Building orientation plays a major role in the building envelop heat gain. A proper building orientation of the building will reduce the solar heat gain to your building and will make good use of day light as well. Hence it is important to consider the building orientation as well as material selection for the building envelope to optimise the building energy consumption. Maximum heat gain in the building is from the south facade/windows, hence the designers can also consider the extended shading devices in order to reduce the heat gain.
The plate size of the building also affects the building heat gain. If there is a building having the square plate size, the envelope surface area (peripheral area) will be minimum and if the building is having a long rectangular plate size, the envelop area will be larger. The larger surface area will lead to the larger heat gain in the building and the smaller surface area will have the lower envelop heat gain. However the day lighting in a square building plate area will not be good as much of the floor area in a square building is far from the perimeter lighting. Hence the building plate size selection is a trade off between the envelop heat gain and the day-lighting accessibility.
In the following example we have compared the building orientations for different design alternatives.
The results indicates that rectangular shaped Building consumes more energy than the Square because of large area exposure to Heat. If we change the orientation of rectangular building and put the smaller surface area towards south this reduces the energy consumption in the building 4062 MWh 3852 MWh.
There are few lessons we can conclude from this exercise is that the building envelop designing is a trade-off between the external heat in the building and the day-lighting requirements. An optimum solution for this is a site specific requirement. If the building is a data centre and you do not have too much of day lighting requirements, then go for a larger plat size and reduce the building envelop surface area and thereby reducing the overall envelop heat gain. However if the building is a commercial building, then the day-lighting requirement is a critical and you need to find out a trade-off solution for the optimum plate size of the building in order to reduce the building heat gain.