The results of an experimental investigation on the exchange of radiant energy in the infrared band (lambda = 4-100 mu m) between the walls of a building and the surrounding environment, constituted in part by the sky and in part by the ground, are presented in this paper. The measures were obtained on a purpose built test module for studies and research on building energy. Through measurements of infrared radiation on a South facing vertical wall and on a horizontal roof, and of the relative surface temperatures, the radiant field between these surfaces and the outdoor environment was resolved in conditions of clear hourly diurnal and nocturnal sky. The investigation allowed for the determination of the hourly values of the radiative heat transfer coefficients between the vertical wall and the sky, between the vertical wall and the ground and between the horizontal roof and the sky. Furthermore, EN ISO 13790:2008, which is used for the evaluation of energy requirements of building air-conditioning, was considered and the various contributions used in order to evaluate the radiative exchange with the experimentally obtained values were compared. (C) 2012 Elsevier Ltd. All rights reserved.