Wind power: Ethical funds have been investing heavily in wind-power companies such as Vestas with good reason. For many countries, including Ireland, wind power is now viewed as one of the only economic and viable ways to reduce dependence on fossil fuels such as oil, gas and coal. The sector is also helped by Government targets for the use of renewable energy.

Forestry: Although it has yet to add any trees to its portfolio, Ireland's National Pension Reserve Fund has allocated 0.5 per cent of its total fund to investment in forestry, on the basis that purchasing land for afforestation is well-suited to long-term investments such as pensions.

Forestry also happens to be a highly green activity that is supported in the Republic by tax breaks.

Telecommunications: Not all of the stocks held by ethical funds might seem obviously green.

The funds often include telecommunications companies such as Vodafone, which produce comparatively low levels of industrial waste and in theory also help reduce the need for carbon-emitting business travel.

FTSE4 Good index: Launched in 2001, the index excludes companies operating in the tobacco, weapons and nuclear power station markets.

Some "negative screens" are being removed and replaced with stringent entry criteria, allowing companies that market breast milk substitutes and mine uranium to qualify for the index. At its last review, seven companies were deleted from the index for failing to meet environmental criteria, while toymaker Hasbro was removed for failing to meet supply chain labour standards.