C002 -- A Comparison of Calculation Methods for Thermal Bridges in Building Enclosures ✓ Most Recent

Thermal bridges in the exterior enclosures of buildings can impact energy performance, occupant thermal comfort, and condensation potential. European energy performance standards have established calculation methodologies for thermal bridges which have been adopted by the Passive House certification standards. More recently, regional building codes in the United States (U.S.) including the 2020 New York City Energy Conservation Code and the 2017 District of Columbia Energy Conservation Code, are requiring designers to account for thermal bridges in building enclosure design. To comply with these codes, designers may select from tabulated and generic pre-calculated values of common enclosure thermal bridges or use a numerical calculation method, often employing a computer simulation tool. This paper provides an overview of various thermal bridge calculation methodologies, including those presented in American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) and International Organization for Standardization (ISO) standards/guidelines and local energy codes. The authors use two linear thermal bridge case studies to demonstrate the differences between methodologies. Through these linear thermal bridge case studies, the authors show that tabulated and generic pre-calculated values in some cases are more conservative compared to project-specific calculations, and in other cases are less conservative. See more