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Title: An investigation of the impact of climate change on energy use in buildings in different climate zones across China
Other Titles: Qi hou bian hua zai Zhongguo bu tong qi hou qu dui jian zhu neng hao ying xiang zhi tan tao
Authors: Wan, Kok Wing ( 溫鉻穎)
Department: Department of Building and Construction
Degree: Doctor of Philosophy
Issue Date: 2011
Publisher: City University of Hong Kong
Subjects: Buildings -- Energy consumption -- China.
Energy consumption -- Climatic factors -- China.
Notes: CityU Call Number: TJ163.5.B84 W364 2011
xx, 312 leaves : ill. 30 cm.
Thesis (Ph.D.)--City University of Hong Kong, 2011.
Includes bibliographical references (leaves 245-268)
Type: thesis
Abstract: Recent reports by the Inter-governmental Panel on Climate Change (IPCC) have raised public concerns about energy use and the environmental implications. Buildings, energy and the environment are key issues facing the building professions and energy policy makers worldwide. The increases in the global temperatures exert pressure on building energy end-uses and have an impact on human being and the environment. The objective of this study is to investigate impact of climate change on the built environment in terms of human comfort and building energy consumption and mitigate the projected increase of energy use and carbon emissions in different climates across China. The scientific basis of climate change was outlined. It is generally acknowledged that the drivers of climate change were due mainly to the anthropogenic activities in raising the atmospheric concentrations of CO2, CH4 and N2O. A total of five cities in China - Harbin, Beijing, Shanghai, Kunming and Hong Kong were selected to represent the five major architectural climate zones: severe cold, cold, hot summer and cold winter, mild and hot summer and warm winter. Historical and future conditions of five climatic variables (minimum, maximum and mean dry-bulb temperatures, humidity and global solar radiation) during 1901-2100 were obtained from the CRU TS 2.1 data set and the WCRP CMIP3 multi-model database for two emission scenarios (low and medium forcing). Underlying trends of long-term summer and winter discomfort in terms of heat and cold stresses in different climate zones across China in the 20th (1901-2002) and 21st (2003-2100) centuries were investigated. A gradual shift from predominantly negative to positive comfort index was observed as one moved across the climate zones from the north to warmer climates in the south. For the severe cold and cold regions in the north, reductions in cumulative cold stress outweighed the increase in cumulative heat stress resulting in an overall decreasing trend in the annual cumulative stress, and vice versa for the other three warmer climate zones in the south. A reduction in cold stress would result in less winter heating and an increase in heat stress more cooling requirement. Principal component analysis of dry-bulb temperature, wet-bulb temperature and global solar radiation was considered to determine a new climatic index (principal component Z). Multi-year building energy simulations were conducted for five generic office buildings in Harbin, Beijing, Shanghai, Kunming and Hong Kong in different climatic zones in China. Regression models were developed to correlate the simulated monthly heating, cooling and total building energy use with the corresponding Z. The coefficient of determination (R2) varied between 0.77 and 0.99, indicating reasonably strong correlation. Future trends of heating and cooling energy consumption as well as total building energy use for the two scenarios (i.e. low and medium forcing) during 2001-2100 (2009-2100 for Hong Kong) were determined. A decreasing trend of energy use for heating and an increasing trend of energy for cooling due to climate change in future years were observed. For low forcing, the estimated reduction in heating was 22.3% in Harbin, 26.6% in Beijing, 55.7% in Shanghai, 13.8% in Kunming and 23.6% in Hong Kong; the increase in cooling energy 18.5% in Harbin, 20.4% in Beijing, 11.4% in Shanghai, 24.2% in Kunming and 14.1% in Hong Kong; and the overall impact on total building use -4.2% in Harbin, 0.8% in Beijing, 0.7% in Shanghai, 4.1% in Kunming and 4.3% in Hong Kong. Energy-efficient measures were considered to mitigate the impact of climate change on building energy use. Seven design variables that could have significant energy saving and CO2 reduction potentials were selected: wall U-value, window Uvalue, shading coefficient, window-to-wall ratio, summer set point temperature, lighting load density and chiller coefficient of performance. Raising the summer set point temperature by 1-2oC and lowering the lighting load density by 2 W/m2 could have great mitigation potential. It was found that there would be an overall increase in carbon emissions in all five cities, ranging from 0.5% in Harbin to 4.3% in Hong Kong for low forcing. There would be substantial reduction in the annual average carbon emissions in the 21st century if the cleaner fuel mix projected in 2020 was adopted: ranging from 4368 tCO2e to 2221 tCO2e in Hong Kong and from 6670 tCO2e to 4195 tCO2e in Beijing. These would represent about 37% reduction on the mainland and 49% in the Hong Kong SAR. Although this study was conducted for the five major architectural climates across China, it is envisaged that the approach could be applied to other locations with similar or different climates. Given the growing concerns about climate change and its likely impact on the built environment, this could have important energy and environmental implications.
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