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Proposed Changes to the RTF’s Heat Pump Specifications

Proposed Changes to the RTF’s Heat Pump Specifications. Impact on Estimated Deemed Savings and C&R Discount Program Credits. PNW Climates Are Different Than That Used for ARI Ratings. ARI performance ratings (SEER & HSPF) are based on climates that do not match the Northwest’s.

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Proposed Changes to the RTF’s Heat Pump Specifications

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  1. Proposed Changes to the RTF’s Heat Pump Specifications Impact on Estimated Deemed Savings and C&R Discount Program Credits

  2. PNW Climates Are Different Than That Used for ARI Ratings • ARI performance ratings (SEER & HSPF) are based on climates that do not match the Northwest’s. • Heating Zone 1 climate is warmer than the rating location – HSPF is higher than label • Heating Zones 2 & 3 climates are colder than the rating location – HSPF is lower than label • All of the Cooling Zones in NW has lower humidity than the rating location – SEER is lower than label

  3. Climate Adjusted HSPF

  4. Duct Leakage and Insulation Levels Have Interactive Affects on System Efficiency • Duct leakage and conductive losses reduce heat pump capacity. • Duct leakage and conductive losses increase “buffer space” temperatures. • As a result, duct location, duct leakage and insulation levels must all be modeled to determine overall “duct system” efficiency.

  5. Duct “System” Assumptions • Four Duct Configurations • Crawlspace – Supply ducts 100% outside conditioned space • ½ Basement - Supply ducts 50% outside conditioned space • Full Basement - Supply ducts 100% inside conditioned space • Manufactured Home - Supply ducts 100% outside conditioned space • Three Levels of Leakage • 10% - Base • 7.5% - RTF • 5% - PTCS • Two Levels of Duct Insulation • R-4 – Base • R-11 (R-8 installed) – RTF & PTCS

  6. Duct System Efficiency Adjusted HSPF – All Ducts Outside Conditioned Space

  7. Duct System Efficiency Adjusted HSPF – > 50% Ducts Outside Conditioned Space

  8. Duct System Efficiency Adjusted HSPF – Manufactured Home Supplies Outside Conditioned Space

  9. Duct System Efficiency Adjusted HSPF – All Ducts Inside Conditioned Space

  10. Commissioning Heat Pumps – Adjustments for Improper Air Flow and Refrigerant Charge • Field studies of heat pump and air conditioner installations reveal • Over/Under Charging of Refrigerant • Low air flow across evaporator coils • RTF Specifications require: • Air flow verification using either flow plate or “temperature rise” & “volt/amp” methods • Refrigerant charge verification “according to manufacturer’s instructions” • PTCS Specifications require: • Air flow verification using flow plate (TrueFlow) • Refrigerant charge verification using SubCool/SuperHeat in AC mode.

  11. Commissioning Adjusted HSPF

  12. Control Impact Assumptions • Base Case Assumptions • Combination Timer Defrost (20%) & Demand Defrost (80%) • Some (20%) of systems have w/low ambient temperature compressor “cutouts” • Some (20%) systems have resistance backup tied to “first stage” of heat pump • RTF Assumptions • Demand Defrost Only • Some (20%) systems have outside thermostats which limit “backup” above 35F • No resistance backup tied to “first stage” of heat pump • PTCS Assumptions • Demand Defrost Only • All systems have outside thermostats which limit “backup” above 35F

  13. Control Adjusted HSPF

  14. Cumulative Adjusted HSPF – All Ducts Outside Conditioned Space

  15. Cumulative Adjusted HSPF – 50% Ducts Outside Conditioned Space

  16. Cumulative Adjusted HSPF – All Ducts Inside Conditioned Space

  17. Cumulative Adjusted HSPF – Manufactured Homes – All Supplies Outside Conditioned Space

  18. SEER Adjustment • High performance air conditioning equipment is designed to “de-humidify” by recovering latent energy (heat of condensation) • ARI Test Conditions assume inside temperature of 80F and outside temperature of 82F and relative humidity @100%, 90% and 80% • Preliminary research appears to show that SEER ratings, when adjusted for the PNW “dry-summer” climate are about 65% of nameplate

  19. Other Factors That Are Changing RTF’s Heat Pump Savings • Revised estimates of “post-weatherization” space heating use • Reduced loads • Revised estimate of air conditioning loads • New estimates based on hourly modeling of specific prototypes • Better calibration with metering studies for space heating and cooling

  20. Pre1980 Construction “Post Weatherization” Forced Air Furnace Space Heating Use

  21. Post79/Pre93 Construction Forced Air Furnace Space Heating Use

  22. Post92 Construction Forced Air Furnace Space Heating Use

  23. Revised Estimates of Air Conditioning Loads Are Lower (e.g.,Pre1980 Construction)

  24. Revised Estimates of Air Conditioning Load Are Lower (e.g., Post92 Construction)

  25. Some Revised Estimates of Air Conditioning Load Are Higher and Lower (e.g.,Post79/Pre93 Construction)

  26. Overall Implications for C&R Discount Values • Difference Between “PTCS” Heat Pump (or CAC) Installations & Non-“PTCS” Installations Increases • Difference between Non-PTCS Heat Pump (or CAC) Installations and “Baseline” Installations Decreases

  27. Air Source Heat Pump Savings for Pre1980 FAF w/o CAC with PTCS

  28. Air Source Heat Pump Savings for Post79/Pre93 FAF w/o CAC with PTCS

  29. Air Source Heat Pump Savings for Post1992 FAF w/o CAC with PTCS

  30. Air Source Heat Pump Savings for Pre1980 FAF w/o CAC – with RTF Specification

  31. Air Source Heat Pump Savings for Post79/Pre93 FAF w/o CAC – with RTF Specifications

  32. Air Source Heat Pump Savings for Post1992 FAF w/o CAC – with RTF Specifications

  33. Air Source Heat Pump Savings for Pre1980 FAF w/o CAC – with PTCS vs. RTF Specifications

  34. Air Source Heat Pump Savings for Post79/Pre93 FAF w/o CAC – with PTCS vs. RTF Specifications

  35. Air Source Heat Pump Savings for Post1992 FAF w/o CAC – with PTCS vs. RTF Specifications

  36. City of Richland Savings Estimates • Based on sub-metered data on 54 homes • Average house size = 2071 sq.ft. • Average savings = 5552 kWh/yr • (2.7 kWh/sq.ft./yr) • Average HSPF = 8.24 • Un-reported Pre-conversion space conditioning use and CAC system

  37. RTF Estimates Compared to City of Richland’s Analysis – Heating Only Savings

  38. Recommendations • Adopt revised deemed savings estimates for air source heat pump conversions (and heat pump and CAC efficiency upgrades) • Consider using kWh/sq.ft./yr as “deemed unit” rather than kWh/yr/home • Revise assumptions in Heat Pump HSPF and CAC SEER “Tradeoff Calculator” to match deemed savings analysis

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