Optimum pre-cooling guidelines: applicable to commercial buildings in Sri Lanka

Abstract

HVAC plants in buildings are generally started earlier than the building operation start time. That is to absorb the stored thermal energy in the building and reach the set indoor thermal condition by the time which the building operation is started. Cooling energy required during this period is called Pre-cooling energy and the early plant running time is called Pre- cooling time of the building. Thermal energy in buildings depends on pre-defined factors and predicted factors. Pre-defined factors include building envelope, envelope materials, type of HVAC system installed, Building interior, lighting, other internal heat gain factors, building operation pattern etc. Predicted factors include climatic condition in the region throughout the year. Due to the fact that precooling time is determined by both pre-defined and predicted factors, a thermal modeling study is more appropriate and recommended to assess the “pre-cooling demand and time” of buildings. The focus on this research study is to prepare an optimum “pre-cooling guidelines” for commercial buildings in Sri Lanka taking climatic variations also into account. World Trade center, Colombo, the largest commercial building in Sri Lanka was modeled in e-QUEST and results were analyzed with Colombo climatic data throughout the year to study the pre-cooling requirements (demand & time) and hence to derive a set of general pre-cooling guidelines applicable to any commercial building in Colombo.