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BPA RTU

BPA RTU. Rooftop Unit Pilot Servicing Program Monitoring Results Presentation to the RTF RTUG December 15, 2009 Kathryn Hile The Cadmus Group. Presentation Overview. Key program elements Savings algorithm Sample distribution Detailed findings Metered data PTHVAC tool FDSI tool

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BPA RTU

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  1. BPA RTU Rooftop Unit Pilot Servicing Program Monitoring Results Presentation to the RTF RTUG December 15, 2009 Kathryn Hile The Cadmus Group

  2. Presentation Overview • Key program elements • Savings algorithm • Sample distribution • Detailed findings • Metered data • PTHVAC tool • FDSI tool • Lessons learned and recommendations • Annual metering Emerging Energy Efficiency Technologies

  3. Key Program Elements • Pilot evaluation elements • Service protocols Emerging Energy Efficiency Technologies

  4. Key Pilot Evaluation Elements • Evaluation approach: • Measure cooling and fan energy use at individual RTU level • Larger sample size • Two week pre/post metering with annualization • Energy signature (kW and OA temperature) and TMY3 weather data to annualize cooling and fan energy savings • Compare metered savings to estimated savings Emerging Energy Efficiency Technologies

  5. Service Protocols • 2008 AirCare Plus pilot used the FDSI tool in theSpokane area and the PECI AirCare Plus training, protocols and quality control • 2009 Performance Tested HVAC pilot used the FDSI tool and the PSE Premium Service protocols in the Puget and Tri-Cities areas Emerging Energy Efficiency Technologies

  6. Premium Service Protocols • Each unit in the Puget Sound and Tri-Cities areas received a package of measures; basic diagnostic package (A): • Other packages: • B (basic diagnostics plus fix damper) • C (basic diagnostics plus new thermostat) • D (basic diagnostics plus new controller) Emerging Energy Efficiency Technologies

  7. Key Program Elements: Monitoring Goals • Measure electric energy savings from the monitored units • Analyze electric savings per RTU and per measure category, and compare ex ante to ex post savings • Report results and lessons learned to improve estimation, measurement, and realization of energy savings • Recommend improvements to direct BPA’s planned 2010 RTU servicing program Emerging Energy Efficiency Technologies

  8. Savings Algorithm • Monitored one-minute data Emerging Energy Efficiency Technologies

  9. Savings Algorithm • Aggregate into hourly averages and/or sums • Calculate hourly averages for: • Outside air temperature • Total unit power • Supply, mixed, and return air temperature • Calculate maximum hourly power • Use these values to examine data through output graphs: • Compressor power • Time series • Percent outside air • RTU operation • Energy signature Emerging Energy Efficiency Technologies

  10. Savings Algorithm • Energy signature: used with TMY3 data to annualize energy • Horizontal line = fan energy • Sloped line = fan + compressor energy • Balance point = intersection of horizontal and sloped lines Emerging Energy Efficiency Technologies

  11. Savings Algorithm • Calculation uncertainty: • Residual value: accurate to within ±0.03% • Balance point temperature: accurate within 2% • Annual metering: • Will confirm or better align our methodology with annual performance data • Sensitivity analysis: • Will be summarized in a white paper Emerging Energy Efficiency Technologies

  12. On-Site Data Collection • Two weeks baseline and post-servicing • One-minute data • Site characteristics recorded • On-site data collection • Basic metering package: • Total unit power • Outside air temperature/RH • Modified basic package: • Supply air temperature • Y-1 call for cooling • Full package: • Return air temperature • Supply air temperature • Mixed air temperature Emerging Energy Efficiency Technologies

  13. Sample Distribution for 161 Units • Climate zone • Building type • Tonnage • Servicing contractor • RTU type • Unit age Emerging Energy Efficiency Technologies

  14. Sample Distribution • By climate zone and metering package type Emerging Energy Efficiency Technologies

  15. Sample Distribution • By building type Emerging Energy Efficiency Technologies

  16. Sample Distribution • By cooling capacity and region Emerging Energy Efficiency Technologies

  17. Sample Distribution • By RTU type Emerging Energy Efficiency Technologies

  18. Detailed Findings • Metered data • PTHVAC estimates • FDSI estimates Emerging Energy Efficiency Technologies

  19. Metered Savings • Metered data savings: cooling and fan energy • 161 RTUs metered • 102 RTUs in Puget Sound, Tri-Cities and Spokane areas with completed post-servicing data • Average savings: 1,615 kWh per unit Emerging Energy Efficiency Technologies

  20. Metered Savings • Total cooling and fan energy savings Emerging Energy Efficiency Technologies

  21. Metered Savings • Total cooling and fan energy savings Emerging Energy Efficiency Technologies

  22. Metered Savings • Compressor and fan savings (kWh/ton) Emerging Energy Efficiency Technologies

  23. Metered Savings • Average savings by rated cooling capacity Emerging Energy Efficiency Technologies

  24. Metered Savings • Savings in kWh/ton for each RTU Emerging Energy Efficiency Technologies

  25. Metered Savings • Total cooling and fan energy savings for RTUs at least seven tons Emerging Energy Efficiency Technologies

  26. Metered Savings • Metered savings for 3- to 6-ton units Emerging Energy Efficiency Technologies

  27. Metered Savings • Average savings by servicing company Emerging Energy Efficiency Technologies

  28. Metered Savings • Average savings by unit age • Average savings by RTU type Emerging Energy Efficiency Technologies

  29. Metered Savings • Savings by existing servicing contract Emerging Energy Efficiency Technologies

  30. Service Measures • Thermostat measures • Replacement • Setpoint or schedule changes • Economizer measures • Economizer commissioning • Setpoint changes • Fixing dampers • Replacing or repairing broken parts • Minimum and maximum ventilation adjustment • Refrigeration cycle measures • Condenser coil cleaning • Evaporator coil cleaning • Refrigerant charge adjustment • System airflow adjustment Emerging Energy Efficiency Technologies

  31. Service Measures Savings • Ten RTUs with the greatest savings Emerging Energy Efficiency Technologies

  32. Service Measures Savings • Thermostat measures: operating schedules • Average savings for 30 RTUs: 3,307 kWh • Average savings 7 tons and greater: 5,198 kWh • All had positive savings • 83% of the units realized savings • Maximum savings: 15,408 kWh Emerging Energy Efficiency Technologies

  33. Service Measures Savings • Thermostat measures: operating schedules • Baseline conditions • 34% of units ran at least 95% of the time • Building types • Included banks, offices and small box retail • After servicing • Fan duty: • Decreased in only 10 of the units • Nine of 10 had significant savings • Banks: • Four RTUs did not change from 24-7 • Offices and small retail: • Six of 14 RTUs reduced their schedules Emerging Energy Efficiency Technologies

  34. Service Measures Savings • Economizer measures: economizer changeover temperature adjustment compared to change in percent compressor operation Emerging Energy Efficiency Technologies

  35. Service Measures Savings • Economizer measures: percent outside air in RTU0022 Emerging Energy Efficiency Technologies

  36. Service Measures Savings • Economizer measures: minimum ventilation adjustment • Correlation: • Cannot isolate effect of minimum ventilation increase • Code settings: • Proper settings were not provided to the technicians for each building type • Result: non-uniform changes for each building type • Measurement inaccuracy, calculation uncertainty: • Inaccuracies in onsite measurements • Difficulty of precision during adjustments • Uncertainty in the calculations Emerging Energy Efficiency Technologies

  37. Service Measures Savings • Refrigeration measures • Evaporator and condenser coil cleaning on RTU0169 Emerging Energy Efficiency Technologies

  38. Service Measures Savings • Refrigeration measures: refrigerant charge adjustment • No strong correlation to extreme savings • 10 units received RCA and economizer measures (thermostat measures removed) • Average savings: 1,954 kWh • Refrigeration measures: system airflow adjustment • Caused increase in fan power • Resulted in higher daily base load • Increased annual electric energy Emerging Energy Efficiency Technologies

  39. Service Measures Savings • Refrigeration measures: system airflow adjustment on RTU0034 Emerging Energy Efficiency Technologies

  40. Service Measures Savings • Refrigeration measures: system airflow adjustment • Units with thermostat measures are not shown Emerging Energy Efficiency Technologies

  41. Service Measures Savings • Little to no savings: • 55 out of 102 units showed savings of ± 1,000 kWh, an average savings of 3% • RTU size: 40 were less than 7 tons • PTHVAC package A for 38of the 46that received a PTHVAC package • Unit age: 1 to 24 years • Servicing measures: combination of all available measures Emerging Energy Efficiency Technologies

  42. PTHVAC Savings Calculator • Pilot-level savings • Savings by Premium Service package Emerging Energy Efficiency Technologies

  43. PTHVAC Savings Calculator • Estimated savings (kWh) for 145 RTUs • Average savings: 1,402 kWh • Median savings: 706 kWh Emerging Energy Efficiency Technologies

  44. FDSI Service Assistant Tool • FDSI default runtime and equivalent full load hours (EFLH) • Default EFLH: 1,200 hours • Default runtime for each compressor: • Compressor 1: 1,956 hours • Compressor 2: 1,452 hours • Compressor 3: 948 hours • Compressor 4: 444 hours Emerging Energy Efficiency Technologies

  45. Compressor Operation • EFLH and compressor runtime • Individual units changed in either direction • Overall, no change on average for the group • Change in EFLH for RTUs with one compressor: Emerging Energy Efficiency Technologies

  46. RTUs Monitored After the Cooling Season • By RTU type • Fan characteristics • Fan duty did not change in 9 of 10 units that ran 100% of the time before servicing • 6 units served spaces that did not operate overnight or on weekends • Fan power increased in most sites where system airflow adjustment was performed Emerging Energy Efficiency Technologies

  47. Lessons Learned and Recommendations Emerging Energy Efficiency Technologies

  48. M&V Lessons Learned • Challenging to collect detailed information in a large-scale project • Building and RTU characteristics • Servicing data • Possible error sources: • Recording by the field staff and service technicians • FDSI and PTHVAC estimates based off incorrect tonnages • Office staff entering data from faxed forms • Interpreting data and choosing PTHVAC package type for energy savings estimates • PTHVAC savings estimates • Disconnect between service technicians and owner/operators • Monitoring equipment issues • Most issues resolved after initial learning curve • HOBO/Onset issues: • HOBOlink data gaps • Weak connections in remote areas caused cell phone plans to reach their data transfer limit • Monitoring the cooling call Emerging Energy Efficiency Technologies

  49. Recommendations and Conclusions • Fan energy is a key factor in savings • Pre-screening: all units average 172 kWh/ton and 1,615 kWh • Limit unit age ≥ 5 years: • 228 kWh/ton • 2,225 kWh • Limit capacity ≥ 7 tons: • 301 kWh/ton • 3,268 kWh • Limit unit age ≥ 5 years and capacity ≥ 7 tons • 456 kWh/ton • 5,308 kWh • Heat pump winter operation requires additional research • Outside air temperature • Total unit power Emerging Energy Efficiency Technologies

  50. Recommendations and Conclusions • Measures • Thermostat measures generate the greatest savings, although persistence may be an issue • Minimum ventilation measurement needs more research • Minimum points for basic monitoring: outside air and power • Missed opportunity • Fan duty cycles could have been decreased on 24-7 units without 24-7 occupancy • Annual metering • Use these units to examine persistence, heat pump performance • Verification of annualization protocol and correlation between TMY3 and measured outside air temperatures Emerging Energy Efficiency Technologies

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