Those buying property in the USA may get incentives to install a green roof.
Such roofs, typically covered with plants such as water absorbent sedum, are credited with saving energy through their insulation qualities, improving urban air quality and thus preventing the urban heat-trap effect, plus limiting storm water run-off, the Wall Street Journal reports.
According to Columbia University researchers, the energy saving from having such a roof is around 15 per cent, while senior resident fellow for sustainable development at Washington's Urban Land Institute Ed McMahon said the extra cost of installing such a roof would be recouped in five years.
New York has a scheme where owners of buildings who cover 50 per cent or more of their roof with vegetation can gain tax credits worth up to USD100,000 (GBP57,000).
Last week Cincinnati announced that it was also introducing a system of grants and loans to encourage green roofing.