Assessing the ventilation performance of a naturally ventilated livestock building with different eave opening conditions

In livestock housing permeable windbreak materials are regularly used at eave openings to reduce the adverse effects of windy outdoor conditions on the indoor environment. Two materials generally used for this application include space boarding, i.e. a traditional timber cladding system, and ventilated cladding, i.e. a profiled steel sheeting system with louvers cut into the protruding ribs. In this study computational fluid dynamics (CFD) models were developed to investigate the ventilation performance and thermal environment of naturally ventilated calf buildings with unrestricted, space boarding and ventilated cladding eave opening conditions. The effect of altering the eave opening height on both the indoor environment and ventilation characteristics of the building has also been investigated. It was found that ventilated cladding performed the best in terms of ventilation efficiency and thermal comfort during wind driven ventilation, as the high resistance of the opening condition prevented the short-circuiting of air from the windward to the leeward opening. For high porosity eave opening conditions, increasing the eave opening height was found to decrease the average air velocity at animal level due to a change in size and location of the primary air recirculation zone. It was also found that the resistance and the height of an eave opening determine whether or not the leeward eave opening acts as an air inlet.