HPWH UES Measure Initial Review16 April 2014

Agenda

• Provisional Measure Review• Method Overview• Prelim Findings• Measure Development Approach• Simulation Validation

Please provide feedback and concerns throughout. This is a brainstorming session as much as a presentation.

Current Provisional Measures• HPWH Type:

– Tier 1, 50-75 gallons– Tier 1, 75+ gallons– Tier 2

• Unheated buffer locations – Includes garages and basements together

• Heated installations – One measure for each of gas furnace, electric furnace, zonal resistance, and heat pump heating

• Tier 1 water heaters have no exhaust ducting• Tier 2 water heaters all have exhaust ducting

• The measures cross the entire PNW and are not separated by climate zone

Annual Energy Saving (kWh/yr) Tier 1 Tier 2

HPWH Location Space Heat TypeSmall Tank

Large Tank Any Size

Unheated Buffer Location Any Heat Type 887 1,817 1,794 Interior Location Gas Heated Home 1,547 2,169 1,724 Interior Location Zonal Electric Heated Home 648 957 952 Interior Location Electric Furnace Heated Home 556 833 837 Interior Location Heat Pump Heated Home 1,189 1,686 1,243

Method

Proven Unit Energy Savings

• Calibrated Engineering Approach– Heat Pump Water Heater Model Validation and

Process Evaluation Project designed specifically to move HPWH measure from provisional to proven status. • Even designed under the current guidelines (hooray!)

– Final energy savings will be calculated with a simulation of HPWH behavior• Inputs to simulation need to be solid• Simulation needs to be validated

Simulation Inputs & Characteristics

• Simulation inputs come from the completed field studies:– Inlet water temperature, ambient air temperature,

tank set point, water draw pattern– Investigated, categorized, and normalized where

necessary (e.g. by climate or number of occupants)• To extend to entire PNW, additional

characteristics will come from RBSA survey– Ex: occupant count

Simulation Validation

• Validated against field measurements of energy use– Categorized by climate, equipment type,

installation location, draw patterns, etc.

Preliminary Findings(subject to change. your mileage may vary. etc.)

• Findings used in two, broad ways:– For simulation inputs– To validate outputs

Findings are as expected:• Energy use

GeoSpring>Voltex>ATI• Resistance heat slope is

about 0.2 kWh/gal

Findings are as expected: • Energy use

Garage>Basement>Interior

More Findings

• Inlet water – by region / climate

• Ambient air temperature – by install location

• Outlet water – input from site visit records on setpoints– measured outlet temperatures

• Will use inlet measurements to build inlet water temperature profiles for use in simulation as a function of geography

Creating Hot Water Draw Profiles

• Average daily use per person: 17.1 gallons– Provisional measure used 18.2 gallons

• Will also investigate the following to inform our draw patterns:– Average number of draws per person per day

• at 1 gallon resolution– Draw sizes

• Ex: # of 1 gal draws, # of 2 gal draws, # of 3 gal draws, etc….

Final UES Development Approach

• Categories and Prototypes– Are calculated and modeled separately but then

combined with weighted averages to produce ultimate savings estimates• Climate Zone• Installation Location• Heating System Type• Prototypical Draw Patterns

– 1, 2, & 4 person draws

Key Assumptions• RBSA population characteristics represent the houses installing

HPWHs• Water draws are the same between ERWH and HPWH

– Both are storage tanks– Metered energy data from DHP study and RBSA Metering study can

help confirm• Space heating interaction

– Fractional or full?• Current assumption for interior installations is full interaction: one unit of heat

removed from the air in the heating season is replaced by one unit of heat output from the heating system

– Supplemental heat• A negative heating interaction will show up as a change in supplemental heat

requirements. Those heat requirements, per the DHP analysis, will show up as a cost in the non-energy benefits stream and not as a penalty to the electric grid.

Schedule

• All analysis currently underway• Report writing in April & May• Workbook development in May & June• Workbook refinement in June & July• Final report before RTF presentation• Full RTF presentation in July or August

Simulation Validation

• Graphs of metered and simulated data• Work still underway to tune the simulation

Voltex 60: Measured & Modeled

Voltex 80: Measured & Modeled