A comparative simulation study of solar flat-plate collectors directly and indirectly integrated into the building envelope

Simulation analyses for solar combisystems (domestic hot water productionand space heating) with different levels of collector quality (atmospheric and evacuated flat-plate collectors) and different types of façade integration (direct, indirect) have been performed. For the direct integration of solar collectors into the building facade, a simple collector-facade model has been used (TRNSYS) while indirect integration with a naturally ventilated air gap between collector and facade has been investigated with a newly developed collector-facade model representing the air flow in the gap induced by wind or buoyancy (TRNFLOW). The highest performance has been achieved by direct integration of high efficient evacuated flat-plate collectors directly integrated into the façade.