Building facade multi-objective optimization for daylight and aesthetical perception

In recent years, especially in a building envelope, parametric design provides a method of continuous deformation of façade patterns until the architect finds interesting patterns or shapes that satisfy the desired aesthetics. However, these new design methods pose a question regarding the reasoning behind them, and sometimes the aesthetic interest dominates the true function of the envelope system and contrasts it. In opposite, too much engineering in the envelope system creates a problem with the identity of the façade. The purpose of this paper is to propose a method to integrate two different performances, quality and quantity, into one measurable goal. Using an existing building's facade as a case study, the building's facade was analyzed to understand the architect's logic behind its design. Then the found logic was programmed into the tool that allowed for the morphing of the façade into a different configuration, which can be evaluated by both quality and quantity performance to find the better solution to satisfy both goals. For the purpose of this paper, multi-objective evolutionary algorithms were considered to find solutions. For a quantitative objective, the indoor daylight availability was used as a measurement to allow for the best daylighting performance envelope system. For a qualitative objective, a matrix was developed to find the user's design preference and used it to evaluate and find a quantitative performance goal. The proposed method provides building facades that satisfy daylighting performance, and most importantly, it allows users to match their aesthetic sensibilities with the design preference.