Renewable energy in residential and commercial buildings

The renewable energy sources that can find utilization in house and commercial buildings are above all thermal solar and photovoltaic, even if wind and geothermal energy can sometimes be used. Biomass can be used when available, provided that modern equipment control possible pollutants. A priority action before turning to renewable energies is a careful analysis of all the possible energy savings. Solar thermal energy can provide a useful contribution in the frame of solar passive architecture. Both solar thermal and photovoltaic find hardly enough room in the urban environment. A possible new solution is PV cogeneration where the same component provides at the same time heat and electricity.