Especially wood/aluminum windows are currently very popular: They are a perfect match of the heat protection properties coming with wood and the weather resistance of metal. With the external aluminum cladding there is no more need to repaint. The windows will still be looking good even after decades of use.
Due to their frame material, modern insulation systems, and effective heat protection glazing, wood/aluminum windows reach all values required by German energy saving regulations (EnEV 2009) without any problems and provide the appropriate U-values for all relevant demands. Combined with highly insulating frames and triple heat protection glazing even the tightened requirements of EnEV 2012 can easily be fulfilled. Hence, wood/aluminum windows are already perfectly suitable for being used in low-energy and passive houses.
Private builders are more and more interested in conserving (or even increasing) the value of their homes with high-quality, durable, and comfortable windows. In addition, many homeowners decide to take energy-related modernization measures to counteract the soaring energy costs. Bear in mind that windows have a life expectancy of more than 35 years! Therefore only the best should do.