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The implication of global warming on the energy performance and indoor thermal environment of air-conditioned office buildings in Australia

Guan, Li-Shan (2006) The implication of global warming on the energy performance and indoor thermal environment of air-conditioned office buildings in Australia. PhD thesis, Queensland University of Technology.

Abstract

Global warming induced by the emissions of greenhouse gases is one of the most important global environmental issues facing the world today. Using the building simulation techniques, this research investigates the interaction and relationship between global warming and built environment, particularly for the air-conditioned office buildings. The adaptation potential of various building designs is also evaluated.

Based on the descriptive statistics method, the Pearson Product Moment Correlation and the regression analysis method, ten years of historical hourly climatic data for Australia are first analyzed. The distribution patterns of key weather parameters between a Test Reference Year (TRY) and multiple years (MYs), and between relatively cold and hot years are also compared. The possible cross-correlation between several different weather variables are then assessed and established. These findings form a useful basis and provide insights for the development of future weather models under "hot" global warming conditions and the explanation of building performance at different locations.

Based on a review of the existing weather data generation models and findings from historic climatic data analysis, an effective method to generate approximate future hourly weather data suitable for the study of the impact of global warming is presented. This is achieved by imposing the future temperature projection from the global climate model on top of the historically observed weather data. Depending on the level of information available for the prediction of future weather conditions, this method allows either the method of retaining to current level, constant offset method or diurnal modelling method to be used. Therefore it represents a more comprehensive and holistic approach than previous one that have been used to convert the available weather data and climatic information to a format suitable for building simulation study. An example of the application of this method to the different global warming scenarios in Australia is also presented.

The performance of a representative office building is then examined in details under the five weather scenarios (present, 2030 Low, 2030 High, 2070 Low and 2070 High) and over all eight capital cities in Australia. The sample building used for this study is an air conditioned, square shape, ten storey office tower with a basement carpark, which is recommended by the Australian Building Codes Board to represent the typical office building found in the central business district (CBD) of the capital cities or major regional centres in Australia.

Through building computer simulations, the increased cooling loads imposed by potential global warming is quantified. The probable indoor temperature increases and overheating problems due to heat load exceeding the capacity of installed air-conditioning systems are also presented. It is shown that in terms of the whole building indoor thermal environment, existing buildings would generally be able to adapt to the increasing warming of the 2030 year Low and High scenarios projections and the 2070 year Low scenario projection. For the 2070 year High scenario, the study indicates that the existing office buildings in all capital cities will suffer from the overheating problem. To improve the building thermal comfort to an acceptable standard (ie, less than 5% of occupied hours having indoor temperature over 25°), a further increase of 4-10% of building cooling load is required.

The sensitivity of different office building zoning (i.e. zone at different floors and/or with different window orientation) to the potential global warming is also investigated. It is shown that for most cities, the ground floor, and the South or Core zone would be most sensitive to the external temperature change and has the highest tendency to having the overheating problem. By linking building energy use to CO2 emissions, the possible increase of CO2 emissions due to increased building energy use is also estimated.

The adaptation potential of different designs of building physical properties to global warming is then examined and compared. The parametric factors studied include the building insulation levels, window to wall ratio, window glass types, and internal load density. It is found that overall, an office building with a lower insulation level, smaller window to wall ratio and/or a glass type with lower shading coefficient, and lower internal load density will have the effect of lowering building cooling load and total energy use, and therefore have a better potential to adapt to the warming external climate. This phenomenon can be linked to the nature of internal-load dominated office-building characteristics. Based on these findings, a series of design and adaptation strategies have been proposed and evaluated.

Impact and interest:

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ID Code: 16329
Item Type: QUT Thesis (PhD)
Supervisor: Yang, Jun, Bell, John, & Sidwell, Anthony
Keywords: adaptation strategies, climate change, global warming, buildings, building performance, energy efficiency, indoor comfort, sustainable built environment
Divisions: Past > QUT Faculties & Divisions > Faculty of Built Environment and Engineering
Past > Schools > School of Urban Development
Department: Faculty of Built Environment and Engineering
Institution: Queensland University of Technology
Copyright Owner: Copyright Li-Shan Guan
Deposited On: 03 Dec 2008 14:01
Last Modified: 29 Oct 2011 05:46

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