Radiant floor is a low temperature heating and high temperature cooling system. Three parameters, cooling/heating capacity of radiant floor, uniformity of surface temperature distribution, and the lowest temperature in surface, are concerned most by designers and users of radiant floor. A simplified calculation of these parameters is presented in this paper. The error between experiment results in literature and calculation of cooling capacity and mean surface temperature is within 8% and 0.5 degrees C respectively. A simulation model is established to verify simplified calculation on surface temperature distribution. The absolute error between simulation value and calculation is within 0.2 degrees C. From the perspective of heat resistance, the most important limitation of cooling/heating capacity of radiant floor is heat transfer between floor surface and indoor environment. The thickness and heat conductivity of each layer has important influence on performance of radiant floor. The influence of water pipes should not be ignored. (C) 2012 Elsevier B.V. All rights reserved.