Building energy-saving approach in early design stage

Abstract

Studies show that, decisions made in early design stage have great influences on building performance. Because in early design stage, building form nearly takes shape, and most of the parameters which can influence building performance are selected. For example, the sunshine hours, daylighting performance, natural ventilation, heating and cooling loads etc. With the promotion of the design process, the performance optimization possibility is smaller and smaller, and cost of the same benefit is higher and higher. Energy-saving optimization approach in view of office building in early design stage has been put forward in this research. The completed work includes that: the fast prediction algorithm of building energy consumption has been established and improved, because the previous algorithm is too simple, only applicable to rectangle buildings, and cannot satisfy architects’ higher requirements of architectural form’s complexity; and the algorithm has been developed in the aspects of building shape, daylighting analysis, TSC value computation and solar shadow analysis. Then, a forward process of calculation and a reverse process of optimization for energy-saving optimization in early design stage are put forward. In the part of case analysis, standard cases are designed to perform optimization of building form and function layout with the objective of a lowest total energy consumption, and parameter sensitivity analyze of the window-to-wall ratio, K value of wall, K value of window, SHGC of window and building exterior zone depth are performed. Four typical building forms are modelled to calculate and compare the shape coefficients and TSC values, then the optimization and analysis approach of single passive performance is introduced. Analysis results show that from Harbin to Guangzhou, building shape coefficient result shows a gradual increasing trend, which is in line with the common sense that building shape coefficient will increase from the north area to the south area in China. This result also verity the energy consumption prediction algorithm’s accuracy. And there is so little difference in thermal parameters between different schemes or the same scheme towards different orientations. From the sensitivity analysis results, influence of every parameter on the total energy consumption can be viewed. For some parameters, there even exists the optimal value which can make the lowest energy consumption. So, parameter sensitivity analysis can be regarded as important reference for decisions made in early design stage. Shape coefficient and TSC value show the same trend in representation of building thermal characteristics when building forms are common.