ANALYSIS OF THE EFFECTS OF THE ROOFING DESIGN ON HEAT STRESS IN DAIRY COW HOUSING

In animal housing the roof plays a primary role in the determination of thermal exchanges of the animals. In particular, a high thermal resistance in daily hours can be helpful in a hot climate in order to reduce the effects of solar radiation. But an increased thermal resistance reduces the capacity of discharging heat through the roof in the night hours. In order to reduce the diurnal negative effect of the radiative heat load the use of insulating materials is normally recommended. But this is an expensive solution and its usefulness has not been confirmed, depending on various factors: climate, latitude, building geometry and orientation, constructive solutions, animal physical and spatial parameters. In dairy housing, many real buildings can be seen all over the world where the roof insulation is avoided and the reduction of the solar effect simply pursued throughout some geometrical parameters: slope, height, open ridge. This study aims at investigating the effective influence of the roof constructive parameters on the animal heat exchange (and welfare) during the whole day, trying to find out the optimal solutions for different combinations of the more relevant factors: insulation, slope, orientation, height, shape. The work, carried out by a specific theoretical model, is in this paper referred to a location in the North of Italy (Po valley), but it can be equally applied to other different climate and latitude conditions.