Assessment of energy savings potential from the use of demand controlled ventilation in general office spaces in California

A prototypical office building meeting the prescriptive requirements of the 2008 California Building Energy Efficiency Standards (Title 24) was used in EnergyPlus simulations to calculate the energy savings potential of demand controlled ventilation (DCV) in five typical California climates per three design occupancy densities and two minimum ventilation rates. The assumed minimum ventilation rates in offices without DCV, based on two different measurement methods employed in a large survey, were 38 and 13 L/s per occupant. The results of the life cycle cost analysis show DCV is cost effective for office spaces if the typical minimum ventilation rate without DCV is 38 L/s per person, except at the low design occupancy of 10.8 people per 100 m2 in climate zones 3 (north coast) and 6 (south coast). DCV was not found to be cost effective if the typical minimum ventilation rate without DCV is 13 L/s per occupant, except at high design occupancy of 21.5 people per 100 m2 in climate zones 14 (desert) and 16 (mountains). Until the large uncertainties about the base case ventilation rates in offices without DCV are reduced, the case for requiring DCV in general office spaces will be a weak case. Under the Title 24 standard office occupant density of 10.8 people per 100 m2, DCV becomes cost effective when the base case minimum ventilation rate is greater than 42.5, 43.0, 24.0, 19.0, and 18.0 L/s per person for climate zones 3, 6, 12, 14, and 16, respectively.