Field Measurements of Steady-State Thermal Transfer Properties of Insulation Systems

Abstract

A technique to assess the thermal performance of building envelope systems in the field has been developed. The thermal resistance of these systems is measured with a 1.22-m-square temperature-controlled test plate to which heat flow sensors and thermocouples are attached. The plate is placed on top of an insulated roof system or against an insulated wall system, and thermocouples are attached to the opposite surfaces of the envelope systems. Measurements can be made without disturbing the structure of the envelope systems by using test plate temperatures approximating normal outside surface temperatures. The test plate is either heated or cooled and temperatures and heat flows are measured after equilibrium is achieved. The method provides reliable thermal resistance values for envelope components which are laterally uniform and useful thermal transfer property information for more complex envelope systems. The application of the method to a single-ply expanded polystyrene insulated roof, sprayed-on polyurethane roof insulation systems on both metal and concrete decks, and an insulated metal-stud wall system is described.