Comparison Of Commercial Buildings' Energy Consumption Pattern In China And Usa

This thesis focuses on the differences of commercial buildings'energy consumption pattern between China and USA and does the research on different perspectives, such as the characteristics of HVAC system, historical evolution of HVAC system, different cultural pursuit of the two countries and the indoor environmental comfort differences, etc. The goal of this paper is to find the root causes for the huge energy consumption differences between Chinese and American commercial buildings.Firstly, this paper made a thorough comparison and analysis of commercial buildings'energy data at three different levels: national level, campus level and typical buildings and made a conclusion that the difference of energy consumption between the two country's commercial buildings is huge. It also found the direct cause for the EC difference through simulation of a typical office building in US campus.Secondly, this thesis traced the evolution of HVAC system in the past century and discovered the rule that the Architectural form and HVAC system have been affecting each other ever since. Why VAV system prevails in US and why FCU system is only a supplement to VAV was also uncovered.Thirdly, it introduced the survey about the indoor environment comfort in the campuses in China and US and made a comparison of the thermal environment, lighting environment, acoustic environment, IAQ and general environment in the two country's campus buildings. The conclusion of the survey is: US spent several times higher energy consumption than China buildings but did not get the proportional indoor environment comfort. Comfort is more related to the physical parameters, such as temperature, luminance, etc and has little to do with energy consumption.Fourthly, the thesis dug to a deeper level and made the research about the quality of service of two country's buildings. It defined the concept of guarantee rate and found out the relationship between the guarantee rate and energy consumption with different service hours for VAV systems and the change of guarantee rate and energy consumption for VAV and FCU system when they have problems respectively. It proved that the reason why VAV system is preferred than FCU system in US is it has higher guarantee rate while the energy consumption can be accepted, which is in line with the situation in US: energy price is lower, cost for manpower is higher and users'satisfaction is highly sensitive.Finally, the thesis compared the total energy consumption and cooling load in cooling season between the systems: VAV, FCU+fresh air, FCU and Split air conditioner under different room occupation ratio. It pointed out that the influence of room occupation ratio on different system's energy consumption is different. When there are no people inside a room, the FCU or Split air conditioner in the room can be shut off while the fresh air handling unit can not be shut off and VAV box has to maintain a minimum supply. Therefore, the reduction of energy consumption of different system is different when occupation ratio drops. Different systems show different characteristics with different occupation ratio, so the random schedule of people and room should be considered in to the simulation to better reflect the real situation and get a right conclusion.