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Premium Ventilation Proof of Concept Field Test

Premium Ventilation Proof of Concept Field Test. Reid Hart, PE Associate Director, Technical Research NPCC Regional Technical Forum October 13th, 2009. Premium Ventilation Package . Specifications Analysis Field Test Results. Beyond tune-ups & EER: Premium Ventilation Package.

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Premium Ventilation Proof of Concept Field Test

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  1. Premium Ventilation Proof of Concept Field Test • Reid Hart, PE • Associate Director, Technical Research • NPCC Regional Technical Forum • October 13th, 2009

  2. Premium Ventilation Package • SpecificationsAnalysisField Test Results

  3. Beyond tune-ups & EER:Premium Ventilation Package • Specifications: • Start with a Premium Economizer • Integrated with high or differential changeover • Upgrade the Economizer module with • DCV capable economizer control module • CO2 Sensor; Min air setting improved • Add variable speed fan motor control • Full (or near full) speed in heating or cooling • Low (40%) speed in idle mode • Field testing currently underway in Oregon

  4. Acknowlegements • Primary funding: • Bonneville Power Administration • Jack Callahan • Mira Vowles • With Support by: • Eugene Water & Electric Board • Will Price • Chris Wolgamott • Energy Trust of Oregon • Phil Degens • Nick O’Neil • NPCC Regional Technical Forum RTUG

  5. Single Phase Fan Speed Control forNew Units or Retrofit • Retrofit VSD Options • Two manufacturers now available ~ $250 • Both use temperature control strategy • Field testing discoveries: • Functioned well • Incompatible with “start-capacitor” motors

  6. Current acceptance testing is basically a sign-off California title 24 forms EWEB Premium Economizer checklist Improved forms will require field found values to be entered Designed to walk the contractor through the checkout and setup process Draft forms included in the report Need field testing during pilot Need streamlining Solid state controllers require a voltage generator during setup to properly adjust DCV setpoints Matching sensor range and output to the controller is non-trivial Better Acceptance Testing Needed

  7. Fan is in auto position During January, little daytime operation CO2 concentration almost triple desired After retrofit, highest CO2 concentration within target limits. Single return air sensor worked for multiple rooms: Computer lab Billiard room Significant Ventilation Improvements

  8. Easiest placement of the sensor is in the return air Concerns: Studies suggest putting sensor in the breathing zone (California T24 code required) When multiple rooms are served by one unit, an imbalance in ventilation quality may occur with uneven occupancy With VSD, less air throw at the diffuser may reduce ventilation effectiveness. Even with one room heavily occupied, return air sensing can meet requirements with a slight ventilation setpoint adjustment (900 ppm) Single CO2 Sensor Does It

  9. Premium Ventilation:Significant RTU Savings • Premium economizer savings, plus • Fan savings when not heating or cooling • Reduced ventilation when not occupied • Estimated HVAC savings: 25% - 45% • Compare savings in Sacramento, CA: • SEER 13 to 15: 0.22 kWh/sf • Premium Ventilation: 2.0 kWh/sf • Limited field testing: • One unit with adequate data shows double the savings • Waiting for post heating data to analyze others

  10. Premium Ventilation Package Regional HVAC Savings • Hart, et al. ACEEE, 2008

  11. Modeling Methods Reviewed • Four IPMVP “B” methods based on equipment electric measurement (vs. whole building) • Inverse model or change-point analysis • Hourly OAT average vs energy use • Daily OAT average vs energy use (NBI Proposed) • Multi-variable linear regression

  12. Works with full data set rather than averages 3-point model made the most sense without post heating data 5-point model expected to be more accurate once post heating data available Full year pre and post data recommended Inverse or Change Point ModelSupported by ASHRAE Research

  13. Hourly provides better overlap of pre and post data than daily Does not separate occupied vs. unoccupied; Will be separated in analysis after post-heating data is in Sufficient post heating data to establish conservative estimate of post heating model (unlike daily average) This unit shown has more than triple projected savings Additional savings from correcting improper unoccupied heat setting & achieving unintentional night flush effect Hourly Average by OAT Bin

  14. Heating separated from cooling Not enough post heating data R2 look good, as they often will for highly averaged data Shows significant Savings Current NBI Suggested Regional Approach – RTF/BPA buy in Daily Energy Signature

  15. Multi-Variable Regression • Select Variables • Both hourly and multi-day OAT • Co-determination shows importance • ECM & Occup • “Heating” indicator captures change point • Coefficients move as expected • Interactive variables move R2 from 0.19 to 0.45 • MV regressions are difficult to visualize

  16. The Importance of Occupancy • Average hourly data (HOD or hour of day) for pre and post period show distinct occupied & unoccupied energy uses • Requires modal (heat vs. cooling) analysis – more data points collected • What else is surprising?

  17. Period results Annualized results 2200 to 3600 kWh/ton Original projections 470 to 900 kWh/ton This particular unit had other savings contributors: Corrected daily heating surge at beginning of unoccupied period Continuous fan operation provided unwitting night flush effect in post period Conclusions Both signature approaches & change point line up fairly well with monitored After post-heating data is in, will run 2 units with occupied/unoccupied split Comparison of 4 Models

  18. Programs for the Brave – Next Steps • Go Digital Controls • Lab-testing based RTU expected value savings Evaluated Field Pilot

  19. Its time to let the low cost, 35 year old solid-state economizer controllers go. Just too many wires up on the roof. A combined programmable thermostat with BACnet DDC controller is now here at a reasonable price from multiple manufacturers. Its Time to Move from “Solid State” to Stand Alone Direct Digital Controllers

  20. Yes, 62.1 allows fan cycling General thinking: commercial fans must be ON during the occupied period Section 6.2.6.2 of ASHRAE Standard 62.1-2007 allows short-term interruption of ventilation if ventilation levels are maintained on average Continuous ventilation requires the fan switch to be “ON” during the occupied modes. Studies found close to 40% of thermostats have fan switch in the “Auto” mode resulting in intermittent fan operation and no ventilation control Advantages of DCV-IFC Interface with any staged rooftop unit with an economizer, With the fan off when not needed less damper leakage Greater savings than VSD power reduction at low speed Lower cost as no VSDs and associated wiring or motor upgrades are required. Higher reliability, as electronic (solid-state) controls are replaced with digital logic. Ventilation monitored and controlled Duty cycling would circulate air at least every 30 minutes DCV Integrated Fan Control (DCV-IFC)

  21. HVAC savings are not uniform like lighting If analyze sensitivity of savings to baseline parameter variation: Multiple load impacts Ventilation impact Fan operation impact Need to account for variation to find population savings for program The Retrofit is Uniform; Savings is Not

  22. The histogram of probability for different savings results based on the full range of baseline influences and combinations: There is a VERY WIDE spread of savings results Program-wide Savings Distribution

  23. Load based lab testing may be the answer In a few days in the lab: Dial in a range of weather conditions Dial in a range of load conditions Extrapolate results to different climates Breaking new ground Part of a current PIER RTU proposal Current ASHRAE research request to develop load based lab method Next phase for premium ventilation When the range of results is wide, to field verify program savings, either: Field test every installation, or Field test a very large sample in each climate Probably difficult to justify the cost of either field approach Field Testing for Measure Savings?

  24. Lab test to develop range of climate & load results Parametric simulation and expected value analysis to find programmatic retrofit savings Single expected value savings for contractor delivery Simulation finds sensitive parameters Field test to verify proof of concept Expected Value Savings Approach

  25. Next Steps • Wrap up premium ventilation long term report • Complete heating savings analysis • Field proof of concept testing of DCV-IFC • Upgrade to Digital Controls • Two flavors of premium ventilation • Variable speed drive during idle • DCV based fan cycling • Phase 2: Expected Value Savings Development • Simulation to pin down parameter sensitivities • Limited field testing to verify functionality • Lab testing to cover range of loads and weather • Expected value based projection of programmatic savings • Phase 3: Program Pilots with Evaluation – Next Summer

  26. Reid Hart, PE Associate Director, Technical Research 503-961-6142 rhart@peci.org

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