The designer should ensure that the long axis of the built form is oriented east-west so that the long side of the building faces north and south. This allows to place the majority of the windows into the north and south walls and accordingly to reduce solar heat gain. As a general rule of thumb, the optimum aspect ratio of the built form should be 1:2-1:3 for climatic zones nearer to the equatorial zone and lesser at the higher latitudes (Cole et al. 1995; Yeang 1999).
Arrangement of the Building Masses
The arrangement of the building masses should be considered as a factor in bioclimatic design as its position can help to promote or reduce heat gain. In arid and tropical regions, the service cores of the building should be located on the east and west sides of the building, so as to help shade its form from the low angles of the sun during the major part of the day. Studies show that double-core configuration, with window openings running north and south and cores on the east and west, can achieve significant savings in air-conditioning. The advantage of using this placement is to reduce solar heat gain into the internal user spaces and provides a thermal buffer zone to the hot sides, while at the same time maximizing heat loss away from user spaces. There are several benefits in using the peripheral service core:
- • No fire-protection pressurization duct is needed, resulting in lower initial and operating costs,
- • Provision of natural ventilation to the lift lobbies and thus further energy savings, solar and wind buffer effects,
- • Provision of natural sunlight to the lift and stair lobbies,
- • A safer building in event of total power failure or fire,
- • Better awareness of the place by providing a view out for users.