How the Same Wall Can Have Several Different R-Values: Relations Between Amount of Framing and Overall Thermal Performance in Wood and Steel-Framed Walls PDF

Is it possible that the same wall material configuration can be described in different documents or publications with several different R-values? Is it possible that the same code R-value requirement can be satisfied by wall configurations of significantly different thermal performance characteristics?

The answers to both questions is yes, it is very likely.

What is even more surprising, in most cases of wood or steel-framed constructions, these confusing answers have very simple sources: the amount of framing considered for R-value analysis and the type of wall cavity insulation.

This paper documents, experimental and numerical analysis of thermal effects of various configurations of structural components in wood and steel-framed walls. In addition, consequences of installation imperfections in cavity insulation on thermal performance are analyzed. The main purpose of this work is to incorporate these findings into whole- building energy calculations and initiate discussion of changes in existing code requirements for the thermal performance of walls.

Presented at Thermal Performance of Exterior Envelopes of Whole Buildings X – December 2007

Units: Dual