UCSF collaborated with PG&E’s Savings Calculation Assistance program to optimize airflow in the Smith Cardiovascular Research Building (CVRB) on the UCSF campus in San Francisco, CA. CVRB is a research laboratory building that requires ventilation of outside air to comply with safety requirements. However this study determined that the building used higher airflow than necessary, and thus the building was not operating at maximum efficiency. UCSF evaluated more than 100 zones for Minimum Ventilation Setpoint, which is the minimum rate of outside air introduced into a specific building area. They found that many of the zones were receiving more outside air than needed, so they changed the building settings to reflect a lower air flow. After lowering the setpoints of the appropriate zones, UCSF achieved significant energy savings at CVRB.
Background
The CVRB HVAC system is comprised of rooftop air handling units (AHUs) delivering 100% outdoor air from the roof via variable-speed supply fans. Exhaust fans (EFs) on the roof remove exhaust air from the building, and a mix of variable-air-volume (VAV) and constant-air-volume (CAV) terminal units distribute hot and cold air to specific zones. These VAV and CAV units maintain temperature control with varying degrees of flexibility, which is dependent on the time of day and occupancy of the building. When the building is within the dead band range, it is operating at the minimum setpoint, and when it exceeds or decreases below the dead band, the cooling or heating is activated by the VAV terminals respectively. The dead band of a zone is wider when there are no building occupants and smaller during working hours. The building sources chilled water (CHW) and heating hot water (HHW) from a separate central plant.
Results
While it did not impact the electrical power demand (0 kW), the project resulted in substantial annual energy savings, both in electricity (104,298 kWh/yr) and in heating energy (47,198 therms/yr) which equates to 129.12 metric tons of carbon emissions and a calculated $194,064.
UCSF collaborated with PG&E’s Savings Calculation Assistance program to optimize airflow in the Smith Cardiovascular Research Building (CVRB)
