An early-design stage assessment method based on constructibility for building performance evaluation

The goal of Zero Energy Buildings represents a challenge for designers: in order to meet required performance, a wide range of technologies and solutions is needed, and interactions with other stakeholders can limit productivity of building process. In this context, early-design stage plays a key role in building lifecycle: at this point, choices define design strategies, which strongly influence the following phases (developed design, construction and operational stages). In order to support decision making in early-design stage, we propose a new assessment method based on the French concept of constructibility, enabling designers to verify the relevancy and robustness of proposed solutions and process. Constructibility comes from buildability and constructability concepts, it sets some principles based on the anticipation of risks and considers both stakeholders' satisfactions and building performance issues. The evaluation is based on seven criteria: the simplicity of the solution, the verifiability, project skills availability, the simplicity to manage, the compliance with user-centric requirements, sustainability, and cost efficiency. Multi-criteria assessment employs Analytic Hierarchy Process technique to consider professional feedbacks about risks of performance changing. In the case study, a modular office south-oriented in Paris, the multi-criteria assessment is used to enable a decision-making support between various envelope solutions. The method enables to report project weakness and it represents a new practical tool enhancing constructibility.