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

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.

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

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

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)

Ben Schoenbauer | 612.244.2413

bschoenbauer@mncee.org

Question & Answer

Webinar Link:

http://www.mncee.org/Innovation-Exchange/Resource-Center/

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