A multi-objective optimization model for building retrofit strategies using TRNSYS simulations, GenOpt and MATLAB

Promoting the cost effective improvement of the overall energy performance of buildings is among the main objectives of the Energy Performance of Buildings Directive (EPBD) of the European Union, being even emphasized in its recent recast. One of the best opportunities to achieve that aim is during building retrofit. In face of the multiple choices for retrofitting a building, the main issue is to identify those that prove to be the more effective and reliable in the long term. In this work, a simulation-based multi-objective optimization scheme (a combination of TRNSYS, GenOpt and a Tchebycheff optimization technique developed in MATLAB) is employed to optimize the retrofit cost, energy savings and thermal comfort of a residential building. A wide decision space is considered, including alternative materials for the external walls insulation, roof insulation, different window types, and installation of a solar collector in the existing building. A real-world case study is used to demonstrate the functionality of the proposed approach. The results verify the practicability of the approach and highlight potential problems that may arise.