Kitchen exhaust hoods are a large energy consumer in cafeteria spaces. Significant amounts of energy can be conserved by utilizing transfer air – conditioned air from adjacent spaces – as replacement air, thus reducing the need for conditioned makeup air. Fan energy can also be saved by reducing air circulation when cooking activity is low. Demand ventilation systems (DVS) conserve energy by vary exhaust and makeup fan speeds in alignment with the demand of existing conditions. ANSI/ASHRAE/IES Standard 90.1 sets energy efficiency requirements for kitchen exhaust hoods.