Lowest thermal transmittance of an external wall under budget,material and thickness restrictions: An integer linear programming approach

Abstract

[EN] This paper deals with the minimization of a building¿s external wall thermal transmittance, with theaim of improving the energy efficiency of the building. The wall¿s thermal transmittance must abide bythe current legislation, but also suit the limitations of other construction parameters, mainly budget andthickness, but also time limit, workforce, number and thickness of the layers and availability of materialsdepending on the approach.The optimization is achieved formulating an Integer Linear Programming (ILP) problem involving theparameters mentioned above. Therefore, any available ILP solver can be run to obtain the best combinationof the different materials and thicknesses for the layers, in order to minimize the thermal transmittance.This paper presents a case study of a common but representative external wall consisting of 6 layers,with more than 670,000 possible combinations of materials and their thicknesses. The study concludeswith a comparison of the lowest thermal transmittance obtained for a selection of budget and thicknesscombinations for the mentioned wall.