Integrating requirement analysis and multi-objective optimization for office building energy retrofit strategies

• We present a model to support multi-criteria decisions for energy retrofitting.
• The model integrates requirement analysis and multi-objective optimization for design.
• The role of human reasoning on retrofitting optimization is emphasized.
• An office building in Germany needing an energy retrofit serves as a case study.

The existing office building stock is a key target for energy retrofits to substantially reduce adverse impacts on the environment, human health, and the economy. Success of an energy retrofit project is tied with the assessment and selection of energy efficiency measures that can satisfy stakeholders’ diverse, and often conflicting requirements. The current study establishes a model-based method to support design teams in making informed multi-criteria decisions for energy-efficiency solutions at the early design stage. The key feature of the hybrid framework is the integration of an analysis procedure carried out by a design team and a numerical procedure of optimization carried out by computer. Such an interaction is necessary as building design and retrofit requires many qualitative aspects that require human judgment. In contrast to previous approaches, this study provides a basis for embedding multi-objective optimization into the decision making on energy retrofit solutions, which considers the important role of stakeholders by carrying out the analysis procedure. An office building in Germany needing an energy retrofit serves as a case study to demonstrate the feasibility of the proposed model.