Performance of distributed energy systems in buildings in cooling dominated regions and the impacts of energy policies

The distributed energy system (DES) is an energy efficient and economical alternative to the centralized energy system (CES). However, quantitative performance assessment, the influential factors and the impacts of energy policies in cooling dominated regions are still not well studied. This paper therefore presents an investigation on the building integrated DES in Hong Kong, a typical city with cooling demand year-around. Considering the characteristics of the energy demands, DESs, which integrate distributed generations, chillers and the utility grid, are designed. The performance of DESs in buildings is tested on a simulation platform using dynamic models. The primary energy saving and the payback period are estimated. The impacts of major design parameters and energy policies on the DES performance are studied. Results show that DESs achieve energy saving only when integrated in large-scale buildings of certain functions. Moreover, the performance can be improved by optimizing the equipment capacities. The comparison between two different energy policies with respect to the grid interaction illustrates that DESs can achieve better performance when selling electricity is permitted. The gas price has very significant impacts on economic benefits of DESs and the current market gas price could allow cost-effective application in some circumstances.