An investigation of the impact of climate change on energy use in buildings in different climate zones across China
氣候變化在中國不同氣候區對建築能耗影響之探討
Student thesis: Doctoral Thesis
Author(s)
Detail(s)
Awarding Institution | |
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Award date | 15 Jul 2011 |
Link(s)
Permanent Link | https://scholars.cityu.edu.hk/en/theses/theses(33aeef48-db61-4917-86ed-a0901743b892).html |
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Other link(s) | Links |
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.
- Climatic factors, Buildings, China, Energy consumption