Two parameters affecting useful solar absorption are orientation and thermal mass. Solar energy absorption in buildings depends on these parameters in a complex manner particularly when considering large glazing ratios and large direct components of insolation. Therefore, where parameters of different zones in a multi-zone building vary, useful solar absorption will also vary. For higher northern latitudes, compared with south orientation, useful solar absorption differs by about 2%, 4% and 6% between large and small time constants for east, west and north orientations respectively. The smallest and largest differences are for cast and north orientations, respectively. Fenestration design should be a consequence of orientation and overshading, seeking to balance daylight, solar gains and heat losses. (C) 2002 Elsevier Science Ltd. All rights reserved.