Determination of the Optimum U-Values for the Building Envelope

The limit values of the overall heat transfer coefficient for opaque components of building envelope, which are determined by the energy conservation regulations or standards, are independent from orientation and also from dimensions of opaque and transparent components of the envelope. However, these parameters significantly effect the thermal comfort of occupants in a room. The well-known comfort standards give the optimum and limit values of operative temperature which represents the combined effect of inner surfaces and indoor air. The methodology introduced in this study is to determine the optimum “U” value for opaque components based on these comfort values of operative temperature given by the comfort standards. The results of the sample calculations to determine the optimum “U” values, in accordance with dimensions of opaque components and dimensions and inner surface temperature of transparent component, are given in the paper.