Images courtesy RIMA International Feature Building envelope and equipment applications By David W. Yarbrough, PhD, PE T he effective specifi cation and installation of all types of thermal insulation requires an understanding of the factors affecting performance. The specification of a thermal resistance (RSI or R-value) alone does not ensure the intended heat-flow reduction. In virtually all cases, space for insulation must be provided and insulation material must be installed to conform with the manufacturers’ requirements. In the case of reflective insulations, factors such as heat-flow direction, air-space dimensions, and location in the building envelope should be considered. 1 The specification of conditioning equipment and reliable prediction of utility use requires understanding of the variation of the performance 76 March 2014 CC_March_14.indd 76 of any selected insulation with, for example, temperature, air movement, and thickness. In addition, the thermal performance of enclosed reflective air spaces (reflective insulations)depends on heat-flow direction, placement of low- emittance surfaces, and temperature differences. This article discusses factors to be considered in the specification of reflective insulation systems. In the United States, the labelling and specification of reflective insulations for use in the building envelope or to insulate equipment is set out in ASTM C1224, Standard Specification for Reflective Insulation for Building Applications. However, Canada has not yet published a standard or guide for the evaluation of reflective insulation products. Co nstruction Canada 2/11/2014 4:49 PM