Experimental investigation on thermal radiation exchange of horizontal outdoor surfaces

The results of an experimental investigation on thermal radiation exchange between a horizontal surface and the sky are presented. The surface under consideration is the horizontal roof of an air-conditioned room, built for the study of the energy behaviour of buildings. The roof is insulated to create an almost adiabatic boundary condition. The measurement of infrared and solar radiation, together with temperature measurement, was used to determine the net infrared flow, the solar flow absorbed and, by means of the surface thermal balance equation, the convection flow. The experimental investigations allowed the patterns of the surface thermal exchange forming at variation of the boundary conditions to be identified and the problem of evaluating the radiation exchange coefficient and the heat flow rate exchanged in the infrared to be addressed.