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Air Source Heat Pumps. Potential Changes in the RTF’s Specifications & Savings Estimates and Their Impact on C&R Discount Program Credits. Why “Things” Are Changing – New Energy Star Specifications.

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air source heat pumps

Air Source Heat Pumps

Potential Changes in the RTF’s Specifications & Savings Estimates and Their Impact on C&R Discount Program Credits

why things are changing new energy star specifications
Why “Things” Are Changing – New Energy Star Specifications
  • Energy Star labeled air source heat pumps established new performance criteria effective October 1, 2002
    • Split System Minimums
      • SEER – 13.0
      • HSPF - 8.0
      • EER – 11.0
    • Package System Minimums
      • SEER – 12.0
      • HSPF – 7.6
      • EER – 10.5
why things are changing pnw climates are different
Why “Things” Are Changing – PNW Climates Are Different
  • 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
why things are changing control practices reduce performance
Why Things Are Changing – Control Practices Reduce Performance
  • Set-Back Thermostats (with or without “ramp up” features) often result in use of electric resistance heat
  • Timed-defrost controls (particularly in Heating Zones 2 & 3) operate even when relative humidity is too low to produce icing
  • Compressor “cut-out” temperatures are set too high, so compressor doesn’t operate even when it has a COP above 1.0.
why things are changing failure to properly commission heat pumps
Why Things Are Changing - Failure to Properly Commission Heat Pumps
  • Field studies of heat pump and air conditioner installations reveal
    • Over/Under Charging of Refrigerant
    • Low air flow across evaporator coils
seer doesn t match label either
SEER Doesn’t Match Label Either
  • High performance air conditioning equipment is designed to “de-humidify” by recovering latent energy (heat of condensation)
  • Preliminary research appears to show that SEER ratings, when adjusted for the PNW “dry-summer” climate are about 65% of nameplate
    • Nominal 10 SEER => Real 6.5 SEER
other factors that are changing rtf s heat pump savings
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
slide17
However, Some Revised Estimates of Air Conditioning Load Are Higher and Lower (e.g.,Post79/Pre93 Construction)
overall implications for c r discount values
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