To predict the performance of a naturally ventilated building, estimates of the windinduced surface pressure distribution are needed. In urban environments, where buildings are grouped closely together, these surface pressures will be strongly influenced by the surrounding structures. In addition, the sheltering effect of the surrounding built-up environment can make it more difficult to obtain large enough pressure differences across a building necessary to produce adequate natural ventilation air flow rates.
Three thermal analysis methods with different degrees of empiricism are quantitatively investigated regarding the ease of use, efficiency, accuracy and redundancy of generated information. From this investigation it is concluded that, for design purposes, a sensitive interplay between experiment and theory can often lead to an optimum method.
It was generally recognised that because of occupants' behaviour, natural ventilation rates were usually much lower than the accepted criteria for calculation. A great deal of anecdotal data existed which showed that frequency of opening windows bore a direct relation to external temperature and that the greater the volume the less the frequency of opening. The recent BRE survey also shows that very low ventilation rates, below 4 cubic metres/ person/hr have been found to be acceptable.
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