4276 -- The Impact of Demand-Controlled and Economizer Ventilation trategies on Energy Use in Buildings PDF

The overall objective of this work was to evaluate typical energy requirements associated with alternative ventilation control strategies for constant-air-volume (CAV) systems in commercial buildings. The strategies included different combinations of economizer and demand-controlled ventilation, and energy analyses were performed for four typical building types, eight alternative ventilation systems, and twenty U.S. climates. Only single-zone buildings were considered so that simultaneous heating and cooling did not exist. The energy savings associated with economizer and demand-controlled ventilation strategies were found to be very significant for both heating and cooling. In general, the greatest savings in electrical usage for cooling with the addition of demand-controlled ventilation occur in situations where the opportunities for economizer cooling are less. This is true for warm and humid climates and for buildings that have relatively low internal gains (i.e., low occupant densities). As much as 20% savings in electrical energy for cooling were possible with demand-controlled ventilation. The savings in heating energy associated with demand-controlled ventilation were generally much larger but were strongly dependent upon the building type and occupancy schedule. Significantly greater savings were found for buildings with highly variable occupancy schedules and large internal gains (i.e., restaurants) as compared with office buildings. In some cases, the primary heating energy was virtually eliminated by demandcontrolled ventilation as compared with fixed ventilation rates. For both heating and cooling, the savings associated with demand-controlled ventilation are dependent on the fixed minimum ventilation rate of the base case at design conditions.

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