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Drain Water Heat Recovery

Residential Water Heating

Codes and Standards Enhancement (CASE) Report

The Statewide CASE Team is requesting feedback on the 2019 Title 24, Part 6 Draft CASE Reports. The CASE Report presents pertinent information that supports the code change proposal. Please email feedback to You may also submit written comments to the Energy Commission. See the agenda for Energy Commission pre-rulemaking workshop (available here) for instructions on how to submit comments to the Energy Commission’s docket.

Draft CASE Report: Residential Drain Water Heat Recovery

Measure Description

The drain water heat recovery (DWHR) measure is completely new in the California Building Energy Efficiency Standards, 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.

Request for Feedback

The Statewide Utility Team encourages participation in the CASE Report development process through the submission of data—both primary sources and references to existing data. We are requesting data on areas such as energy savings, costs, market impacts, industry practices, barriers to code compliance, etc. from stakeholders. The data will inform the energy savings estimates, cost-effectiveness analysis, compliance and enforcement, and market impacts that will be presented in CASE Reports.

Do you have feedback or data to share? Send us an email at

California Statewide Utility Codes and Standards Program

This program is funded by California utility customers and administered by Pacific Gas and Electric Company, Southern California Edison, San Diego Gas and Electric Company, Southern California Gas Company, Sacramento Municipal District, and Los Angeles Department of Water and Power in preparation for the California Energy Commission’s Codes and Standards Buildings Advocacy.