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RTU Savings/ MWa – NPCC 6 th Power Plan

Review: Standard Protocol for Measurement of Fan and Cooling Savings from Commercial-Sector Packaged Rooftop HVAC Units Regional Technical Forum February 14, 2012. RTU Savings/ MWa – NPCC 6 th Power Plan. RTUs in 6 th Power Plan….

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RTU Savings/ MWa – NPCC 6 th Power Plan

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  1. Review:Standard Protocol for Measurement of Fan and Cooling Savings from Commercial-Sector Packaged Rooftop HVAC UnitsRegional Technical ForumFebruary 14, 2012

  2. RTU Savings/MWa– NPCC 6thPower Plan

  3. RTUs in 6th Power Plan…

  4. NW Commercial Building Stock Assessment(CBSA) RTU counts-6th Power Plan 52% floor area <50kSf Population 64% of buildings <6 tons 79% of buildings <10 tons

  5. PNW RTUs an aging fleet… 51% = 204,000 of the units have been on the roof for over a decade!

  6. RTU Protocol Issues Raised • Measure exclusions: which measure are excluded even though not tested? • Pre and Post upgrade scheduling: can we do Pre in August and Post in May? • Multiple annual site review to better understand confidence interval • Cost to implement the protocol needs closer review: cost estimate based on mature program and lessons learned • Calculator is for a single unit; sampling protocol is for program evaluation purposes, not unit savings calculations • All protocols and calculators will need ongoing RTF support (2013 work plan/budget)

  7. RTU Protocol Confidence LimitsLimited Sites • Confidence limits are normalized relative to annual energy • Confidence limits highest for metering periods starting in late June to mid-July • Confidence limits of +- 5% are achieved with metering periods starting in late May and early August

  8. Assessment of 90% Confidence Intervals (West)

  9. Assessment of 90% Confidence Intervals (East)

  10. Nominal 90% Confidence Intervals (East)(Actual coverage rate around 50%)

  11. Nominal 90% Confidence Intervals (West)(Actual coverage rate around 50%)

  12. RTU M&V Field Protocol • Purpose • Definition of Key Terms • Required Knowledge and Skills of Practitioner • Required Data Logger Commissioning • One Time Site Measurements and Descriptions • Data Logger Measurements • TMY3 Weather Data • Savings Estimation Steps • Estimate of Typical Measurement Cost • Relationship to Other Protocols and Guidelines • Sampling Procedure for Program Evaluation

  13. Purpose • Establishes a method by which annual electrical cooling and fan energy use and savings (kWh) can be estimated for a commercial packaged rooftop unit (RTU) optimized for performance including in-field data collection requirements/methods, annualized use/savings calculation method

  14. Definition of Key Terms • Baseline • Pre • Post • Commissioning: • data logger/storage/comm equipment • RTU post-upgrade • Upgrade Measures

  15. Required Knowledge and Skills of Practitioner • Appropriate electrical and related safety procedures • Knowing the protocol and calculator • Equipment inspection: control points, schedules, cooling stages • Logging equipment selection and use • Measurement equipment commissioning • Ability to interpret results

  16. Required Data Logger Commissioning • Communications & data storage • True power sampling with current transducers @ 3-minute interval • If site temperature measurement is used, verify temperatures with 2nd instrument • If supply air temperature is used, place away from supply air plenum walls • Full data set should be tested immediately • Onboard data storage up to 70 days @ 3-min interval

  17. Key Measurement Considerations • Outdoor air temperature on site or nearby NOAA weather station • Supply air temperature optional: for diagnostics, not calculator • Timing of measurement: 4 wks pre/4 wks post pre: 3rdwk May-June; post: 1stwk August-Sept • Timing of retrofit: July

  18. Savings Estimation • Automated calculator with true power/temperature data only Sequence of Calculations: • Compute the Normalized Annual Consumption (NAC) for pre/post data • Energy Savings Calculation Sequence • Electric Load Shape Calculation Sequence • Demand Savings Calculation Sequence

  19. Estimate of Costs • Mature case with lessons learned • Expedited approach using NOAA weather for 2 RTUs in same panel = $1250 or $635/RTU • Comprehensive approach site weather, 3 RTUs single roof = $2,450 or $817/RTU

  20. Annualized Energy Use / SavingsCalculator

  21. Next Steps • February 16, 9am-12pm RTUG follow up meeting to Feb 14 RTF review • RTF members invited to participate • Planning to make final protocol recommendation at March RTF meeting

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