Benefit analysis of air conditioning systems using multiple energy sources in public buildings

Abstract

A multiple energy source air-conditioning system was developed for large office buildings in Beijing, China to reduce the energy consumption and improve the energy utilization in public buildings. Three systems are compared with an air source heat pump system, a ground source heat pump coupled with an air source heat pump system and a solar assisted ground source heat pump coupled with an air source heat pump system. Cost-benefit analyses are given for each type of air conditioning system. The building load was computed using the DeST simulation software. Economic indicators are used to evaluate the systems economics in terms of the initial investment, life cycle cost (LCC), operating cost, payback period, energy conservation rate and cooling and heating cost in hourly moments. The results indicate that the multiple energy sources system has better energy conservation and economics. For a solar heating fraction of 40% to building loads, the required solar heat collector area is 135m2, the energy conservation rate is 43.18% and the payback period is 2.76years. Although the initial investment is greater than for the other systems, the operating costs are lower at 65,932CNY/year and LCC is lowest at 863,300CNY. The lowest heating costs among the three systems are at 760CNY/kJ.