremely difficult to understand). A large database of homes was used by the researchers and every single house in the study was visited and assessed. The overall conclusion is likely to be resilient, and is in line with the best other surveys around the world. No statistically robust effect on house prices arising from the construction of wind turbines can be observed.

That said, it’s important to note some of the individual findings, even if they don’t meet conventional tests of statistical reliability.

1) There is some evidence that houses very close to a turbine might lose 3-4% of their value but this effect may fade over time. (The authors of the study point out that this is similar to the effects observed on house prices when new roads are constructed or high voltage transmission lines constructed).

2) The degree to which a turbine is within view of the house has no measurable impact. In fact, homes with the most visible turbines had higher prices than expected.

3) There may be a negative effect on nearby house prices at the point at which a wind farm is mooted. But this effect seems to fade completely when the farm is constructed. (This finding has been seen in other surveys as well, including those in the UK).

4) Adjusting for property size and other variables, homes more than five miles from a wind turbine on average sold for less than homes closer by.

The study concludes ‘no evidence is found that home prices surrounding wind facilities are consistently, measurably and significantly affected either by the view of wind facilities or the distance of the home to those facilities. Although the analysis cannot dismiss the possibility that individual homes or small numbers of homes have been or could be negatively impacted, it finds that if these impacts do exist, they are either too small and/or too infrequent to result in any widespread, statistically observable impact’.

The UK Environment ministry is reported to have commissioned a study of the impact of wind turbines on house prices. Although most people regard it as ‘obvious’ that wind farms affect property values, this huge US study should prompt re-examination of this conclusion and oblige DEFRA’s researchers at Frontier Economics to recognise the high degree of difficult in making robust assessments.