Thermal analysis of vaulted roofs

Hadavand, Mahshid; Yaghoubi, M.; Emdad, Homayoun

doi:10.1016/j.enbuild.2007.02.024

Cited by 28 publications

(18 citation statements)

References 14 publications

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“…Other research has suggested that a vaulted roof with rim angles of less than 120 • at night and in the early morning (see Fig. 1) has a lower heat flow than a flat roof [43]. The same research pointed out that the efficiency increases with higher rim angles [43].…”

Section: Roof Shape and Formmentioning

confidence: 50%

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Reducing cooling demands in a hot dry climate: A simulation study for non-insulated passive cool roof thermal performance in residential buildings

Dabaieh

Wanas

Amer³

et al. 2015

Energy and Buildings

146

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a b s t r a c tIn hot dry climates, it is estimated that almost half the urban peak load of energy consumption is used to satisfy air-conditioning cooling demands in summer time. Since the urbanization rate in developing countries -like the case in Egypt -is rising rapidly, the pressure placed on energy resources to satisfy inhabitants' indoor comfort requirements is consequently increasing too. This paper introduces passive cool roof as a means of reducing energy cooling loads for satisfying human comfort requirements in a hot climate. A designed algorithmic hybrid matrix was used to simulate 37 roof design probabilities alternating roof shape, roof material and construction. The result of using a vault roof with high albedo coating shows a fall of 53% in discomfort hours and saves 826 kW h during the summer season compared to the base case of the conventional non insulated flat roof in a typical Cairo residential buildings. It is recommended that the selected cool roof solution be combined with natural ventilation to increase the indoor thermal comfort, and with passive heating strategies to compensate the increase in heating hours. The application is intended for low cost residential buildings in a hot dry climate.

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Section: Roof Shape and Formmentioning

confidence: 50%

“…1) has a lower heat flow than a flat roof [43]. The same research pointed out that the efficiency increases with higher rim angles [43]. In another study Tang et al recommend a half rim angle for vaulted roofs of between 50 • and 60 • to satisfy the needs of both un-air-conditioned and air-conditioned buildings.…”

Section: Roof Shape and Formmentioning

confidence: 95%

Reducing cooling demands in a hot dry climate: A simulation study for non-insulated passive cool roof thermal performance in residential buildings

Dabaieh

Wanas

Amer³

et al. 2015

Energy and Buildings

146

View full text Add to dashboard Cite

show abstract

“…A c c e p t e d M a n u s c r i p t This equation accounts for the beam radiation I beam , diffuse radiation received from the sky I diff 1 and that reflected by the ground I ref which is employed by Eqs. (7) to (9). ρ g is ground reflectance 2 coefficient and is assumed equal to 0.…”

Section: Introductionmentioning

confidence: 99%

“…is Stefan-Boltzmann constant and ɛ is surface 7 emittance and is assumed equal to 0.8 for thatch (Kahgel), which is the dome and windcatchers 8 coating [9]. 9…”

Section: Introductionmentioning

confidence: 99%

Thermal study of a cistern's dome (the case of Motamed cistern in Lar, Iran)

Najafi

Yaghoubi

2015

Energy and Buildings

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“…In most numerical studies, the surface heating, which was represented by a temperature difference between the surfaces and adjacent air, was prescribed as a constant value with time. A few studies incorporated radiation and heat transfer processes into numerical models to examine steady-state flow in the vicinity of buildings (Chen et al 2004;Hadavand et al 2008).…”

Section: Introductionmentioning

confidence: 99%

Computational Fluid Dynamics Modelling of the Diurnal Variation of Flow in a Street Canyon

Kwak

Baik

Lee

et al. 2011

Boundary-Layer Meteorol

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Urban surface and radiation processes are incorporated into a computational fluid dynamics (CFD) model to investigate the diurnal variation of flow in a street canyon with an aspect ratio of 1. The developed CFD model predicts surface and substrate temperatures of the roof, walls, and road. One-day simulations are performed with various ambient wind speeds of 2, 3, 4, 5, and 6 ms −1 , with the ambient wind perpendicular to the north-south oriented canyon. During the day, the largest maximum surface temperature for all surfaces is found at the road surface for an ambient wind speed of 3 m s −1 (56.0 • C). Two flow regimes are identified by the vortex configuration in the street canyon. Flow regime I is characterized by a primary vortex. Flow regime II is characterized by two counter-rotating vortices, which appears in the presence of strong downwind building-wall heating. Air temperature is relatively low near the downwind building wall in flow regime I and inside the upper vortex in flow regime II. In flow regime II, the upper vortex expands with increasing ambient wind speed, thus enlarging the extent of cool air within the canyon. The canyon wind speed in flow regime II is proportional to the ambient wind speed, but that in flow regime I is not. For weak ambient winds, the dependency of surface sensible heat flux on the ambient wind speed is found to play an essential role in determining the relationship between canyon wind speed and ambient wind speed.

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Thermal analysis of vaulted roofs

Cited by 28 publications

References 14 publications

Reducing cooling demands in a hot dry climate: A simulation study for non-insulated passive cool roof thermal performance in residential buildings

Reducing cooling demands in a hot dry climate: A simulation study for non-insulated passive cool roof thermal performance in residential buildings

Thermal study of a cistern's dome (the case of Motamed cistern in Lar, Iran)

Computational Fluid Dynamics Modelling of the Diurnal Variation of Flow in a Street Canyon

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