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Article Excerpt
Abstract: Local climate is a critical element in the design of energy efficient buildings. In this paper, ten years of historical weather data in Australia's eight capital cities were profiled and analysed to characterize the variations of climatic variables in Australia. The method of descriptive statistics was employed. Either the pattern of cumulative distribution and/or the profile of percentage distribution are presented. It was found that although weather variables vary with different locations, there is often a good, nearly linear relation between a weather variable and its cumulative percentage for the majority of middle part of the cumulative curves. By comparing the slopes of these distribution profiles, it may be possible to determine the relative range of changes of the particular weather variables for a given city. The implications of these distribution profiles of key weather variables on energy efficient building design are also discussed.
Keywords: Climatic data, Energy efficient buildings, Weather
Introduction
Any architectural realization concretizes a microcosm in more or less close connection with the environment to which it belongs (Gratia & De Herde, 2003). The goal of the design, renovation and construction of a building is therefore to achieve a microcosm in optimal agreement with its environment. Local climate is a critical element in the building design. It tends to not only influence the shapes and forms of the local building designs but also dictate the types of environmental control required (Lam, Tsang, Yang & Li, 2005). The climate of a particular location is often described by the prevailing long-term weather conditions, including evolution of the sunshine and the temperatures, and mode of the winds and precipitations (Gratia & De Herde, 2003). The process of identifying, understanding and controlling the climatic influences at a building site is perhaps one of the most critical parts of effective building design (Hui, 1996).
For buildings in Australia, the design requirements usually vary from location to location. For instance, in a warm humid climate, building designs are often required to promote air movement. Streets and buildings are therefore designed to orient as much as possible to catch the breezes. A mix of building heights will also have a positive effect. By contrast, in a hot dry climate, protection from the intense sunshine becomes essential. In a temperate climate, the wind direction usually changes markedly with the seasons. Therefore, designing a building that blocks cold winter winds, but allowing cooling summer breezes is particularly important (Bureau of Meteorology, 1997).
In this paper, ten years of historical weather data in Australia are analyzed to characterize the variation profiles of local climatic variables. The method of descriptive statistics is employed to study the key weather variables contained in the weather database. Either the pattern of cumulative distribution and/or the profile of percentage distribution for ten years weather data will be used to illustrate graphically the similarities and differences of weather patterns between different study locations. In addition to the dry bulb temperature (DBT), the profiles of other key weather variables will also be studied, which include atmospheric pressure, wind speed and wind direction, air humidity, total cloud cover, and the total global solar irradiance on a horizontal plane. General distribution of weather variables will be profiled and compared between the different capital cities in Australia. Their implication in energy efficient building design will also be discussed.
Research Methodology
Study Locations
The Australian island continent features a wide range of climatic zones, from the tropical regions of the north, through the arid expanses of the interior, to the temperate regions of the south (Australian Bureau of Statistics, 2005). The majority of the country is hot and dry. The sea exerts little moderating influence beyond the coast, and the highland area is too small and too low to have more than local effect (ASA, 2005). Most of the population lives in the coastal cities.
In this paper, the eight capital cities in Australia, including Adelaide, Brisbane, Canberra, Darwin, Hobart, Melbourne, Perth and Sydney, have been chosen for the study. These capital cities represent Australia's wide climate conditions, including:
* Hot humid summer, warm winter (e.g., Darwin)
* Warm humid summer, mild winter (e.g., Brisbane)
* Warm temperate climate (e.g., Adelaide, Perth and Sydney)
* Mild temperate (e.g., Melbourne)
* Cool temperate climate (e.g., Canberra and Hobart)
Weather Database
The hourly weather database used in this study is summarized in Table 1. This historic climatic data is supplied by ACADS-BSG, which is a specialist consulting company based in Melbourne, Australia, and supplies weather data for building simulation to Australia, New Zealand, Hong Kong and Singapore. As shown in Table 1, only one set of weather data (i.e., identified by W.M.O index number) was selected for each city in this study. Since weather data measured at different types of meteorological offices in a city could be different, in this study, to be consistent, weather data continuously measured at Regional Meteorological Office (RO) was used. However, in the case that there is lack of RO data for a city (e.g., Brisbane), data measured from other type of meteorological office (i.e., Airport meteorological offices) have to be used instead.
The weather variables contained in the above Australian climatic database include the hourly records of the dry bulb temperature (DBT), humidity ratio, atmospheric pressure, wind speed and direction, cloud cover, global solar irradiance on a horizontal plane, diffuse solar irradiance on a horizontal plane and direct solar irradiance on a plane normal to the beam. Although there are three types of solar irradiance data provided in the weather database, only the global solar irradiance on horizontal plane has been used in the study...
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