Development of a holistic performance approach for facade design

As a significant building sub-system, facade needs to be designed through the consideration of a wide range of factors. Facade design is given shape as a result of a collaborative work by stakeholders from different disciplines based on outdoor (environmental) and indoor (spatial) conditions, as well as project specific constraints, time/ budget limitations, legislation in order to fulfil functional, environmental and financial requirements of the project/users. Even just functionality related performance attributed to a facade is multifaceted such as structural, daylighting, or acoustic. Although, in literature there are researches focusing on different aspects of facade performance, there is a lack of a holistic point of view that considers different aspects at once. Aim of the paper is to present (a part of) a tool developed to be used during the facade design process and counts functional performance aspects altogether. The tool provides a holistic systematic approach in order to support the design optimization. It is intended to assist decision-makers while giving decisions on facade parameters (design variables) to consider their interactions with functional performance aspects in possible environmental and spatial conditions. The tool is in the form of spreadsheet designed via Microsoft Office software. The functional performance aspects included in the tool are structural, fire, water related, air permeability related, thermal, moisture related, daylighting,
and acoustic performances. The facade parameters defined as the main decision subjects within the tool are orientation, transparency ratio, facade type, window type, glazing, framing, shading, wall configuration, finishing, and detailing. First, for each facade parameter, design options are generated to keep the tool relatively simple and comprehensible. Then, matrices having design options in rows and performance aspects in columns are established. To support the decision-making, each intersecting cell in matrices proposes a rating or a rating prescription having conditional guidance. So, the tool user is expected to rate each option in terms of each performance in accordance with the prescriptions. The information provided in the tool is based upon an extensive literature review. The tool is composed of separate but interconnected rating charts designed for each facade parameter (the rating chart for orientation is presented in the paper). The overall facade performance is illustrated by a spiderweb graphic which has separate sections for each performance. Briefly, the tool is believed to enable the decision-makers to trace the consequences of their design decisions holistically, to give the decisions in a transparent way by highlighting the compromises in design, and to support the communication among stakeholders.