The Life Cycle Assessment Of Air-conditioning System

With the economic development, social progresses and the improvement of people's living standards of our country, the demand of air-conditioning increases sharply. However, the energy consumption of air-conditioning system is large, which takes up 60% of the entire building energy consumption in our country. Against the backdrop of energy conservation and emission reduction, it is essential to study how to reduce the energy consumption of air-conditioning system and achieve energy efficiency in buildings.Life Cycle Assessment originated in the 1960s as a new environmental management system, and after continuous enrichment, LCA has become an integrated system in term of environmental evaluation. The energy consumption of air-conditioning in different stages of the whole life cycle can be efficiently analyzed using this assessment system, which can provide an effective scheme for the energy saving design of air-conditioning systems.In this paper, a new evaluation model to analysis air-conditioning is created in the light of Life Cycle Assessment principles and frameworks. First, according to different research objectives and scopes, an air-conditioning system is divided into two parts, one part is air conditioner and the other is duct section. Then, the research range of the two parts is identified respectively. The research of air conditioner mainly focuses on the using stage, while that of duct section focuses on the obtaining process of raw material and processing production. The next step is to collect relative data in the air-conditioning system operation process, which are the data of energy consumption and emission in the unit using stage and the stages of raw material obtaining and manufacturing of ducts. Then the obtained data are arranged into an inventory analysis table. Finally, we can get different environment consumption values and environmental impacts potential values, and calculate the exhaustion of resources coefficient and environmental influence coefficient by classifying, characterizing and quantifying the inventory data.According the results of LCA, an optimization model of the design of air-conditioning systems is established using Analytic Hierarchy Process. This model is aimed at optimizing the design of air-conditioning systems, in which the criteria levels including four elements with reference to environment, resources, economy and technology and sub-criteria level including eight elements of environmental impact load, resource depletion coefficient and so on are established, and the weight of the elements in the criteria and sub-criteria levels is analyzed and a Analytic Hierarchy Process is obtained. Different air-conditioning designs are evaluated using the Analytic Hierarchy Process, and at last, the best design is chosen through comparing various designs.