District cooling potential for mega developments in Sri Lanka

Abstract

This paper presents the study related to existing buildings from a perspective of a district cooling system and its feasibility forthe projected mega developments in the country. This study is focused to show the District Cooling System (DCS) conversion suitability for a cluster of existing buildingsin the city of Colombo.Nine large scale buildings in Colombo having central air conditioning systems and having different cooling load patterns are selected for the study. The estimated cooling demand profile shows that the maximum cooling demand of the system is around 6,000 TR. Five suitable chiller options are considered for the cooling production based on the total capacity of the district cooling system and profile of the overall cooling demand.The maximum and minimum electrical energy savings that can be achieved by switching to the DCS from the existing individual systems are 6.42 and 5.67 million kWh per year. This energy savings is expected to result in a reduction in coal usage (assuming 60% of electricity generating by coal and oil, and rest by hydro) by about 1420 and 1240 tons per year respectively and reduction in CO2 emission of about 4,990 and 4,365 tons per year respectively.Discounted Cash Flow Analysis indicates that the best option has a NPV of LKR 396 million, IRR of 13.5% and benefit to cost ratio of 1.35. The sensitivity analysis of the best option reveals that even with the worst combined effect of the various parameters, the DCS is viable as it has a NPV of LKR 87 million, IRR of 11.8% and benefit to cost ratio of 1.07. Consequently, DCS is viable to implement in Colombo under the conditions and assumptions employed. It could be concluded that DCS could be a viable option for the forthcoming Colombo Port City Project and MegapolisDevelopment Projects since they can be implemented smoothly by planning the piping distribution network into the master plans of the projects.