Residential Variable Capacity Heat Pump Field and Lab Testing: Final Results 20 November 2013 Ecotope 1

History Inverter-driven compressor tech making increasing inroads (ductless systems now at 20,000 plus installs in NW); BPA has incented central ducted systems via PTCS on provisional basis Advisory committee formed to guide research plan – Range of experience on committee – Interest in zoned systems, delivery temperatures – Timeline/budget limited research scope Study summary – Heating season only – ‘Detailed’ (full capacity/COP) vs non-detailed sites – Combination of field/lab info (EPRI) – ASHRAE 152 duct model exercised plus SEEM for full season estimates 2

Major Findings – Expectations/Reality VCHP performs 25-30% better than a single speed 7.9 HSPF heat pump on an annual basis (note nominal average HSPF for this product ~12). Duct losses increased ~5% over a single speed heat pump Overall system offers improved performance over single speed base cases Heat pump sizing still matters Auxiliary heat lockout control still matters 3

Field Deployment Planning/refinement occurred through late 2012 Field deployment set for late February, 2013 (six sites); central OR chosen for likelihood of remaining cold weather (about 24 potential sites) Critical points measured – 5 minute metering for electricity usage (including air handler circuit power- CFM mapping) – One-time measurements of house heat loss (including blower door test (system sizing, heating season simulation)), duct area/R-values, duct leakage, system CFM (at least 3 points so CFM could be correlated with power), heat pump control settings 4

Site Pictures 5

Site Summaries SiteidLocationOD unit size (tons) House Type Heated Floor Area (ft 2 ) OccsPTCS HP? PTCS Ducts ? Strip heat lockout temp Powell Butte, OR 3Site26942Yes not set Powell Butte, OR 2Mfd13942No Bend, OR 3Site26632YesNonot set Bend, OR 3Site25152Yes not set Redmond, OR 4Site18602No Redmond, OR 4Site26602No 35 6

Duct Leakage/Air Handler Data Site ID Both sides duct leak to out at 50 Pa* (SCFM) Supply duct leak to out at 50 Pa* (SCFM) Reference ‡ Air Handler Flow (CFM, SCFM)* Reference ‡ supply static pressure (Pa) Reference ‡ return static pressure (Pa) ***151***943, , n/a 889, , , , * Leakage and air handler flow results corrected to standard air (68°F and 1 atmosphere). The elevation of houses in the Bend area (about 3,000 ft above sea level) results in lower air density. More specifically, the density is about 88.9% of the density of standard air. The air handler flow values show both the local CFM and the standard SCFM. ‡ “Reference” airflow corresponds to the supply and return static pressure measurements shown in the table. Typically this airflow represents the highest flow that could be attained using the User Interface (thermostat); this measurement was taken to make sure the air handler was not working against an extreme external static pressure (above 200 Pa) at its highest flow. No adverse static pressure conditions were found. All of these systems were set up by the installer in COMFORT mode (so maximum flows typically average CFM/nominal ton of capacity). ***These measurements taken at 45 Pa 7

Airflow & Fan Power Site

Air Handler Curves - All Sites 9

Balance Points (for 2 sites) 10

Heat Pump Balance Points Site ID Peak total UA † (BTU/hr °F) DHL base ‡ (BTU/hr) DHL w/DE †† (Btu/hr) HP Balance Point (°F) Heat Pump Size (tons) ,63897, ,26026, , ,99669, ,45272, * All Design Heating Load (DHL) calculations based on 4° F design temperature. †Shell plus infiltration heat loss at heating design temperature ‡Design Heating Load without duct losses at the design temperature ††Design Heating Load with duct losses included 11

Detailed Field Results (834 monitored hours) 12

Capacity and COP Calculations Capacity determined by multiplying fitted airflow by coil temperature split True RMS power is measured at the panel for both indoor and outdoor units and converted to Btu/hr COP is ratio of capacity to input power at a given outdoor temperature Following 2 graphics do not include duct losses 13

Performance vs Outdoor Temp (1) (no duct effects included) 14

Performance vs Outdoor Temp (2) (no duct effects included) 15

Measured Field Performance (common five week period) Site ID Average Outdoor Temp. (F) Total Input (kWh) Total Output (kWh) COP (avg) ER heat output fraction Metered Time Span (hrs)

Compressor Response to Changing Heating Load Low compressor speed: input power < 1.25 x observed minimum input Medium compressor speed: anything in between low and high High compressor speed: input power > 0.87 x observed maximum input 17

Air Handler Response to Changing Heating Load Low fan speed: airflow < 1.25 x listed minimum airflow (comfort mode) Medium fan speed: anything in between low and high High fan speed: airflow > 0.87 x listed maximum airflow (comfort mode) 18

Operating Mode Summary Fan and compressor speeds track one another – Given a compressor speed, there is a preferred fan speed – High compressor outputs almost never pair with low and medium fan – Low compressor speeds pair with both low and medium fan Runtime Fractions: Compressor Only Operation Compressor Speed Fan Speed LowMediumHighAll Low Medium High All Compressor and Auxiliary Operation Compressor Speed Fan Speed LowMediumHighAll Low Medium High All

Rolling in the Ducts… 20

Duct System Inputs Duct leakage, normalized to fraction of air handler flow (which changes at different flows) Duct R-value Duct area Buffer space temperature (measured only for supply buffer space) ASHRAE 152 used to calculate distribution efficiency 21

Average Duct Performance and Calculated Duct Distribution Efficiency (DE) (common five week period) Site ID System Airflow (CFM) Avg Supply Buffer Zone Temp (°F)SLFRLFDE n/a

Modeling VHCPs – Annual Performance Annual performance estimated with SEEM Simulation largely unchanged from September 2012 RTF presentation – Performance curve from catalogue data found to work well enough for systems modeled – Field study found that the operating modes pair fan and compressor speed (previous default assumption in simulation – remains unchanged) 23

Modeled VCHP and Duct System Efficiency (using SEEM for entire heating season) 24

Lab (EPRI) vs Field Results Agreement on capacity and COP measurements generally good; more divergence for some cases Lab tests done in EFFICIENCY mode All sites in Oregon set up in COMFORT mode Lab showed higher COPs as expected because of EFFICIENCY vs COMFORT mode Possibility of variability for individual pieces of equipment, as well 25

Lab results Field results Lab vs Field Comparison (2 ton system) 26

Overall Findings 27 VCHP performs 25-30% better than a single speed 7.9 HSPF heat pump on an annual basis Duct losses increased ~5% over a single speed heat pump Overall system offers improved performance over single speed base cases Heat pump sizing still matters Auxiliary heat lockout control still matters

Next Possible Steps Cost analysis. Collect data on installed costs and compare to annual estimates of savings. More complete set of SEEM runs- additional comparisons to base cases (HP and/or EFAF) Possible UES process (depends on cost analysis) Further discussion of how system could be commissioned (PTCS) 28