Decisão multicritério aplicada à otimização da envoltória de edificações residenciais de energia zero no Rio Grande do Sul

Abstract

The design and construction of Zero Energy Buildings can help reduce global energy consumption and, consequently, minimize environmental impacts. To design an energy-efficient building it is possible to use computational optimization tools, which will simulate sets of variables to find the best solutions. Faced with a variety of possible solutions, it is important to use a multi-criteria decision-making methodology to order them. The present study aims to determine the most suitable envelope configuration for obtaining residential Zero Energy Buildings in representative climate conditions of Rio Grande do Sul. Thus, the BEopt 2.8 software was used to obtain the optimal cases from the energy consumption and envelope costs point of view for Bioclimatic Zones 1, 2 and 3, in Rio Grande do Sul. Then, photovoltaic systems to balance the electrical energy consumption of each optimal case were determined. From this, the initial costs of the optimal cases were calculated, considering the cost of the envelope, the cost of the photovoltaic system and the other costs for the construction of the building. Furthermore, the adaptive model was used to assess thermal comfort indices of the optimal cases. Finally, four scenarios were considered to evaluate the optimal cases using the ELECTRE III multi-criteria decision-making process. Each scenario considered a different weight for each of the evaluation criteria (air conditioning consumption, initial cost, and thermal comfort index) to determine the best solution. The results show that in all scenarios, the best envelopes for Bioclimatic Zones 1, 2 and 3 have the main facade to the south, ceramic block walls (14 cm) and internal and external mortar (2.5 cm), 2 mm radiant barrier on the roof, percentage of transparent elements of 16% and distribution of these elements of 30% on the front and rear façades and 20% on the side façades. For the ZB1, as black exterior walls, a roof in dark colors, and windows with 3 mm single glazing are also indicated. In ZB2, the results show that pearl-colored walls, white roof, and the application of 3 mm glass characterize the best solution. On ZB3, we recommend pearl-colored walls, white roof, and 6 mm single glazed windows. In addition, it was possible to order the other optimal cases resulting from the optimization, facilitating the choice of the most adequate envelope configuration in face of possible restrictions. Thus, it was possible to verify that the results of the optimization process can be evaluated based on a set of criteria, assisting in decisions regarding the design of a residential Zero Energy Building.