Research On The Quantitative Analysis Method Of Centralized And Decentralized Issue In Building Service System

There are many discussions about whether the suitable building service system should be centralized or decentralized. In theory, the centralized building service system has many advantages. However, many real projects prove that the centralized building service systems usually cause high energy consumption or low system efficiency, which differ greatly from that during the design stage. The essential reason for these phenomenon is that the service objects in buildings are multiple independent terminal demands. When these demands change randomly and have strong characteristics of non-synchronism, the centralized building service system encounters great challenge to satisfy all the individual demands. Therefore, the characteristic of demand non-synchronization has important influence on the actual performance of building service system. In order to improve the building service system design and operation, it is important to take a close look at the main feature of demand non-synchronism and reveal its effect on the system performance. However, currently, there are lack of studies on the analysis about demand non-synchronism, and a further research on the quantitative description method of demand non-synchronization are in particular needed.In this study, a new methodology is applied to describe the non-synchronism characteristics of terminal demands in a graphic and quantitative way. The qualitative and quantitative demand non-synchronism can be reflected on the dimensions of time and space separately. Lorenz curve and Gini index, which are usually used in economic field to evaluate the uneven degree of resident income, are introduced in this study to describe the demand non-synchronism characteristics. According to the feature of buildings service system, some revision and adjustment are conducted on the index system to realize the quantitative description of demand non-synchronism characteristics. The index system is verified from the aspects of monotony, significance and consistency.Based on the quantitative description method, two typical regulating modes in building service system are discussed. In centralized regulating mode, the relationship between over-supply and demand non-synchronism is analyzed, and the quantitative principle is presented. For decentralized regulating mode, the influence of regulatory mechanism is studied. Further, through the analysis about the influence of demand non-synchronism on over-supply, distribution loss and cooling source efficiency in HVAC system, the interaction between demand non-synchronism and actual performance of building service system is revealed. Finally, the application of the index system in real projects are demonstrated to prove the effectiveness of the quantitative description method.The results show that the description method can turn the representation of building demands to quantitative index, which can evaluate the non-synchronism degree of building demand effectively. In this way, the influence of demand non-synchronism on the design and operation of building service system can be analyzed in a quantitative way. Based on the quantitative description method, more work of great significance can be carried out to promote the efforts on building energy saving in our country to reach a better future at the basis of real demand feature.