In previous investigations (Zappavigna and Liberati, 2001 and 2004) the possibility of improving the heat exchange through the roof by moving air under or through the covering has been examined in various experimental sets. This experience showed that by making slots in coverings with insulating layers the thermal performance of the roof can be improved coupling a reduction of the solar load during the day and an increase of the heat discharge during the night. An experimental trial has been arranged in order to check the optimal solutions in realizing such structures (that is shape and dimensions of the slots and thickness of the insulating layer). Previously a theoretical model of the thermal functioning of the roof had been created based on a fluid-dynamic software and a parametric study was carried on in order to find out the best constructive criteria. Then the alternative solutions were tested in various experiments, by comparing the thermal performances obtained with different roof types covering two scale building models. The sheds had dimensions of 1 m x 6 m plan and height varying from 1m to 2 m. The walls and the floor were insulated with a 10 cm thick polyurethane layer and to simulate the animal heat an electric source was disposed on the floor. The surface temperatures of the coverings were measured, as well as the internal and external air temperatures, the air speed through the slots, the solar radiation, the wind speed and direction. Some tests with smoke generators were also made to visualise the air movements. The measured values were analysed and the different performances examined. The theoretical model was then implemented and some hypotheses on the results obtainable in the real farming conditions (varying animals, building type and climate) were finally pointed out.

Slotted roofs as a tool for improving the housing conditions in hot climate

ZAPPAVIGNA, PAOLO;LIBERATI, PAOLO
2005

Abstract

In previous investigations (Zappavigna and Liberati, 2001 and 2004) the possibility of improving the heat exchange through the roof by moving air under or through the covering has been examined in various experimental sets. This experience showed that by making slots in coverings with insulating layers the thermal performance of the roof can be improved coupling a reduction of the solar load during the day and an increase of the heat discharge during the night. An experimental trial has been arranged in order to check the optimal solutions in realizing such structures (that is shape and dimensions of the slots and thickness of the insulating layer). Previously a theoretical model of the thermal functioning of the roof had been created based on a fluid-dynamic software and a parametric study was carried on in order to find out the best constructive criteria. Then the alternative solutions were tested in various experiments, by comparing the thermal performances obtained with different roof types covering two scale building models. The sheds had dimensions of 1 m x 6 m plan and height varying from 1m to 2 m. The walls and the floor were insulated with a 10 cm thick polyurethane layer and to simulate the animal heat an electric source was disposed on the floor. The surface temperatures of the coverings were measured, as well as the internal and external air temperatures, the air speed through the slots, the solar radiation, the wind speed and direction. Some tests with smoke generators were also made to visualise the air movements. The measured values were analysed and the different performances examined. The theoretical model was then implemented and some hypotheses on the results obtainable in the real farming conditions (varying animals, building type and climate) were finally pointed out.
Proceedings of the Seventh International Symposium on Livestock Environment
1
6
P.Zappavigna; P.Liberati
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11585/10028
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