Analysis of Passive Solar Design and Thermal Mass Optimization to Reduce Cooling Energy Demand of Existing Building

Half the global energy production is spent on building energy out of which, a major portion contributes to HVAC. With the projected increase in temperature under different climatic changes, the energy demand for cooling will increase significantly. If this increase in energy demand is not managed well, it can be a threat to the energy sector of a developing country like Sri Lanka, which predominantly relies on non-renewable sources for energy generation. The already hot and humid climate subjected to global warming will become an important factor for higher cooling energy demand forecasts. Hence, the prediction of energy demand and implementing cooling load-increasing mitigation tactics are important steps in building energy sustainability in Sri Lanka. Although steps have been taken to ensure energy efficiency in new buildings, the existing buildings pose a significant threat in terms of energy increase due to climatic change. There are different types of models adapted to predict the cooling load of existing buildings. This paper presents a hybrid data-driven model to calculate the air-conditioning demand predictions for several buildings in Colombo, Sri Lanka. It also uses the model to evaluate building thermal mass optimization and the usage of passive solar designs to reduce heat infiltration into buildings as cooling energy demand increases mitigation strategies. The model is used to predict the cooling load increase of eight selected zones of three different buildings for the year 2090 under two climatic change scenarios and to evaluate the energy-saving possibilities with the two countermeasures proposed. It was concluded that most zones will have a substantial reduction in cooling load: 20% on average by thermal load optimization with or without night-time ventilation, while the zones showed a significant cooling load reduction by up to 60% with optimized solar designs by 2090.