Presentation on theme: "Using Benchmarking to Identify Energy Efficiency Opportunity in Cleanrooms; The Labs 21 Approach William Tschudi and Peter Rumsey June 29, 2004"— Presentation transcript:
Using Benchmarking to Identify Energy Efficiency Opportunity in Cleanrooms; The Labs 21 Approach William Tschudi and Peter Rumsey June 29, 2004
Energy benchmarking Continuous process improvement is aided by observing actual energy use in operating cleanrooms. By studying the better performing systems, an engineer can debunk old myths and find innovative new solutions.
Energy benchmarking Building owners can compare performance against similar systems without regard to the process in the room.
Goal setting and benchmarking Facility and End Use “Energy Budgets” Efficiency Targets or Design Requirements for Key Systems and Components Cfm/KW KW/ton System resistance – i.e. Pressure drop Face velocities Etc.
System efficiency metrics vs. production metrics Compare HVAC systems regardless of process Focus on HVAC system’s efficiency Production metrics can mask inefficient systems
Cleanroom HVAC metrics Air systems – cfm/kW; cfm/ft 2 Recirculation Make-up Exhaust Cleanroom air changes – ACH/hr Re-circulated, filtered air Outside air (Make-up and Exhaust)
Cleanroom HVAC metrics Chilled water efficiency – kW/ton Chiller Tower condenser pump chilled water pump total chilled water plant
Recirculation air change rates and average velocities
Comparison of ISO Class 5 Cleanrooms
Recommended Air Change Rates – Various Sources
Improvement over ISO recommendations
Recirculation air change rates Studies confirm that air-change rates are often higher than is needed Benchmark data confirms that many achieve contamination control with lower air changes Since fan power is roughly proportional to the cube of the airflow, small reductions yield large energy savings Use of benchmark data and other studies can be used to set energy efficient air change rates Right Sizing Air Change Rates can result in lower construction costs and lower energy costs
Benchmark data reveals large variations in efficiency All energy in recirculation path (air movement and conditioning) needs to be included System pressure drop is key concern Air flow setback may achieve additional savings Efficient fans and motors can make a difference
Pressure drop is key Benchmark data illustrated that ducted HEPA filters (high pressure drops) were the worst performers
Make-up Air Opportunities Opportunities when higher than average CFM/kW is observed: Low face velocity/low pressure drop air handler Low pressure drop filtration strategy Run multiple makeup units in parallel Optimize exhaust air flow
Chilled Water Systems
Chilled water systems
Design Load vs Measured Load Design - Med Temp 39% Annual Average - Med. Temp 66%
Swing Chiller Concept Dual Temperature Chilled Water Plant
Chilled water systems Potential efficiency measures High-efficiency variable-speed drive chillers Low pumping energy schemes such as primary only variable speed pumping Efficient cooling towers with low approach temperature Optimized setpoints Free cooling Optimized setpoints Dual Temperature Chillers
Chilled water system choices Free Cooling Chiller Efficiency Variable Speed Chiller System Pressure drop Primary only or primary/secondary System controls Efficient Pumping Water vs. Air Cooled
DI water opportunity Variable speed drive RO pump Lower pressure drop RO membranes Variable speed drives on DI water recirculation pumps
Benefits of benchmarking Establish Baseline to Track Performance Over Time Prioritize Where to Apply Energy Efficiency Improvement Resources Identify Best Practices Identify Maintenance and Operational Problems Operational Cost Savings
Non-energy benefits of benchmarking Reliability Improvement Controls Setpoints Maintenance needs identified Leaks Motors, pumps, Fans Filters Chillers, boilers, etc. Safety issues uncovered Hazardous air flow
Conclusion Benchmarking Is Useful to Building Owners, Operators, and Designers Benchmark results can be used set performance targets and point to efficiency opportunities More Robust Data is Needed To Identify and Advance Best Practices “You Can’t Control What You don’t Measure” If You Have Benchmark Data – Share It!