Abstract
Recently, many computer programs of dynamic air conditioning load have been developed and used in the calculation of cooling load. However, manual methods are used commonly for practical purposes. In this paper, we have chosen an office building as the model, which is ninestory high and a basement with a total floor area of 5,300m^2. The following three manual methods, which are widely used in Japan, were checked on and the cooling loads of the above model building were calculated by those methods. (A) Takasago Method (B) Conventional Method (Inoue's Method) (C) JSHASE Method The calculation by each of these methods is done by assuming that the outdoor condition changes periodically during a day on the basis of all-daylong air conditioning. Therefore, the heat gain through exterior walls and roof is calculated by E.T.D. (Equivalent Temperature Difference) method. However, on estimating solar heat gain through windows, the following difference appeared distinctly among the methods. In the method (A), the time-lag caused by heat storage in building structure, is not considered. On the other hand, in methods (B) and (C) consideration is given to the time-lag by Carrier's Storage Load Factor Method and Absorption Modification Factor Method, respectively. Finally, the results calculated by the above three methods were compared with the result by the JSHASE algorithm based on non-steady state analysis and the following conclusions were obtained. (1) The cooling load calculated by each of the three manual methods is effected significantly by the outdoor design condition. (2) If the same weather data are adopted, there are no noticeable differences among the cooling load obtained by the three manual methods. We proposed the "Pre-Cooling Load Factor" in the case of calculating pre-cooling load of intermittent air conditioning, and illustrated the mentioned factor for the various scales and structures of office building and at the various beginning times of air conditioning system operation.
