Phase change materials absorb a large amount of energy as latent heat at a constant phase transition temperature and are thus used for passive heat storage and temperature control, example applications include electronics, and storage of perishable items. Encapsulated phase change materials incorporated into gypsum wallboards of buildings may be suitable for absorbing solar energy directly, reducing temperature rise. Improvement in human comfort is to be expected due to a decrease in the frequency and magnitude of internal air temperature swings, maintaining the temperature closer to the desired set temperature passively for a long period of time. This paper summarises the results of a detailed theoretical investigation and analysis of thermal energy storage and temperature control achieved using passive building construction elements incorporating phase change materials. The predictions detail the effects of using various quantities of different PCM materials with phase change temperatures of 28 and 43 degrees C incorporated into a selection of wall constructions for selected ambient conditions of temperature and insolation. From this parametric study, optimum arrangements are proposed. (c) 2006 Elsevier B.V. All rights reserved.