Heat transfer barriers and other practical difficulties do currently hamper the development and application of (phase change materials) PCM-wallboard systems. In this study thermal performance of randomly mixed PCM and laminated PCM-wallboard systems have been numerically evaluated and results compared. The laminated system displayed up to 50% increment in heat flux enhancement and about 18% increase in heat transfer rates. Consequently, the laminated PCM-wallboard system has greater potential for heating and cooling application in buildings than the randomly mixed system. Experimental validation and investigation into manufacturing techniques are however needed to establish the commercial viability. Copyright (C) 2002 John Wiley Sons, Ltd.