Energy effective design of commercial building envelopes in the sub-tropical climate.

This paper reports the analysis of the thermal performance of building envelopes of high-rise commercial buildings in the subtropical climate and their interactions with cooling system. Building constructions of commercial buildings in Hong Kong have been investigated and categorized. Their thermal performance and the resulting chiller load is studied with the building energy simulation tool DOE-2. lD. The characteristics of subtropical climate, coupled to high internal gains of commercial buildings, are discussed. Accordingly, an approach of assessing the year-round envelope heat gains summed for all hours of net heat flow into the building is proposed.  Parametric runs are conducted to study the effect of individual envelope features on the heat gain. Sensitivities of the envelope parameters are determined, and proper design of envelopes for energy effectiveness are discussed. The interaction of envelope designs on daylighting and cooling requirement is also investigated. It is concluded that the possible range of cooling energy requirement subjected to influence of envelope designs is substantial. Professional input in the design of building envelopes for energy effectiveness is needed.