Quantifying Energy Savings from Heat Pump Water Heaters in Cold Climate Homes

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Senior Research Engineer Ben Schoenbauer covers findings from his recent study and app development, explaining how heat pump water heaters affect homes from a whole house perspective.

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Quantifying Energy Savings from Heat Pump Water Heaters in Cold Climate Homes

  1. 1. HEAT PUMP WATER HEATERS IN COLD CLIMATE HOMES Quantifying Energy Savings Ben Schoenbauer | Center for Energy & Environment Webinar: May 13, 2014
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  4. 4. Pg. 4 GHG Performance Standards & Energy Efficiency: MN & the Midwest Look Ahead Webinar: Thursday, May 22nd 1:00 - 2:15 pm CST Jessica Burdette Conservation Improvement Program Supervisor MN Department of Commerce Division of Energy Resources Target Audiences • Midwestern clean air and energy regulators • Midwestern public utility Commissioners • Utility professionals • Energy analysts • Environmental and energy advocates Frank Kohlasch Air Assessment Section Manager MN Pollution Control Agency Environmental Analysis & Outcomes Division Jon Brekke Vice President of Membership & Energy Markets Great River Energy
  5. 5. Pg. 5 How Utilities are Benefiting From Minnesota’s New Energy Savings Platform Webinar: Tuesday, June 24th 11:00 - 12:00 pm CST Joe Plummer Public Utilities Rates Analyst, ESP Program Mgr. MN Department of Commerce Division of Energy Resources Target Audiences • Minnesota utility program managers • Minnesota utility operations managers • Minnesota policymakers • Energy regulators in other states • Energy platform developers Jeff Haase Energy and Efficiency Conservation Program Mgr. Great River Energy
  6. 6. Pg. 6 Today’s Presenter • At CEE since 2008 • Specializes in water heating and combination heating technologies • Collaborator on Building America research • Master’s degree in Mechanical Engineering Ben Schoenbauer Senior Research Engineer
  7. 7. Pg. 7 This project was supported by a grant from the Minnesota Department of Commerce through the Conservation Applied Research and Development (CARD) program.
  8. 8. Pg. 8 GBCI Learning Objectives 1. Best installation practices for high performance electric water heaters 2. Heat transfer impacts of heat pump appliances 3. Household characteristics can be used to estimate domestic water heater loads 4. The electric peak load impacts of different water heating technologies and what consequences these technologies have for utilities and homeowners
  9. 9. Pg. 9 Agenda • Electric Water Heating Overview • Introduction to HPWHs • Cold Climate Impacts • Installation • Savings and Simple Paybacks • Peak Load Impacts • CEE Applications • Homeowner • Utility/Program Management • What’s Next
  10. 10. Pg. 10 Electric Water Heating • 30% of Midwestern Homes used electric water heating • In Minnesota, typically homes outside the TC metro area • Many electric co-op and municipalities are interested in water heating as a peak load reduction possibility • Some new construction looking at electric WH to avoid combustion safety issues
  11. 11. Pg. 11 Standard Tech: Electric Storage • Water stored at temperature • When tank temp drops below certain point elements turn on • Rated EF from 0.89 to 0.95 • Insulation levels main difference • Typical input: 4 to 6 kW • Typically 40 to 60 gallons of storage • No burner venting results in lower storage loses than similar gas units • Hot water delivery similar to gas storage WHs
  12. 12. Pg. 12 Heat Pump Water Heaters • Integrated heat pump and storage • 50 to 80 gallons • COP ~ 2 to 2.5 • Optional ducted venting • Cooling capacity of 15 to 30 kBtu/hr (~1.2 to 2 tons) • Multiple modes of operation • Heat pump only • Hybrid • Resistance only
  13. 13. Pg. 13 How HPWHs work
  14. 14. Pg. 14 Common Concerns • Cold Climate Considerations: • The impact of HPWHs on the space conditioning load. • The impact of cooler ambient temperatures on HPWH efficiency and capacity. • Installation/Durability/Operation • Reliability and maintenance. • Space needs and the impacts of the installation location on performance. • Reliance on occupant to keep the unit in HPWH mode and not change to resistance only. • Noise.
  15. 15. Cold Climate Considerations
  16. 16. Pg. 16 Coefficient of Performance From: Steven Winter 2011 Measure Guideline for HPWHs
  17. 17. Pg. 17 Capacity and Inlet Water • Cold inlet water temps • Directly impact capacity • HP > ER in capacity • Cold inlet water may cause increased ER use
  18. 18. Pg. 18 Cold Climate: Space Conditioning • Lots of modeling around the country, field data is difficult • Lots of variables: • Installation location • In conditioned space – Max effect • In garage – No effect • In semi-conditioned (basement/craw space) – secondary effect • Conditioning load of house and heating equipment • Efficiency, set points, use, etc • Limited lab data shows HPWHs deliver ~1 ton of cooling at 50 gallons per day
  19. 19. Pg. 19 Cold Climate: Space Conditioning • location is important • Smaller Impact with • Unfinished basement • Efficiency HVAC system • Cheap fuel • Low DHW Use • High Impact • Conditioned Space • Inefficient HVAC • Expensive fuel • High DHW Use
  20. 20. Installation Considerations
  21. 21. Pg. 21 Installation considerations • Must have adequate room air to draw heat from • Most manufacturers around 800 cu ft (10’ x 10’ with 8’ ceiling) • Smaller rooms • Louvered doors • Ducting • Height • Units typically about 12” taller than standard • HP units at top, need room for maintenance • Reduction of surrounding air temperature and humidity • Noise • New units are greatly improved, 35 decibels or less • Older units were 50 + decibels • Refrigerators are 40 to 50 decibels, for comparision
  22. 22. Performance
  23. 23. Pg. 23 Savings • HPWHs on average save $250 per year (from ratings) • Simple paybacks in typical homes of about 3-6 years • Actual savings depend on lots of parameters • Tool will include impacts of • Installation location • Impact on space heating load • Ambient temperatures • And more…
  24. 24. Pg. 24 COP for electric water heaters
  25. 25. Pg. 25 Savings 2 or 3 people - Spread out showers Metro Area Full Make- Up Partial Make-up No Make- Up Electric - Resistance -$54 $104 $210 Electric - ASHP (COP 1.9) $82 $159 $210 Natural Gas - Standard Efficiency $127 $177 $210 Natural Gas - High Efficiency $141 $182 $210 Propane - Standard Efficiency $18 $133 $210 Propane - High Efficiency $45 $144 $210 Fuel Oil - Standard Efficiency -$11 $122 $210 Fuel Oil - High Efficiency $14 $131 $210 Total Savings $/yr
  26. 26. Pg. 26 Costs • More variability than standard units • Newer technologies often have changing equipment costs • Larger height may case plumbing modifications • Ducting will add cost if necessary • Modifications to surrounding space will add cost, if necessary (louvered doors) • NREL Energy Efficiency Database • HPWH installed $1400 to $2600 • Electric Resistance tank $400 to $800 • Average incremental cost of $1150 about $750 of this is WH incremental cost
  27. 27. Pg. 27 Savings 2 or 3 people - Spread out showers Metro Area Full Make- Up Partial Make-up No Make- Up Electric - Resistance -$54 $104 $210 Electric - ASHP (COP 1.9) $82 $159 $210 Natural Gas - Standard Efficiency $127 $177 $210 Natural Gas - High Efficiency $141 $182 $210 Propane - Standard Efficiency $18 $133 $210 Propane - High Efficiency $45 $144 $210 Fuel Oil - Standard Efficiency -$11 $122 $210 Fuel Oil - High Efficiency $14 $131 $210 Total Savings $/yr Full Make-Up Partial Make-up No Make- Up #N/A 10.6 5.2 13.4 6.9 5.2 8.7 6.2 5.2 7.8 6.0 5.2 61.1 8.3 5.2 24.4 7.6 5.2 #N/A 9.0 5.2 78.6 8.4 5.2 Simple Paybacks years
  28. 28. Pg. 28 Peak load energy consumption
  29. 29. Pg. 29 Electric Thermal Storage • Increases the temperature WH at low electricity use periods (overnight) • Not an energy savings measure, but reduces peak load • Units typically have larger storage capacity's, 60 gallons plus • Some units have increased insulation to prevent increasing stand by loses
  30. 30. Pg. 30 Peak Loads: Resistance, HPWHs, and Thermal Storage
  31. 31. Pg. 31 Homeowner application • Homeowner inputs information about their home • Hot water use • House location • Water heater installation location • Heating and cooling system information • Application Outputs • Estimated energy savings • Estimated space conditioning impact • Electric usage profile • http://mncee.org/Innovation-Exchange/Resource- Center/Data-and-Reference/Heat-Pump-Water- Heater-Calculator/
  32. 32. Pg. 32 Homeowner Application Outputs
  33. 33. Pg. 33 Utility Application • For use by utilities or program managers • Similar inputs as homeowner app, but based on percentages • Application outputs • Savings per home • Conditioning impact • Impact on peak by percentage of customers that use HPWHs • Finalizing development
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  35. 35. Pg. 35 What to look for moving forward • Thermal storage with heat pumps • Use of venting • Ventilation impacts • Whole house integration • Ratings changes/cold climate consideration • Gas Fired HPWHs
  36. 36. Pg. 36 Thermal Storage with HPWH • TVA, PNNL, EPRI and water heater manufacturers conducting research • Off peak heating • Short term grid interaction • Off peak heating has greater potential • PNNL - ACEEE Hot Water Forum Presentation • EPRI – ACEEE Hot Water Forum Presentation
  37. 37. Pg. 37 Ducting and Mechanical Ventilation • HPWH exhaust can be ducted outside of the building • Exhaust fans typically operate between 150 and 300 CFM • ASHRAE 62.2 typically requires ventilation rates between 40 and 70 CFM • HPWH ventilation is intermittent and may not offset the need to mechanical ventilation, but integration of these two systems can provide an energy benefit
  38. 38. Pg. 38 Whole House Integration • Waste Heat • Bathroom Exhaust • Mechanical Room • Refrigerator • Integration with other systems • Mechanical Ventilation
  39. 39. Pg. 39 Ratings • New water heating ratings coming • Proposed rulemaking published by DOE in November 2013 • Congress requires them to finalize rule ASAP • New water usage profiles • Possible changes in delivery and set point temperature • NEEA has developed Cold Climate Specification • Involves testing HPWHs at colder ambient conditions • Required higher performance (COP, noise reduction, flexibility)
  40. 40. Ben Schoenbauer | 612.244.2413 bschoenbauer@mncee.org
  41. 41. Question & Answer Webinar Link: http://www.mncee.org/Innovation-Exchange/Resource-Center/
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