Thermal bridges : a non-computerized calculation procedure

This study presents a non-computerized calculation procedure for steady state two-dimensional conductive heat losses through thermal bridges. The heat flow is divided into distinct flow paths based on physical considerations. A resistance is derived analytically for each flow path. These resistances are combined into a net work. The network simulates the construction. Calculating the total resistance of the network gives the thermal resistance of the construction. The algorithm is compared with a finite forward difference method. The relative error on the linear thermal transmittance of the thermal bridges calculated does not exceed 10%. The absolute error on the mean surface temperature is approximately 1°C and independent of the type of construction. The minimum inside surface temperature can be estimated in only a few cases; the absolute error is approximately 0.5°C. The algorithm is devel oped mainly for designers. Its simplicity and the possibility it offers for quick and ac curate control calculations makes it an ideal design tool. It can be programmed in Lotus for specific applications of a designer. It is ideal for prevention of condensa tion, more so than predicting heat loss (or gain).