Study On Method Of Evaluating The Energy Performance Of The Central Air-conditioning Water System In Public Buildings

In China, building energy consumption, industrial energy consumption andtransportation energy consumption have become three main bodies of energyconsumption. In building energy consumption, the central air conditioning systemoccupies a large proportion of it. It is one of controlled objects in building energyefficiency. In order to limit and decrease the air conditioning system energyconsumption, related departments have made a series of codes and standards. On onehand, it required controlling the loss of energy in buildings; on the other hand, itrequired developing efficiency of energy utilization. But so far, studying on properenergy utilization of air conditioning system in buildings mostly confines to the studyof a single device, which is inadequate to achieve the purpose of reducing the overallenergy consumption of air conditioning system. So the paper studies the publicbuilding energy efficiency evaluation of air conditioning water system to control thetotal building energy consumption.The paper is based on the existing energy efficiency assessment of airconditioning equipment and air conditioning system, proposes designing water systemenergy efficiency ratio (DWEER) and operation water system energy efficiency ratio（OWEER）to present air conditioning water system energy efficiency ratio indifferent stage. According to the definition of air-conditioning water energy efficiencyratio and energy consumption mathematical model for air conditioning equipment, itturns out that the main factors affecting operation of air conditioning water systemenergy efficiency ratio consists mainly of cooling water flow and temperature,freezing water flow and temperature, and load rate. Performance coefficient of chillerplant can restrain air conditioning water system energy efficiency ratio, and its size isclosely related to how much chiller plants energy consumption occupies the totalwater systems energy consumption. Based on an actual project, COP of chiller planthas strong correlation with system operation energy efficiency ratio. To a large extent,it can represent the level of energy consumption for the entire system.In order to confirm the relationship between the air conditioning water systemoperation energy efficiency ratio and influenced factors, the paper takes the sameproject as example, using the statistical software SPSS to build a multivariateregression equation and a multivariate quadratic regression equation based on multiple linear regression analysis model. Comparative analysis shows thatmultivariate regression equation is more reasonable to describe the relationshipbetween them. Through the partial correlation analysis, the paper ranks the impact offactors on air conditioning water system operation energy efficiency ratio.To building in different stage, the paper comes up with different energyefficiency evaluation method. Buildings in design stage and new used stage canevaluate efficiency level by comparing the reference value of DWEER and OWEER.Buildings in old used stage need evaluate air conditioning water system totalefficiency level firstly, then build current reference equation and evaluate energyefficiency under actual running condition. In the end, this paper evaluates an actualproject, the result shows this method can quickly evaluate the system energyefficiency and help to determine if the system needs to maintain or reconstruct.