Although the solar thermal technology is mature with competitive prices, it is not yet playing the important role it deserves in the reduction of buildings’ fossil energy consumption. The generally low architectural quality characterizing existing building integrations of solar thermal systems pinpoints the lack of design as one major reason for the low spread of the technology. As confirmed by the example of photovoltaics, an improvement of the architectural quality of building integrated systems can increase the use of a solar technology even more than price reductions and technical advances. As opposed to electricity produced by photovoltaics, heat is very sensitive to transportation losses. Therefore solar thermal collectors have to be mounted very near to the consumption place – i.e., on the building itself – making it even more urgent to correctly address the architectural integration issue.