Framework for Energy-Efficient Building Envelope Design Optimization Tool

Abstract

Multiple energy-simulation programs have recently been developed. Most of these programs utilize thermodynamic equations and the mechanical characteristics, loadings, and temperature set points of the building to predict the total energy demand in a year. In addition, numerous building design parameters, including building envelope, window-to-wall ratio, and building orientation and shape, influence the level of energy consumption, which makes the design process complicated. Challenges that manifest within these systems are inherently complex and interdisciplinary in nature, and they often defy linear, cause-and-effect correlation, which makes the simulation of building energy performance even more complicated. In addition to the difficulty of determining the best design parameters, multiple numbers of objectives, such as the life-cycle cost and environmental emission of the project, increase the complexity of the problem. Therefore, a proper multiobjective optimization algorithm tool that is capable of eliminating a portion of trial-and-error process is needed. This article presents a framework for developing a multiobjective design optimization tool that is capable of identifying the designs with the lowest life-cycle cost, lowest life-cycle emission, and highest occupant thermal satisfaction. To demonstrate the application of this framework, the development of the design optimization tool using a C# program is presented. The building envelope, as the major barrier between the outdoor environment and inside conditioned zone, was considered as the main building component to optimize. To calculate the occupants' thermal satisfaction, a predicted mean vote method (PMV) was used. Even though the theoretical basis behind this tool is robust and accurate, the developed tool is simple, flexible, and user-friendly to encourage its use among designers and engineers. It is expected that the developed tool will ease the integration of energy efficiency in commercial buildings.