Numerical study of a cool roof and double-glazing window coupled to an air-cavity under a tropical Mexican climate

Abstract

This research presents a numerical study of the conjugate heat transfer in an air cavity with a concrete slab roof and a window on the east facade. We considered three different window configurations: a single clear glass window (C1), a double clear glass window (C2), and a double glass window with an inner clear glass and an outer reflective glass (C3), as well as three different types of roofs: gray roof, white roof, and black roof. Because both the conventional windows and roofs show high thermal energy gains that increase the energy dependence associated with using air conditioning equipment in buildings in tropical climates, we compared all cases regarding heat gains and temperature obtained under tropical weather conditions of Merida, Yucatan, Mexico. The results showed that WR is the option with the lowest temperature value at the inner surface of the roof (TR,in <39 °C). In addition, the C3-WR configuration reduced energy transmission through the facades by up to 5693.1 Wh, prevented the emission of 74.3 kg of CO2, and lowered electricity consumption costs by 13.2 USD/kWh compared to the C1-GR base case on the warmest day.

Keywords

• Double-glazing window
• Energy saving
• Passive cooling
• Conjugate heat transfer