Heat Pump Water Heater ACE Model Review

The Northwest Energy Efficiency Alliance (NEEA) contracted with Ecotope, Inc. to review recent updates to the methodology of the Alliance Cost Effectiveness (ACE) model for its Heat Pump Water Heater (HPWH) program, specifically regarding updated assumptions for HPWH installations in new construction. Report focus areas included:

  • Determining if the recent 2019-2020 Washington Residential New Construction Code Study (NCCS) of the 2015 Washington state energy code residential provisions (WSEC-R) was a reasonable resource to inform NEEA’s understanding of HPWH adoption in Washington state new construction.
  • Completing a review of product incremental cost assumptions used in cost effectiveness calculations.
  • Determining if NEEA’s forecasted adoption of HPWHs identified as Tier 4 in the alliance’s Advanced Water Heating Specification appears reasonable given adoption rates of new tiers in prior years.

Findings from the review support the use of the 2019-2020 Washington Residential NCCS for updated estimates for Washington’s new homes market. In addition, findings support NEEA’s use and approach of baseline-adjusted Regional Technical Forum (RTF) measure values and weighting methodology to arrive at a regional average value and costs/ savings assumptions.

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