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.

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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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

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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

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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

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This project was supported by a grant from the
Minnesota Department of Commerce through the
Conservation Applied Research and Development
(CARD) program.

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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

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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

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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

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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

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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

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How HPWHs work

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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. Cold Climate Considerations

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Coefficient of Performance
From: Steven Winter 2011 Measure Guideline for HPWHs

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Capacity and Inlet Water
• Cold inlet water temps
• Directly impact capacity
• HP > ER in capacity
• Cold inlet water may
cause increased ER use

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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

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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. Installation Considerations

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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. Performance

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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…

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COP for electric water heaters

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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

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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

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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

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Peak load energy consumption

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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

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Peak Loads: Resistance, HPWHs, and
Thermal Storage

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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/

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Homeowner Application Outputs

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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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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

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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

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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

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Whole House Integration
• Waste Heat
• Bathroom Exhaust
• Mechanical Room
• Refrigerator
• Integration with other systems
• Mechanical Ventilation

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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. Ben Schoenbauer | 612.244.2413
bschoenbauer@mncee.org

41. Question & Answer
Webinar Link:
http://www.mncee.org/Innovation-Exchange/Resource-Center/

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