Walls Thermal Resistance Measurement with an Energy Room Method: Uncertainty and Analysis of Different Approaches

Abstract

This paper presents the development of a test method to determine the heat loss of an energy room. A complete room 3.42 x 3.62 x 2.29 m3 has been built in an environmental chamber. Five of the six faces of the room have been highly insulated to reduce the heat loss and the uncertainties of thermal resistance of the studied wall (front wall). It has been done by using vacuum insulation product. The room is instrumented by 100 thermocouples, which measures surface and environmental temperatures. The energy room was modeled on COMSOL Multiphysics to evaluate all the heat flow through the different walls of the room. To ensure the quality of instrumentation and insulation, the energy room has been qualified with a wellknown insulation material installed on the front wall. Three methods have been used to determine the uncertainties of measurement: a calculation based on thermal resistance measured by a guarded hot plate, the use of a co-heating method in a stationary state, and the use of heat flow sensors glued the front wall. It has been demonstrated that the effect of the homogeneity of the front wall on the uncertainty of result. The uncertainty associated with the overall thermal resistance of the structure is between 10% and 20%. Although the presence of an air gap in the front wall increases the uncertainty of heat flow sensor, the co-heating method presents a suitable solution. This energy room can be used to evaluate the effect of insulation product installation or to study complex system.