| National window rating and labelling programs in Canada and the U.S.A. have put an emphasis on the development of consensus test procedures for evaluating the energy performance of windows. In support of this, a calorimetric test apparatus has been developed and a standardized procedure established for the determination of fenestration solar heat gain coefficient (SHGC) using simulated solar irradiance. The procedure is referenced in a new Canadian standard on window performance evaluation as an alternative to computer simulation.; A calorimeter test cell designed for use at the Canadian National Solar Test Facility is described. The apparatus represents a second generation test cell, with several new features. Most notably, it employs a double-cell design concept that minimizes the error associated with thermally driven wall losses. As a consequence of this and other refinements, the apparatus offers enhanced measurement accuracy and has the distinction of being suitable for commercial testing purposes.; A test procedure for use with the above apparatus and facility is also presented. The effects of environmental conditions and irradiance spectrum encountered in the test facility were investigated using a window simulation model. The results indicated little sensitivity to environmental conditions, but that care must be taken when testing glazings with highly spectrally selective coatings to account for differences in the spectral distribution of the solar simulator from that of a reference spectrum.; To evaluate the new method and apparatus, the SHGC for nine high performance windows were measured. Comparison between measured and computer simulation results show the maximum difference in SHGC to be 0.03, with an average difference of 0.015. |
