A Framework for Performance-Based Facade Design: Approach for Multi-Objective and Automated Simulation and Optimization

Buildings have a considerable impact on the environment, and it is crucial to consider environmental and energy performance in building design. In this regard, decision-makers are required to establish an optimal solution, considering multi-objective problems that are usually competitive and nonlinear, such as energy consumption, financial costs, environmental performance, occupant comfort, etc. Sustainable building design requires considerations of a large number of design variables and multiple, often conflicting objectives, such as the initial construction cost, energy cost, energy consumption and occupant satisfaction. One approach to address these issues is the use of building performance simulations and optimization methods. This paper presents a novel method for improving building facade performance, taking into consideration occupant comfort, energy consumption and energy costs. The paper discusses development of a framework, which is based on multi-objective optimization and uses the genetic algorithm in combination with building performance simulations. The framework utilizes EnergyPlus simulation engine and Python programming to implement optimization algorithm analysis and decision support. The framework enhances the process of performance-based facade design, couples simulation and optimization packages, and provides flexible and fast supplement in facade design process by rapid generation of design alternatives. Introduction Buildings account for about 40% of the global energy consumption and contribute over 30% of the global carbon emissions [14]. Energy used in building sector for heating, cooling and lighting comprises up to 40% of the carbon emissions of developed countries [14]. A large proportion of this energy is used for meeting occupants’ thermal comfort in buildings, followed by lighting. The building facade forms a barrier between the exterior and interior environments, and has a crucial role in improving energy efficiency and building performance. Therefore, this research focuses on performance-based facade design, appropriate simulation and optimization tools and methods for design analysis and support. Building performance simulation (BPS) provides relevant design information by indicating potential (quantifiable) directions for design solutions. BPS tools and applications facilitate the process of design decisionmaking by providing quantifiable data about building performance. BPS tools are an integral part of the design process for energy efficient and high-performance buildings, since they help in investigating design options and assess the environmental and energy impacts of design decisions [1]. The important aspect is that simulation does not generate design solutions, instead, it supports designers by providing feedback on performance results of design scenarios. Optimization is a method for finding a best scenario with highest achievable performance under certain constraints and variables. There are different methods for optimization, requiring use of computational simulation to achieve optimal solution, or sometimes requiring analysis or experimental methods to optimize building performance without performing mathematical optimization. But in BPS context, the term optimization generally indicates an automated process that is entirely based on numerical simulation and mathematical optimization [13]. Integrating BPS and optimization methods can form a process for selecting optimal solutions from a set of available alternatives for a given design problem, according to a set of performance criteria. This paper first focuses on identifying the role of BPS and design optimization methods, and outlines potential challenges and obstacles in performance-based facade design. This part is primarily based on literature reviews. Then, a new framework for performance-based facade design is presented. This framework takes into account occupant comfort and energy cost optimality, and implements BPS and relevant optimization methods to achieve a proper process for performance-based facade design. The components and development of the framework are discussed in detail. The last part of the paper offers conclusions and presents steps for testing and validating this framework.