This work describes a model developed to simulate a radiant floor system with PCM in simple building types. The building simulation model has been validated by comparing its behavior with Energy Plus. The PCM radiant floor model is based on a one-dimensional finite difference scheme where the effective capacity method is used for PCM simulation. Some adjustments have been made to this one-dimensional scheme so that the thermal effect of two-dimensional heat transfer within the radiant floor slab is taken into account. The results of an analyzed case study are also presented in this paper. Here, the PCM floor heating system is fed by a heat pump which mainly operates during night time, thus reducing the costs of electric energy consumption. (C) 2011 Elsevier B.V. All rights reserved.