San Diego State University (SDSU)
(Laboratory Airflow Controls System Engineering Review and Re-Commission):
The San Diego State University (SDSU) Chemical Sciences Laboratory Building (CSLB) is a 100,000 ft2 laboratory building completed in 2000. The building is served with chilled water and steam from a campus-wide central plant. The laboratory ventilation system consists of four (4) large (70,000 CFM) variable-air volume (VAV) air-handling units which deliver 100% outside (single pass) air to the building, and two large exhaust systems (each exhaust system has five fans). There are 174 fume hoods in the building. Not surprisingly the building is a large energy user.
The building has gone through several modifications since it was first constructed. However, it had not been re-commissioned since the modifications. With these recent changes and the high energy intensity of the building, it was an excellent candidate for re-commissioning under the UC/CSU/IOU Energy Efficiency Partnership’s Monitoring-Based Commissioning (MBCx) program.
Newmatic Engineering performed a thorough re-commissioning of the Laboratory Airflow Control System (LACS). Each device in the LACS was verified to be operating optimally in every conceivable sequence of operation. Most rooms were verified in four modes: hoods open, cooling; hoods open, heating; hoods closed, cooling; and hoods closed, heating. By operating each room in all four modes, we assured that each airflow device would be tested in its maximum and minimum position of operation.
In this process, Newmatic Engineering documented existing system operation. There were cases where system operation was deficient: it deviated from the desired sequence of operation. In most cases, these deficiencies caused excessive energy use. All deficiencies were noted in a Master List of Deficiencies and Potential Improvements (MLD&PI). After the deficiencies were noted, their associated energy penalty was recorded and corrective action was taken to restore proper system operation. There were over 100 deficiencies noted and corrected in the SDSU CSLB.
In the final analysis, we calculate the total annual energy cost saved by this re-commissioning effort is approximately $196,000.
Of this energy, about 80% is electrical, and 20% is natural gas. Assuming an electrical rate of $0.138/kW-hr and a gas cost of $0.50 per therm, the annual energy saved is 1,146,090 kW-hr and 75,679 therms. These calculations are in the process of being verified by a Measurement and Verification process.
Energy Cost Reduction = $180,000
Simple Payback Period < 1 Year
Baseline Energy Usage
- 3,125,000 kWh/year (building)
- 1,600,000 ton-hours cooling supplied by central chiller plant
- 17,000 MMBTU heating supplied by central steam plant
Post Re-Commission Energy Usage (as of February 2006)
- 2,715,000 kWh/year (building)
- 1,500,000 ton-hours cooling
- 13,500 MMBTU heating
Projected Chilled Water and Steam Savings Exceeded
(Current usage per most recent metered data)
- 1,120,000 ton-hours cooling
- 10,100 MMBTU heating