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Multistorey apartment living is becoming the preferred choice of housing in the Klang Valley area of Malaysia. This is due to economic and social reasons such as the increase in land prices in recent years. The ease of apartment living that usually comes with security and lifestyle packages (such as swimming pool and club house) is another factor that contributes to the increased demand for apartment type development. The method of construction for medium cost apartments is mostly based on reinforced concrete post and beam frame with brick infill internal and external walls with no thermal insulation and little shading. Most often no consideration is given to the solar orientation, resulting in bedrooms and living areas positioned on the western faςade which faces the hot afternoon sun. However some apartment blocks are built with courtyards and balconies that allow some degree of cross ventilation. Due to the hot and humid climatic conditions and their increased standard of living, occupants are installing air-conditioning systems in their apartments. This results in higher energy demand and is not a sustainable way of living into the future. This thesis explores the conditions of comfort, thermal and energy performance of residential units in multi-storey apartments using either air conditioning or natural ventilation. Low energy strategies (such as cooling techniques and design issues) that can be applied to this building type in order to reduce energy usage and thermal stress to the occupants are selected. Previous studies related to thermal conditions in the hot and humid climates are reviewed and analysed. Available simulation programmes are reviewed for suitability for this type of study. The validated simulation software used for this study is Tas. The neutrality temperature, comfort limits and energy requirements for simulating naturally ventilated and conditioned spaces for this climate are defined. The climatic data and typical building plans and location and zones are presented. The theory and process of simulation using Tas programme are described. Simulations are used to appraise the comfort conditions in these apartments using various configurations of the environmental and physical parameters. Simulations based on average day, hottest day, hottest month and one year are documented and analysed. The first sets of simulations for the conditioned and naturally ventilated spaces are based on existing conditions referred to as the "based case" studies. These spaces are uninsulated/unshaded and produced the worst results. Improvements are gradually superimposed on the base case in order to create better internal conditions. Results are processed to obtain Kelvin-hours (Kh re: 28.6°C) of overheating for naturally ventilated spaces and kWh cumulative load for air conditioned spaces. The results show that various low energy strategies i.e., natural ventilation through suitable opening schedules, shading, insulation, orientation, design layout, location of floors, materials, etc. could be used to reduce thermal stress and energy consumption. Based on average day simulation, the results indicate that comfort can be achieved using natural ventilation. For hottest day, comfort can be achieved with the aid of fans for most of the day. For air conditioned spaces, the energy used can be drastically reduced through the proper use of shading, insulation, orientation, higher set point temperature and material. The thermal design requirements for naturally ventilated and air conditioned spaces are discussed. Recommendations and guidelines for improved thermal comfort and energy efficiency in multistorey urban housing, based on the result of extensive simulations are proposed.
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