Effect of Solar Radiation on Thermal Comfort in Inner Ambient Behind a Building Wall with Facing Material of Different Colors.

Document Type : Research Studies

Author

Assistant Professor at Faculty of Engineering., Architectural Engineering Department., Sohag University.

Abstract

This paper is aimed at investigating the effect of solar radiation on the inner ambient behind a building wall with facing material of different colors. At the wall outer-surface,  the incident radiation results in a reflected radiation into the outer ambient depending on the reflection-coefficient of the wall-facing material and a transmitted radiation in the wall, whose intensity decays through its propagation in the wall depending on the absorption-factor of the wall material. At the wall inner-surface, the transmitted-radiation results in a reflected-radiation inside the wall and a penetrated-radiation into the inner- ambient of the wall. The sequence of radiation-propagation is continued with incidence, reflection and penetration at the wall inner-surface as well as incidence and reflection at the wall outer-surface.. To the author's knowledge, this sequence of radiation-propagation is evaluated numerically -for the first time- in the present paper. The absorbed-radiation intensity in the wall and the penetrated-radiation intensity into inner-ambient are calculated for varying albedo-values according to color of the facing-material and different values of absorption-coefficient of the wall material. The proposed method justifies that the wall-facing materials with white color realize heat-protection in summer and heat-insulation in winter with a subsequent improvement of the thermal comfort. The temperature of the inner-ambient with facing-material of dark-color is higher than that with white-color in agreement with previous findings based on measurements for small-scale building walls by others and measurements by the author for local buildings in Assiut city, Egypt as well as predictions using computer software packages.

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