Thermal Resistance Measurements with Heat Flow Sensors—Application to Spray-Applied Insulation Systems

Heat flow sensors are often attached to the inside surfaces of building envelope systems to determine the thermal resistances of these systems in the field. In this paper an alternative method for using heat flow sensors for this application is described. The heat flow sensors are attached, along with thermocouples, to a temperature-controlled test plate. The plate is generally placed against the outside surface of the building, and thermocouples are attached to the opposite surface. The plate is either heated or cooled for summer or winter conditions, respectively, and the heat flows and temperatures are measured after equilibrium is achieved. The method provides reliable thermal resistance values for envelope systems which are laterally uniform and useful approximate thermal resistance values for nonuniform systems. The application of the method to nonuniform building envelope systems is described, and experimental results are reported for insulation systems consisting of polyurethane, fiberglass, and cellulose spray-applied to metal decks.