Thermal comfort in rural buildings with green roofs

In Brazil, human comfort problems are due to the interaction of the tropical climate with the environment, which results in direct effects on loss of production and work efficiency. The objective of this research was to evaluate the level of thermal comfort in reduced and distorted models of rural buildings submitted to the green roofs. The research was conducted in the experimental field of the agricultural engineering department at UFRPE in the city of Recife, Pernambuco (Brazil) from April 1 to May 31, 2015. The roofs were made up of chanana green roof (Turnera subulata) (TVc), daisy green roof (Sphagneticola trilobata) (TVm), parsley green roof (Ipomoea asarifolia) (TVs) and fiber cement tile (Tfib). The internal meteorological variables of the air temperature (°C) and relative air humidity (%) were recorded through HOBO^® mini-dataloggers. The meteorological data from the external environment were recorded using an automatic meteorological station connected to a Campbell^® Datalogger (model CR1000). For thermal analysis of the reduced models roof, we used thermal images, obtained by a FLIR^® thermographic camera (model I60), in the inner surface of the roofs. The index of discomfort (ID), effective temperature (ET) and the human comfort index (HCI) were determined. The experimental design was completely randomized with four replicates and analysis; the comfort indexes were compared by the Tukey test (p<0.05). The green roofs TVc, TVm and TVs promoted the reduction of the internal air temperature with a reduction of the models in 0.71, 0.19 and 0.35°C, and the internal surface temperature at 1.5, 0.8 and 0.8°C, respectively, compared to Tfib. The reduced models submitted to the chanana green roof presented better indexes of thermal comfort and greater reduction of the internal air temperature.