9:00 am - 10:00 am | Room: Sinatra | Session Chair: Peter Adams

High Performance Envelope Design

Impact Of Solar Reflectance Of Glazing Adjacent Roofs

Exposed roof membranes are designed to withstand exposure to direct solar radiation.  However, when adjacent to reflective glazing, flashing, and/or cladding, the roof membrane will be exposed to additional radiation and elevated temperatures. Elevated temperatures can cause issues related to membrane bonds, increased blistering, and in some cases holes in the membrane. There is anecdotical evidence and reporting of the consequences, but no definitive studies show how much of an impact these adjacent windows and walls can have on roof temperatures.

The objective of this paper is to highlight the findings of a research study done at the University of British Columbia, where a roof section adjacent to clearstory windows was monitored over a year and compared to 3D thermal simulations. The study investigated the impact of membrane colour, various overburden, overhangs, and varying reflectivity of adjacent window and walls scenarios.

The findings show how solar reflectance increases the temperature of the roof membrane, which can increase the risk of blistering and membrane degradation. The paper is directed towards designers, researchers, contractors, manufacturers, and building owners. It is intended to increase awareness of the impact of solar reflectance from adjacent windows and walls as well as to provide guidance for minimizing the risk.

Patrick Roppel, Evoke Buildings Engineering Inc.

Patrick is a building science specialist with over 19 years of consulting experience related to building science and energy efficiency. Patrick’s focus in recent years has been providing tools and guidance to the industry to help practitioners make informed design decisions related to constructability, thermal, energy and hygrothermal performance.