A paraffin/water phase change emulsion is a multifunctional fluid in which fine paraffin droplets are dispersed in water by a surfactant. This paper presents an experimental study on the heat capacity of an emulsion containing 30 wt.% paraffin in a test rig. The results show that the heat capacity of the emulsion consists of the sensible heat capacity of water and that of the paraffin as well as the latent heat capacity of the paraffin during the phase transition solid-liquid. The emulsion is an attractive alternative to chilled water for comfort cooling applications, because it has a heat capacity of 50 kJ/kg from 5 to 11 degrees C, which is two times as high as that of water in the same temperature range. (C) 2010 Elsevier Ltd. All rights reserved.