A thermal simulation model and suitable weather data were used to generate design curves for the application of night ventilation cooling to office buildings. The work was carried out under the programme of the International Energy Agency (IEA) Annex 28 on 'Low Energy Cooling'. The generated curves show the potential reduction in internal peak day temperatures throughout the cooling season, the free cooling provided by night ventilation and the number of hours that a fan would run during the night for mechanical systems to achieve this free cooling.
In recent years there has been a gradual re-emergence of the use of passive or 'low energy' ventilation and cooling techniques including mixed mode application. It is apparent that many clients developers and agents are reluctant to make a commitment to such 'low energy' buildings due to concerns, albeit unsubstantiated by hard evidence, that such buildings will provide acceptable comfort levels for occupants.
The purpose of the study was to measure the performance of natural ventilation in 5- and 9- storey apartment buildings, and to offer solutions for the improvement of ventilation. In the four most common building types, the functioning of the old ventilation system was measured during a spring and summer period. The economically feasible improvement solutions, as installing the auxiliary fans and mechanical exhaust ventilation, were analysed with measurements and calculations. The old natural ventilation system with stacks and leaky windows can maintain a certain basic level of ventilation.
In a room with a raised floor HV AC system (RF system), the vertical temperature gradient became an important factor in relation to the ventilation requ1rement to maintain a vertical temperature difference within a comfort standard such as ASHRAE Standard 55-1992. A series of detailed laboratory experiments were carried out to obtain the design ventilation requirements with various conditions of ventilation rates, cooling loads, and types of floor outlets. The main results are shown as follows.
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