2011 Annual Report 1a.Objectives (from AD-416) The objectives of this research are to evaluate energy usage patterns in modern broiler housing throughout the production cycle and to determine the effects of energy saving measures on thermal conditions and production efficiency in broiler chickens during the brooding phase. 1b.Approach (from AD-416) Effects of reduced energy usage regimens and measures to improve energy efficiency in modern broiler housing on the thermal environment and subsequent production efficiency will be evaluated. 3.Progress Report Supplemental heat is required during the production cycle of commercial broilers; however, as growers rely on the attic for a source of supplemental heat, maximizing the energy available from pre-heated air is essential. To this end, a computational fluid dynamics model was developed to simulate airflow in a commercial broiler house attic during minimum ventilation cycles. The model showed that the bulk of the air coming from the attic flows directly from the roof ridge vent into the ceiling inlet, while entraining a modest amount of heated air. Efforts to improve attic inlet design are underway and will result in increased warm air pulled from the attic space as compared to the manner in which current systems operate. Progress is being monitored by weekly visits to the research facility, telephone calls and via e-mail correspondence.