The aim of the law is how the renewable energies should increase his proportion in the hot water production and the heating of the buildings, and hereby reducing the import dependence of the fossil energy sources. The regulation concerns house-buildings starting after 31st December 2008, accordingly for the part of hot water supply and heating of the buildings cover from renewable energy. As a result of this until 2020 the measure of a thermal energy supply has to rise to 14 %. To the realisation of the claim there is need onto the support of the heat supply.