Laboratory Tests of Window-Wall Interface Details to Evaluate the Risk of Condensation on Windows

Abstract

Abstract The development of alternative details to manage water intrusion at the window-wall interface has produced a number of novel approaches to detailing the interface between the window and the adjacent wall assembly. Many of these approaches advocate the need to provide drainage at the rough opening of the window subsill, given that the window components themselves are susceptible to water entry over their expected life. Depending on the types of windows used and the cladding into which the windows are installed, there arise different methods to provide drainage that may also affect air leakage through the assembly. This in turn may give rise to the formation of condensation along the window, at the sill, or along the window sash and glazing panels. Hence, there is a need to determine if, under cold weather conditions, specific interface details that incorporate sill pans provide a potential for condensation on the window components in which air leakage paths may be prominent at the sill or elsewhere on the window assembly. The paper reports on a laboratory evaluation of conditions suitable for the formation of condensation at the window frame perimeter of the interface assembly as a function of both temperature deferential and air leakage rate across the test assembly. A summary of the laboratory test protocol is provided, which includes a description of the test setup and apparatus, fabrication details of the specimen, information on instrumentation and calibration, and experimental results for one type of window (flange window). In parallel, preliminary simulation results were presented and compared to those obtained from the experiment using the commercially available thermal software BISCO.