Decision support for retrofitting building envelopes using multi-objective optimization under uncertainties

Abstract In the last decade, retrofitting strategies have been reviewed to improve energy efficiency and reduce environmental impact of existing buildings. One retrofitting strategy consists of innovating building envelopes into high-performance materials or systems. Despite the potential performance enhancement, opportunities for new envelopes have been constrained because various envelope options are difficult to be evaluated synthetically. Also, the decisions should consider the optimization of multiple objectives as well as uncertainties. In this respect, this paper aims to support the decisions of selecting building envelopes to meet multiple objectives under uncertainties while considering possible envelope options. A multi-objective optimization model is developed considering the existing built form, uncertainties in performance predictions, and incorporating newly developed facade systems. The optimal selections including emerging materials and technologies that are provided with building envelope renovation options to satisfy indoor thermal comfort, energy balance, environmental emissions, and economic aspects. The decision-support framework is also devised to add any envelope options. This adaptable framework enables decision-makers to accommodate new system materials and proactively evaluate their feasibility. The optimization model and framework proposed in this research will contribute to providing a roadmap for transforming existing buildings into smart and sustainable built systems.