Genetic Algorithm Applied to Multi-Criteria Selection of Thermal Insulation on Industrial Shed Roof

Abstract

The rational use of energy has motivated research on improving the energy efficiency of buildings, which are responsible for a large share of world consumption. A strategy to achieve this goal is the application of optimized thermal insulation on a building envelope to avoid thermal exchanges with the external environment, reducing the use of heating, ventilation and air-conditioning (HVAC) systems. In order to contribute to the best choice of insulation applied to an industrial shed roof, this study aims to provide an optimization tool to assist this process. Beyond the thermal comfort and cost of the insulation, some hygrothermic properties also have been analysed to obtain the best insulation option. To implement this optimization technique, several thermo-energetic simulations of an industrial shed were performed using the Domus software, applying 4 types of insulation material (polyurethane, expanded polystyrene, rockwool and glass wool) on the roof. Ten thicknesses ranging from 0.5 cm to 5 cm were considered, with the purpose of obtaining different thermal comfort indexes (PPD, predicted percentage dissatisfied). Posteriorly, the best insulation ranking has been obtained from the weights assigned to the parameters in the objective function, using the technique of the genetic algorithm (GA) applied to multi-criteria selection. The optimization results showed that polyurethane (PU) insulation, applied with a thickness of 1 cm was the best option for the roof, considering the building functional parameters, occupant metabolic activity, clothing insulation and climate conditions. On the other hand, when the Brazilian standard was utilized, rock wool (2 cm) was considered the best choice.Buildings 2019, 9, 238 2 of 12 play a crucial role in the thermal performance of the buildings. In this context, the choice of the best insulation is difficult due to the various parameters that should be analyzed such as performance, cost, uncertainties related to hygrothermal properties, sustainability issues, etc. In this line of research, Adamczyk and Dylewski [3] proposed a methodology for assessing the environmental and economic benefits of thermal insulation. The results indicated that this investment is beneficial for ecological and economic reasons. Soares et al. [4] provided a survey of the main methods to measure the thermal transmittance and thermal behavior of construction elements such as the insulation materials.In order to promote the most adequate choice, other scientific works found in the literature can also be cited. Firstly, a literature review on determining the optimal thickness of the thermal insulation material in a building envelope and its effect on energy consumption has been carried out by Kaynakli [5]. Kaynakli [6] also investigated some parameters that affect the optimal insulation thickness, such as inflation and discount rates, lifetime, energy costs, the heating/cooling loads, and the properties of the insulation material. The optimal thickness and payback period was determined through an econo...

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