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Measure Description

The drain water heat recovery (DWHR) measure is completely new in the California Energy Code, and saves water heating energy expended during showering. This measure applies to new construction of low-rise residential buildings. DWHR is likely cost-effective in some high-rise residential and some nonresidential applications (e.g. hotel laundry rooms), but only the new construction low-rise residential section of the standards will be modified. In addition, only savings from showering will be modeled in the residential energy software. DWHR comes in horizontal and vertical configurations, but only vertical units are included in this measure, because there is currently no performance testing standard for horizontal units. IAMPO and a horizontal manufacturer are currently working on such a standard, which the manufacturer expects to be completed in July 2017 and titled IAPMO IGC-346.


The Statewide CASE Team 2019 Title 24, Part 6 Final CASE Report is available below. The Final CASE Report incorporates feedback received during utility-sponsored stakeholder meetings, Energy Commission Pre-Rulemaking workshops, and personal communication with stakeholders.

Presentations and Meetings

  1. Presentation from Stakeholder Meeting on October 26, 2016
  2. Notes from Stakeholder Meeting on October 26, 2016
  3. Presentation from Stakeholder Meeting on March 23, 2017
  4. Notes from Stakeholder Meeting on March 23, 2017

Code Language

  1. Draft Code Language, March 2017


  1. ETCC Report: Development of a Laboratory Data-Based Algorithm for Horizontal Drain Water Heat Recovery Devices, and Predictions of In-Field Performance
  2. Development of a Title 24 Compliance Model for Residential Drain Water Heat Recovery Devices
  3. Results of Vertical Drain Water Heat Recovery Phase Two Lab Testing and Data Analysis


  1. CASE Study Results Report
  2. Final CASE Report
  3. Draft CASE Report

Give Us Your Feedback

The Statewide CASE Team values input from all stakeholders engaged in the Title 24, Part 6 code change process. We encourage the open exchange of code change comments and concerns.

  • Use the form above to provide feedback on this measure.

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