Energy performance of office buildings in different climate zones in China
Student thesis: Doctoral Thesis
Buildings, energy and the environment are key issues that the building professions and energy policy makers have to address, especially in the area of sustainable development. The primary aim of this study is to develop the systematic methods for assessing and evaluating the influences of the diverse climate conditions on the thermal and energy performance of office buildings in major cities with different climates in China. Measured long-term hourly and daily weather data for the five major cities in China, namely Harbin, Beijing, Shanghai, Kunming and Hong Kong were gathered and analysed. These cities were selected to represent the five main architectural climates-severe cold, cold, hot summer and cold winter, mild, and hot summer and warm winter. The characteristics and features of the five major climatic types in China were examined by analyzing the long-term weather data through statistical techniques and graphical methods. Three common climatic variables, namely temperature (dry-bulb and wet-bulb), solar radiation (global, direct and diffuse) and wind conditions (wind speed and wind direction), were investigated. The frequency of occurrence and cumulative frequency distributions were determined and presented. Comprehensive typical meteorological years (TMYs) for the five cities were developed using long-term measured weather data, such as dry bulb and dew point temperatures, wind speed and global solar radiation. Generic buildings typical of the prevailing architectural designs and construction practices and meeting the requirements of the local building energy codes for the five cities were constructed. Hourly energy simulations for the five generic office buildings were conducted using the energy simulation program DOE2.1E to assess the thermal and energy performance of office buildings. The computed simulation results were analysed and compared in three main aspects - heating loads, cooling loads and the corresponding building energy consumption. To ascertain whether the TMY predicted thermal and energy performances followed long-term mean predictions based on multi-year weather data, energy simulated results from TMY were used to compare with those from individual years and their long-term means. Predicted monthly load and energy consumption profiles from TMY tended to follow the long-term mean quite closely. Parametric and sensitivity analysis was carried out to examine the importance of building input parameters. Thirteen key design parameters (in terms of their influences on building energy consumption) were identified. Changes in lighting load density affect not only energy use for electric lighting, but also energy requirements for space heating and cooling. Interactions between lighting load and heating and cooling energy use among the five cities were investigated. The heating influence coefficient varied from 0.08 in Hong Kong to 0.45 in Harbin, and the cooling influence coefficient from 2.09 in Harbin to 2.4 in Hong Kong. The north zone tended to have the largest influence coefficient for heating and vice versa. To characterize the interactions between different energy end-uses among the five cities, heating and cooling coincidence factors were also determined. The analysis results can help building designers and engineers identify key design variables and focus on building schemes that matter most.
- Office buildings, Energy conservation, Climatic factors, China