Thermal behavior evaluation of ventilated roof under variable solar radiation

Bianco, Vincenzo; Diana, Alessandra; Manca, Oronzio; Nardini, Sergio

doi:10.18280/ijht.34s222

Cited by 9 publications

(2 citation statements)

References 18 publications

(18 reference statements)

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“…Numerical analyses were made to understand the consequence of variable solar radiation in summer and winter [4]; during specific day in summer [5] to evaluate the performance of pitched roof with tiled coverings in comparison with unventilated systems and the results show that wind plays an important role. Compared to the tiles, both numerical and experimental analysis [6] were done in order to investigate the properties and the impact that clay tile materials have on the thermal performance of a ventilated roof.…”

Section: Introductionmentioning

confidence: 99%

Thermal Evaluation of Natural Convection in a Ventilated Roof under Variable Climatic Condition

Buonomo¹,

Capasso²,

Manca³

et al. 2020

TI-IJES

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One of the European Directive priorities is represented by the improvement of "building performance requirements" and the development of new strategies for "very low energy buildings" thanks to it is possible to reduce the energy consumptions due to the heat flux transmitted through the envelope of buildings. This paper illustrates a numerical investigation on a system that made possible this goal, in the specific a prototypal ventilated roof for residential use, inclined of 15° respect to the horizontal plane and the results are compared with a configuration with an inclination of 30°. Due to geometric and thermal symmetry the system has been studied considering a single side of the pitched roof. The analysis is carried out on a two-dimensional model in air flow and the governing equations are given in terms of k-ε turbulence model. The investigation is performed to evaluate thermo fluid dynamic behaviors of the ventilated roof as a function of the different conditions applied on the top wall and the bottom wall of the roof in summer and winter regimes. The problem is solved by means of the commercial code Ansys-Fluent on a channel of 6 m of length. The comparison shows that the inclination of 30° is more convenient both in summer and in winter due to the higher mass flow rate inside the channel.

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Section: Introductionmentioning

confidence: 99%

Thermal Evaluation of Natural Convection in a Ventilated Roof under Variable Climatic Condition

Buonomo¹,

Capasso²,

Manca³

et al. 2020

TI-IJES

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“…A simplified ventilated roof was modelled with FLUENT in [13], showing that the heat fluxes can be reduced up to 50% during summer. Recently, the natural convection due to buoyancy forces in ventilated roofs was simulated in [14] as a function of solar radiation in different thermal conditions (summer and winter season). Buoyancy forces are demonstrated to be efficient in producing significant airflows in the channel.…”

Section: Introductionmentioning

confidence: 99%

On the heat transfer through roof tile coverings

Bottarelli¹,

Bortoloni²

2017

IJHT

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In hot climates, ventilated pitched roofs with tiled coverings reduce the heat transfer across the roof, due to the ventilated air layer between tiles and roofing underlay, which is formed by the arrangement of battens and counter-battens. This so-called Above Sheathing Ventilation (ASV), which depends on the air entering and leaving at the eaves, ridge and the gaps between the tiles, has been enhanced by increasing the roof air permeability by means of novel roof tile shapes. This study analyses the air permeability improvement of a novel tile and its effect on the heat transfer induced by an external heat source (e.g. solar radiation). A CFD model is used to simulate the fluid flow and heat transfer through the tiles, solving the steady-state incompressible fluid flow in a 3D domain by means of the standard k-ε model. A parametric study is conducted to analyse the variation in the air flow passing through the tile and the tile temperature for different incident air flow conditions. A significant increase in flow rate is observed with the novel tile, which produces a lower temperature of the tile and of the air flowing through the tiles. This would help dissipating the excess heat in summer.

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