The American Iron and Steel Institute (AISI) has published the findings from research conducted to support the development of a calculation methodology for determining the U-factors and R-values for wall assemblies containing cold-formed steel. The research project was conducted by Morrison Hershfield Ltd (MH) and involved detailed thermal modeling simulations of 27 steel stud assemblies which varied by insulation thickness, insulation placement and steel stud depth. A summary of the project, findings and analysis are published in “RP18-1: Thermal Analysis of Cold-Formed Steel Wall Assemblies.” A free download is available here (52 pages).
To make cold-formed steel design more efficient for building construction professionals, AISI is in the process of developing a consensus standard that contains simplified calculation methodologies for determining the thermal performance of generic cold-formed steel assemblies. Current methodologies for making these calculations vary depending on the code, standard or guide being used, and this consensus standard is intended to serve as the primary source for evaluating the overall thermal resistance of cold-formed steel-framed assemblies. The methodologies can also include either simplified hand calculation methods or more complex methods such as hot box testing, 2D and 3D thermal modeling approaches that may not be widely available or practical to conduct in every situation.
“Our goal is to use the data gathered from this research project to develop a practical means of calculating U-factors for these assemblies without the direct need for additional software or testing apparatus and to provide greater accuracy in results over current simplified methods,” said Jay Larson, P.E., managing director of AISI’s Construction Technical Program. “A new calculation methodology will save time and costs for engineers and designers while ensuring that cold-formed steel framing remains a competitive option for mid-rise building construction.”