Method to evaluate window products with respect to a specific application

A two-node model of a room has been implemented in a computer program, WinSim, de-veloped for evaluation of thermal window performance in new buildings and in case of ret-rofitting. The program calculates the annual heating demand and the number of hours with indoor temperatures higher than a user defined limit as a measure of the indoor thermal comfort level.

WinSim is characterised by the limited amount of required input data. Guide-lines for calculation of the effective thermal capacity of the room is given, and results ob-tained with WinSim have been compared to results from an advanced building simulation program. Good agreement has been found between the two programs with respect to cal-culated annual heating demand and energy savings due to window exchange, and also the calculated indoor thermal comfort level is in the same range.

Based on the limited examples used for the comparison it can be concluded that WinSim is well suited for a fast and realis-tic evaluation of thermal window performance.