Effects of roof configuration on natural ventilation for an isolated building

Abstract

Numerical analyses based on CFD steady RANS were conducted to investigate the effects of roof configuration on wind-induced natural ventilation for an isolated roofed building. Gable roof and saltbox roof building models were tested with 15˚, 25˚, 35˚ and 45˚ roof pitch in present study. The flow field information and flow characteristics were obtained from the contours and plots generated by CFD. In accordance to the increment of roof pitch, the turbulence kinetic energy and mean velocity ratio show vigorous response. The flow separated at the windward corner do not reattach onto the roof, thus induced higher velocity gradient and form a large vortex at the roof ridge. The vortices behind then building caused by the flow separation at the roof ridge extend along the mixing layer and spread up to the roof. The pressure differences mainly rely on the roof shapes. Greater pressure differences between the upstream, interior and downstream was observed in saltbox roof cases. This is due to the extended roof height which boosted the impinging effect caused by the incoming wind. Generally, the saltbox roof configuration exhibit better performance than gable roof in terms of the measured parameters.

Low-Cost Apartment Design with Tropical Architecture Approach in Bekasi City

“…The roof's measure angles also determine its ability to provide natural air. The higher the roof's pitch, the better natural air it gets [15]. In this design, the roof angle is 30°, which increases the velocity on the indoor building [15].…”

“…Ventilation is a component that provides cool and natural fresh air from outdoor by expelling the hot and polluted air from indoor building [15]. Ventilation consists of two; passive ventilation and mechanical ventilation.…”

“…The higher the roof's pitch, the better natural air it gets [15]. In this design, the roof angle is 30°, which increases the velocity on the indoor building [15]. The roof provides space for air circulation and expels hot air through the louvers (see Figure 9).…”

Effect of gable roof with various roof pitches and obstacle heights on natural ventilation performance for an isolated building

“…It provides a highly effective and ecological passive cooling mechanism by introducing clean fresh air into a space [2,3]. A properly designed roof configuration is one of the major factors that contribute to the energy efficiency in buildings as it accounts for up to 50% of a building's solar energy gain [4]. Roof configuration also has significant impact on the wind flow pattern around and within a building [5][6][7].…”

“…Moey et al conducted a numerical study to investigate the ventilation performance of an isolated building with a gable roof and various roof pitches namely 15°, 25° & 35°. The numerical results showed the ventilation rate inside the building increases with the increment in roof pitches [11]. Zhou et al [9] analysed the impact of gable roof inclination on snow distribution with a series of two-dimensional CFD simulations and wind tunnel experiments.…”