Two-stage integer programing model for building retrofit planning for energy saving in South Korea

Due to the heightened concerns of global environmental problems caused by the heavy use of fossil fuels, the sharp increase of energy use in the building sector has been recognized as an important environmental issue. One solution for efficient energy consumption in the building sector is building retrofits. This study proposes a two-stage integer programing model to select building retrofit materials and retrofit planning. The first model is based on a multi-objective optimization that derives an optimal retrofit strategy considering both energy savings and retrofit costs. Using the results of the first model, the second model finds an optimal retrofit plan to minimize losses for the building owner. Based on a real general hospital building in Korea, a simplified case building was used to verify the proposed models and for experimental analyses. According to the results of the second model, the building owner could adopt a building retrofit with less than 30-40% of the initial budget when compared to the total retrofit costs.