Proposed Changes to the RTFs Heat Pump Specifications

1
Proposed Changes to the RTFs Heat Pump
Specifications
Impact on Estimated Deemed Savings and CR
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 Northwests.
• 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 gt 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
  manufacturers 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 _at_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 RTFs 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 CR 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
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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
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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 Richlands
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