ODPM (2006) Approved Document L2a & L2b – To reduce energy consumption in buildings by 25% (vs ADL 2002) The Energy White Paper (2007) – 10% of UK Electricity to be from renewable sources by 2010 & 20% by 2020
The thermal benefits of a green roof mean that during the summer months the green roof keeps the roof cool. This not only keeps the temperature inside the building down but it also keeps the temperature at roof level down making solar panels work at their most efficient rate. Whilst these benefits are not be included in ‘U’ value calculations, numerous studies have outlined the energy reductions, with a very conservative estimate being 11.25kWh/m2/year.
Green roofs actually keep the roof level in summer months between 20-28 degrees centigrade. 25 degrees centigrade is the optimum temperature for a solar panel and any increase above thirty degrees the solar panel loses half a percent of efficiency every degree.