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Mark Cherniack Howard Reichmuth New Buildings Institute

RTU Savings Research Project: Findings and Recommendations Regional Technical Forum February 3, 2009. Mark Cherniack Howard Reichmuth New Buildings Institute. RTU Savings Research Project . Phased RTU Research program

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Mark Cherniack Howard Reichmuth New Buildings Institute

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  1. RTU Savings Research Project: Findings and RecommendationsRegional Technical ForumFebruary 3, 2009 Mark Cherniack Howard Reichmuth New Buildings Institute RTU Savings Research Project

  2. RTU Savings Research Project • Phased RTU Research program • Phase 1: Identify the known savings and cost-effectiveness data; establish priorities for Phase 2 research • Phase 2: Conduct the Phase 1 recommended research activities • Phase 3: To be determined by outcome of Phase 2; an expanded field test was envisioned RTU Savings Research Project

  3. Phase 2 RTU Research Project • Bench test controller/sensor issue • Apply field measurement and service protocol to RTUs • Develop an annual savings methodology based on the measured data • Review existing utility RTU program data • Propose a Phase 3 work plan RTU Savings Research Project

  4. Review Existing Data Set • 70% had the controller being tested • 1% used enthalpy sensors with unknown drift and calibration, although only dry-bulb sensing is necessary in our climate • 56% had only a single stage of cooling wired, which significantly curtailed economizer use • 73% used single changeover point (one outdoor sensor and no return air sensor), 27% used a differential changeover strategy RTU Savings Research Project

  5. Phase 2 RTU Research ProjectBench Test • Economizer control problem identified • Tested specific Honeywell controller/sensor combo • Found 6-10 degF deadband in sensor-limited economizer cooling • Honeywell verifies sensor finding • Recommendations made for new sensor RTU Savings Research Project

  6. RTU Savings Research ProjectBench Test RTU Savings Research Project

  7. RTU Savings Research ProjectBench Test- Honeywell Sensor Specs C7650 C7660 RTU Savings Research Project

  8. RTU Savings Research ProjectBench Test Recommendations • Ensure that the old Honeywell sensor is not being used in new HVAC units coming in through utility HVAC EE programs • Notify a wide band of HVAC market stakeholders • Establish benefits of adding the new sensor to utility RTU field service protocols • Consider regional bulk sensor purchase RTU Savings Research Project

  9. RTU Savings Research Project RTU Field Measurement & Service Protocol • 9 initial sites recruited; 5 have little cooling load. 3 sites provided sufficient signature data for analysis and consideration • Metering was more than sufficient for the minimum monitoring package • Analyzed three preliminary Bonneville sites RTU Savings Research Project

  10. RTU Savings Research ProjectRTU Service Protocol • Thermostat reset and/or replacement • Measured airflow through the evaporator • Economizer system check • Additional control potential • Refrigerant charge check/adjustment as needed RTU Savings Research Project

  11. RTU Savings Research ProjectRTU Monitoring • RTU total power • RTU fan power • Gas burner status • Damper position • Condensate flow • Outdoor air temperature (2 measurements) • Return/mixed (4 measurements) temperatures • Supply air temperature RTU Savings Research Project

  12. RTU Savings Research ProjectRTU Monitoring Results RTU Electric Signature RTU Savings Research Project

  13. RTU Savings Research Project Anatomy of an RTU Energy Signature • Cooling balance point temperature • ‘Flat’ low temperature slope • Cooling slope RTU Savings Research Project

  14. RTU Savings Research ProjectRTU Monitoring Results RTU Gas Signature RTU Savings Research Project

  15. RTU Savings Research ProjectRTU Monitoring Results % Outside Air Map RTU Savings Research Project

  16. RTU Savings Research ProjectRTU Monitoring Results Economizer Control Temperature Map RTU Savings Research Project

  17. RTU Savings Research ProjectBonneville Unit Hourly Max Power vs Temperature RTU Savings Research Project

  18. RTU Savings Research ProjectRTU Monitoring Results Economizer Effect RTU Savings Research Project

  19. RTU Savings Research ProjectAnnual Savings Methodology • Average daily site temperature • Daily RTU energy [electric/gas] signature • Histogram of site daily normal avg temperature @ 5 degF bins (consistent with Bonneville data) • Signature x histogram = daily RTU energy • Normalized annualized RTU energy is annual sum of daily RTU energy RTU Savings Research Project

  20. RTU Savings Research ProjectAnnual Savings Methodology #1 Finding: With a few weeks pre- and post-data on a regularly operating building, an estimate of annual energy use and therefore savings, can be reliably made. Data needs to be studied in detail to gain confidence in interpreting the results. RTU Savings Research Project

  21. RTU Savings Research ProjectKeys To Annual Savings Methodology • 4 diagnostic graphs are needed for a high confidence energy savings estimate • Mode by power map = accurate kW savings • % outside air map • Economizer temperature control map • RTU energy performance map RTU Savings Research Project

  22. Preliminary Bonneville Site RTU DataSite 895 Initial RTU Performance Map RTU Savings Research Project

  23. Preliminary Bonneville Site RTU DataSite 895 Daily RTU Energy Profile RTU Savings Research Project

  24. Preliminary Bonneville Site RTU DataSite 895 RTU Performance Map RTU Savings Research Project

  25. Preliminary Bonneville Site RTU DataSite 895 - 8900 kWh savings RTU Annual Energy by Temperature Bins RTU Savings Research Project

  26. Preliminary Bonneville Site RTU DataSite 897 RTU Performance Map RTU Savings Research Project

  27. Preliminary Bonneville Site RTU DataSite 897 - 9300 kWh savings RTU Annual Energy by Temperature Bins RTU Savings Research Project

  28. Preliminary Bonneville Site RTU DataSite 899 RTU Performance Map RTU Savings Research Project

  29. Preliminary Bonneville Site RTU DataSite 899 - 1030 kWh savings RTU Annual Energy by Temperature Bins RTU Savings Research Project

  30. RTU Savings Research Project Recommendations - Phase 3 • Apply measurement/monitoring protocol-- >> To all remaining Bonneville existing sites >> In all new field monitoring projects including the Premium Ventilation Package and Bonneville’s upcoming field monitoring project [60+ sites?] • Current models should be reconciled to existing/new unit level data • Subset monitored annually at least 5 years • Fan power savings are very important: 24-hr operation • More aggressive economizer control: pre-cooling RTU Savings Research Project

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