CURTAIN WALLS AND THEIR POTENTIAL FOR REDUCING THE COOLING REQUIREMENTS OF BUILDINGS
Based on the European Directive (2002/91/EG) the European Parliament and Council decided that the Member States must apply minimum requirements as regards the energy performance of new and existing buildings, ensure the certification of their energy performance and require the regular inspection of boilers and air conditioning systems in buildings. Germany developed a directive for “Energy Saving” (EnEV) dictating a minimum standard on the energy performance of new and existing buildings. The calculation methodology are written in the German standard DIN V 4108-6 but also more detailed in DIN V 18599. Both standards include all the aspects which determine energy efficiency and not just the quality of the building's insulation. Therefore the choice of building components, heating, cooling and ventilation systems as well as lighting plays a special role in the energy performance of buildings. Building components influence on one side the calculation of heat loss and on the other side the calculation of heat gains. In the context of this paper investigations of curtain walls and their control of calculating solar heat gain in summer situation are presented. While the solar radiation can reduce the heating demand in winter an increased cooling requirement is assumed in summer. Curtain walls as opaque components are characterized in their thermal behavior primarily by the properties of thermal insulation material and the micro-climatic conditions in the air gap. The question that arises here is whether the temperature conditions in the air gap has an influence on the solar heat gains. This paper deals with experimental studies of curtain walls in summer situations and their influence to reduce the cooling requirement of buildings. For this purpose the paper is divided in three parts: (1) laboratory investigations, (2) CFD validation and (3) analysis of surface conditions influencing the solar heat gains.