AVALIAÇÃO DA INFLUÊNCIA DA REFLETÂNCIA DO ENTORNO URBANO NO FLUXO DE RADIAÇÃO E NA CARGA TÉRMICA DE UMA EDIFICAÇÃO

Abstract

Cool materials present high solar reflectance and emission, which guarantee surfaces that absorb less solar radiation and dissipate through longwave radiation more quickly. The use of cool materials can contribute to reducing the energy consumption of buildings and as a strategy to mitigate heat islands formed in the urban environment. To evaluate the influence of the reflectance on the urban environment and the building itself on radiation flows and thermal load, computational simulations were performed using EnergyPlus version 9.3.0. From a simplified building model inserted in an urban canyon in Florianópolis, Santa Catarina, two scenarios were created with different soil reflectances and the building's walls and surroundings. The scenario with high reflectances, called the light scenario, presented higher values of incident solar radiation than the dark scenario due to the surroundings' reflection. Regarding the flow of longwave radiation on the building's facade, the dark scene showed greater sensitivity because associated with high absorptances, the surface temperature of the surroundings and the building itself also increases, stimulating heat exchanges by longwave. Finally, each scenario's total cooling and heating load was highly dependent on the building's orientation and the floor in question. In general, the dark scenario proved to be more economical concerning the sum of cooling and heating loads on the first two floors. On the last floor, the light scenario had a better performance. These relations are attributed to the amount of incident solar radiation on the facade.