LV-22-004 — Development of a U-Factor Calculation Procedure for Cold-Formed Steel C-Shape Clear Wall Assemblies

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The objective was to develop a simplified U-factor calculationprocedure to evaluate an extensive range of cold-formedsteel C-shape clear wall assemblies that can be used for energyanalysis and code compliance. The scope addresses five wallstud dimensions, four stud spacings, four designation thicknesses,nine cavity insulations, and seven insulated sheathings,for a total of 2128 cases. The technical approach was to(1) analyze each case using the THERM 7.6 two-dimensionalheat transfer computer program to determine the U-factors;(2) apply the parallel path calculation procedure for the steelC-shape and cavity insulation paths; (3) calculate the “effective”thermal width of the steel C-shape path, which wasdefined as the overall thermal zone (OTZ); (4) develop a seriesof regression equations using Minitab to correlate the OTZwith the key construction variables; (5) develop a Microsoft®Excel® spreadsheet that integrates the regression equationswith the parallel path procedures; and (6) use the spreadsheetto calculate the U-factors for the 2128 cases. The U-factorresults from the spreadsheet were compared to the THERM 7.6results and the average difference for the 2128 cases was0.27% with a standard deviation of 3.11%. Based on theseresults, the simplified U-factor calculation procedure wasdeemed acceptable for use in energy analysis and developingcode compliance criteria for ANSI/ASHRAE/IES Standard90.1 and the International Energy Conservation Code (IECC).

Product Details

Published:

2022

Number of Pages:

8

Units of Measure:

Dual

File Size:

1 file , 1.1 MB

Product Code(s):

D-LV-22-004

Note:

This product is unavailable in Russia, Belarus