Thermal Break Strategies for Cladding Systems in Building Structures

PROJECT SUMMARY

Prescriptive energy code design procedures such as those included in the IECC do not account for the thermal bridging caused by shelf angles and other structural steel elements that cross the thermal envelope plane. Buildings designed using these standards that include thermal bridges at elements such as shelf angles will not meet targeted energy performance, increasing energy costs and driving climate change and other environmental problems. Green building codes such as the IGCC and standards such as LEED are driving the design and construction of more energy-efficient buildings, but these standards rely upon energy codes and energy design procedures that do not effectively account for thermal bridging. Thermal bridging should therefore be addressed for high-performance steel buildings to meet the market demand for better energy performance. The goal of this research is to substantiate the performance of innovative approaches to addressing thermal bridging that designers and code-writers can immediately implement in practice. One important issue that will be addressed is that the steel design specification referenced by building codes does not permit the use of FRP shims between steel members fastened with high-strength bolts. This project will investigate whether FRP shims can be safely used in applications such as shelf angle supports, roof supports, and balcony supports. The key goal of this project is to explore and validate the structural and thermal performance for several concepts and develop associated design recommendations for mitigating the loss of energy in steel building structures through thermal bridging by using FRP shims or members for shelf angles, roof posts, or balcony beams, intermittent steel shelf angles, or comparable solutions.