Modeling and calibration of lateral heat loss rate in measuring the R value of partly heated wall

An experimental apparatus (in-situ thermal test unit) and an analysis method have been developed for evaluating the thermal resistance of the building envelope on site. This system estimates the thermal resistance of a wall by heating the outside wall surface and measuring the surface heat fluxes and temperatures on both sides of the wall. The heating panel is attached to the outside surface to avoid the effect of outside weather and to keep the surface temperature constant. The inevitable problem of this kind of testing method is, however, the error caused by the lateral heat loss. The error rate increases as the thickness of the envelope increases. In this study, a calibration method has been developed that is able to compensate for lateral heat loss. The calibration model was made up through simulation using 3-dimensional heat flow calculation program (Voltra , Physibel). To validate this method, an experiment was conducted on mock-up blocks composed of insulation and bricks. The In-Situ measurement system adopting this calibration model could  be  expected  to  get  more  reliable  results  in evaluating thermal conductance on site.