Heat balance for two commercial broiler barns with solar preheated ventilation air

In temperate climatic zones, solar air heaters can reduce heating loads, and increase winter ventilation rates thereby improving inside air quality and livestock performance without additional fuel input. A heat balance was carried out to measure bird heat production under field conditions on two commercial broiler barns to evaluate the impact of solar heated ventilation air on bird performance, and identify strategies to reduce winter heating load. Located 40 km east of Montreal, Canada, the experimental broiler barns were identically built with three floors housing 6500 birds per floor in an all-in all-out fashion. Equipped with solar air pre-heaters over their fresh air inlets, the barns were instrumented to monitor inlet, inside and outside air conditions, ventilation rate and heating system operating time. The effects on bird performance were observed from November 2007 to March 2009 by alternating their operation between the barns. The measured sensible and total heat productions of 4.5 W and 8.4 W, respectively, for 1 kg birds corresponded to laboratory measured values. Bird performance was not affected by the solar air pre-heaters which increased the ventilation rate above normal during only 20% of the daytime period. Room air temperature stratification resulted in 20–40 kW of heat losses during the winter, representing 25% of the total natural gas heat load. Because inside air moved directly to the fans, large and rapid increases in ventilation inlet air temperature, produced by the solar air pre-heaters, resulted in further heat losses equivalent to 15% of the solar energy recovered. Sustainable energy management in livestock barns requiring heating should incorporate an air mixing system to eliminate air temperature stratification and improve fan flows.