Influence of window area and thermal transmittance in the consumption of electric energy in mid-western Brazil

The opening of windows allows the entrance of natural light, however, allows the transfer of thermal load from inside to outside the building and vice versa. Currently, despite the technological advances, it is still not possible in many buildings to integrate natural and artificial light. The design of a building, its geometry, size and properly orientation of the openings can result in great energy savings. Hence, defining the ideal window area for an ambient in which there is a balance between solar thermal load, air conditioning and natural and artificial lighting would lead to an environment whereby the energy consumption is optimized. This research presents the already consolidated methodology for calculation of ideal window area, which aims at the lower consumption of artificial lighting and air conditioning, considering a residential living environment. The analysis of energy consumption was carried out using the DesignBuilder software and the climate file of the city of Cuiabá - MT was considered, in order to quantify the impact of the climate on the supply of natural light and energy consumption. The methodology was divided into 3 stages, the first one consists of the determination of the base case and the constitution of the types of materials for analysis of the different thermal transmittance. In the second part of the method the simulations were performed and in the last stage the results were analysed. The simulations were performed considering the opening area at each 10% of the facade, for three geometries (1: 2, 1: 1 and 2: 1) considering three construction systems. The results showed that the openings in the south facade consume less and that this orientation allows larger openings, as well as the use of geometries with greater depth. Also, the thermal properties of the envelope influence the ideal window area, and the larger the thermal capacity the larger the openings that can be used. The present research showed the importance of considering the adequate areas and implementation of windows in the projects through the simulation. The potential of using sunlight for lighting has also been proven, by integrating natural and artificial light.