Investigation of multi-objective decision making approaches for the optimization in building envelope thermal design

• Decision making methodology considering the thermal design of a building. • Multi-objective optimization models were formulated based on Mathematical Programming. • Balancing conflicting criteria (economic, energy, environmental, thermal insulation) • Evaluation of different multi-objective optimization methods was conducted. • Compromise programming and Chebyshev goal programming fit the Pareto front. Improving the energy efficiency of building envelope components and technologies is of utmost importance, as it aligns with the crucial goals of providing carbon neutrality worldwide. This study presents a decision-making methodology for selecting thermal insulation materials and their thickness, as well as window frame materials, under the optimization of multiple criteria (economic, energy and environmental), giving a life cycle perspective too. Different Mathematical Programming models were formulated, examining the optimal solutions compared with the optimal Pareto solutions. The proposed method was implemented to a residential building considering different climate conditions of the Greek territory. Results of single-objective optimization show that a well-thermally protected building increases the economic, energy and environmental costs; for the case of climate zone A, an increase of 4.6, 2.8 and 8.3 times, compared to the optimal values of each criterion, is reported, while for the other climate zones the respective increase is lower. This highlights the importance of balancing the criteria, under a weighting sensitivity analysis. In the multi-objective optimization problem, compromise programming and Chebyshev goal programming are beneficial, reaching a percentage of 90 % for fitting the Pareto optimal results, in comparison to the global criterion and goal programming methods with a fitting of 13.5 %.