Heat resistance measurements with the portable calorimeter box

The heat resistance of wall section materials has been investigated under laboratory conditions, but reliable measurements in-situ with non-steady weather conditions are not yet available. The portable calorimeter box is designed to make field measurements to test the thermal performance of building envelopes. The experimental setup and the equipment for thermal measurements are described, as well as the computer program for data reduction. The characteristics of the portable calorimeter box and the problems of non-controllable test conditions have been investigated. Forty experiments were completed. Sixteen preliminary experiments investigated problems associated with insufficient setups; such as a short duration, only partly reported data, and the influence of solar radiation. Twenty-four tests measured the heat resistance of test specimens. The problems with measurements of temperature differences smaller than 15 F between outside and inside are shown. The influence of different thermal radiation emissivity inside the portable calorimeter box and non-zero controller settings is demonstrated. It is concluded that the portable calorimeter box is a device that can measure the heat resistance of building envelope sections with an accuracy better than 10%