Quantitative evaluation of the impact of building load characteristics on energy performance of district cooling systems

With the rapid increase of research and application of district cooling systems (DCS), the controversy whether DCS is really energy-efficient is intensifying. Building load characteristics of DCS may be a main reason for this controversy. However, how building load characteristics affect the energy performance and which load characteristics can ensure a high performance? To answer such critical questions and improve the energy performance of DCS, this paper presents a systematic method for quantitative analysis and evaluation of the impact of building load characteristics on the energy performance of DCS. Key energy performance indicators are proposed. The load characteristics of DCS are described and quantified by introducing the concept of Lorenz curve and Gini coefficient. "Grouping coefficient" is proposed to evaluate the rationality of grouping different buildings into the same branch of chilled water distribution system. Case studies are conducted to investigate the performance of DCS under different load characteristics and to compare with conventional cooling systems. The impact of Gini coefficient and grouping coefficient on the energy performance of chiller plant, chilled water distribution system and the whole DCS are analysed. Recommendations are provided for future's application of DCS and individual cooling systems.