Claims by the boss of John Laing that it has taken a financial hit on its farm here after assessing that the wind will blow less strongly than expected has perplexed other energy suppliers.

John Laing, the giant infrastructure firm, said it is taking a multi-million writedowns on a windfarm it owns in Co Tipperary and in Germany because it estimates that the wind will blow less and generate less power over the next 10 to 15 years than it once anticipated.