Experimental Study of Temperature Distributions Across Two Curtain Wall Systems PDF

Metal curtain walls are widely used in the building industry and offer many advantages including space saving, high quality in manufacturing, light weight, significant aesthetic freedom, and rapid construction. The recent concerns for energy conservation and improved indoor thermal comfort require improvements in their performance. Initially, the metal curtain wall industry grew within the metal window industry, and standards developed for windows are also used to evaluate the performance of curtain walls. However, the heat flow through curtain walls is more complex than in windows and depends to a great extent on the design details. For example, the application of high-performance glazing units to increase the thermal resistance of the envelope can be compromised by the thermal bridges at the joints, such as the fastening screws and the return of back-pans. To evaluate the overall thermal performance of curtain walls accurately, it is necessary to study the complete wall assembly. An experimental study of temperature distribution across two curtain wall systems is presented in this paper. A two-story full-size specimen (12.5 by 22 ft), incorporating various design details including spacer type, the glazing unit, the thermal break material, and the back-pan design, was tested in an environmental chamber under steady-state and periodic winter conditions. The temperature distributions on glazing panels and at the mullion sections are reported, and the condensation resistance factors for the glazing and the frame are calculated. The results of the preliminary analysis reveal the relative impact of these design details on the performance of the respective curtain wall systems. This is an initial report on the results of this experiment, and additional information will be published as the study proceeds and additional experimental data are analyzed.

Authors: Hua Ge; Paul Fazio, Ph.D., P. Eng.; Jiwu Rao, Ph.D.
Citation: Thermal Performance of the Exterior Envelopes of Buildings VIII
Keywords: December, Florida, 2001