ENERGY PERFORMANCE OF LARGE BUILDINGS

Abstract

This project investigates and establishes a simplified dynamic energy analysis method, which is capable of rapid and accurate simulation of zone temperature fluctuation of a day as well as prediction of zone cooling load in commercial buildings. Our simplified method consists of two steps. The first step deals with establishment of the analytical solutions for the hourly zone temperatures and cooling loads, where the main assumption made is that the outdoor air temperature and humidity, the zone solar heat gains and the internal heat gams change with time sinusoidally. The second step deals with the calculation of correction factors for the hourly zone temperatures and cooling loads. The correction factors are derived by comparing the analytical results with DOE2.1E simulation results. In the part on zone temperature simulation, the coefficients and phase angles of the sinusoidal functions are calculated by using the DOE2.1E program m conjunction with a reference weather file for Singapore. Comparison between results obtained by the simplified model and the DOE-2 program shows good agreement in the zone temperature calculations. Their relative errors are within ± 3% on the average and ± 6 % at the maximum. In the part on zone cooling load prediction, results on zone cooling load calculated from the DOE-2 program and our simplified method are compared. With appropriate adjustments through the use of correction factors, it is shown that the difference is within ± 3 % on the average and ± 7 % at the maximum. This shows that the simplified energy analysis method offers a good alternative to the more involved and costly full-scale computer simulation using the DOE-2 code. In this project, a typical Singapore office building is used as a reference building. This simplified energy analysis method can be applied to commercial buildings operating under the tropical climatic conditions.