Low-sloped roofing systems, secured to structural decks to resist wind uplift, typically incorporate rigid insulation to conserve energy. Attachment of the insulation to the structural deck using steel fasteners and plates is a simple, economical and proven means of providing reliable securement. However, these metal components can adversely impact the roofing system's thermal performance by creating thermal bridges that channel heat flow out through the insulation during cold weather and inward during warm weather, increasing energy costs and negatively impacting the environment.
The roofing industry needs a practical means to predict the influence of thermal bridges to understand negative impacts and verify compliance with increasingly stringent energy codes. Heat loss and the corresponding reduction in insulating value due to these three-dimensional thermal bridges can be numerically modeled with software tools, but such simulations are time-consuming and dependent upon assumptions made during model development. Until recently, results of laboratory tests to validate models of thermal bridging have been scant.
To help foster greater understanding of the impact of thermal bridges, the presenters and other researchers from GAF, SGH and Virginia Tech, recently performed experiments under controlled laboratory environmental conditions to measure heat loss through fasteners, and in parallel developed computational simulations to compare tested conditions. In this session, the presenters discuss and compare the results and significance of both the physical models and computer simulations, to increase awareness of the influence of thermal bridges in the roofing industry and discuss practical means to reduce their impact.