Demands for greater thermal comfort coupled with architectural concepts featuring extensive glazing are leading to an increasing demand for air conditioning in office, commercial and residential buildings. Active cooling of interiors using cold-generating systems becomes necessary when passive systems can no longer cope with the cooling load. The cold can be produced using conventional compressor technology, simple adiabatic cooling or solar cooling technology. In Central Europe, around 50 to 200 cooling hours per year are generally assumed for residential buildings, and 1,000 hours for administration buildings.