The envelope system is responsible for about 40% of the total energy consumption in a general building. Therefore, building envelope retrofit is an effective method to reduce the energy demand of buildings. In this paper, an optimization model for building envelope retrofit considering performance degradation is proposed to help decision makers to obtain an accurate optimal retrofit plan with a given budget, aiming at maximizing the energy savings and economic benefits. Specifically, the model determines the optimal retrofit options for the windows, walls, roof and a roof-top PV system from their alternatives. Considering that facilities will inevitably age over time, the performance degradation of the envelope components after retrofit is built into the model to ensure the accuracy of the optimal retrofit plan. A case study is carried out to demonstrate the feasibility and effectiveness of the proposed optimization model.
Keywords building envelope retrofit, roof-top PV system, multi-objective optimization, performance degradation, energy efficiency