Multifamily Domestic Hot Water

Measure Description

The 2022 multifamily DHW distribution CASE measure would add a prescriptive requirement, change a mandatory requirement, and add a new compliance option. A summary of proposed changes includes:

• Submeasure A: Pipe Insulation Verification: Add a prescriptive requirement for field verification of pipe insulation quality
• Submeasures B: Increased Insulation: Increase stringency of existing mandatory pipe insulation thickness for pipes larger than two inches
• Submeasures C: CPC Appendix M Pipe Sizing: Add a compliance option for pipe sizing according to CPC Appendix M(IAPMO 2019)
• Change the existing prescriptive requirement for two recirculation loops in central DHW systems to a compliance option

All three proposed submeasures apply to new construction multifamily buildings with central water heating. None of the three proposed submeasures apply to additions or alterations. The Statewide CASE Team is still considering how best to reconcile the nonresidential and residential requirements that apply to hotel/motels and so did not analyze the impact of this measure on the hotel building prototype.

The proposed multifamily hot water distribution submeasures would reduce the energy budget of multifamily DHW recirculation systems by adding a new prescriptive requirement, increasing the stringency of an existing mandatory requirement, while reducing compliance barriers by changing an existing prescriptive requirement to a compliance option, and adding a new compliance option.

Submeasure A: Pipe Insulation Verification

This submeasure adds a prescriptive requirement for field verification of pipe insulation installation quality for DHW recirculation systems. Field verification would confirm installation of code required pipe insulation, including insulation on all fittings and valves, pumps, thermal isolation at pipe hangers, and overall insulation installation quality. This submeasure builds on the current single-family and low-rise multifamily residential pipe insulation inspection credit (PIC-H) and extends it to become a prescriptive baseline for all multifamily buildings with DWH recirculation systems. This submeasure includes minor updates to default values for derating insulation quality in the compliance software.

Submeasure B: Increased Insulation

This submeasure increases mandatory pipe insulation requirements for multifamily DHW pipes two inches and larger. This submeasure also aligns pipe insulation requirements for all multifamily buildings. This submeasure includes minor updates to default insulation thickness values in the compliance software.

Submeasure C: CPC Appendix M Sizing

This submeasure adds a compliance option for pipe sizing based on CPC Appendix M. Appendix M (IAPMO 2019) is an optional CPC appendix with an alternative pipe sizing procedure. Appendix M contains a performance-based pipe sizing calculation procedure that typically results in smaller pipe sizes than standard practice sizing, which results in lower first costs and distribution system heat loss. The current primary prescriptive baseline model assumes standard practice pipe sizing based on CPC Appendix A (fixture units, Hunter’s curve, etc.). This measure requires updates to the compliance software to include two pipe sizing approaches.

Change Existing Requirement for Two-Loop Recirculation Systems to a Compliance Option

The 2022 multifamily DHW distribution CASE measure would change the existing requirement for two recirculation loops in central DHW systems to a compliance option, while reducing the performance budget for multifamily DHW recirculation systems with new requirements in Submeasure A and B described above. This measure requires minor updates to the compliance software.

Central Heat Pump Water Heating

This measure will develop a prescriptive compliance pathway for central domestic water heating systems with heat pump technology serving multiple dwelling units by leveraging existing software algorithm development, lab testing, and design guide development. The Statewide CASE Team will perform additional market readiness research across a broad group of stakeholders and develop code and compliance manual language. This measure was initially included within the Multifamily Domestic Hot Water CASE report, but under advisement from the Energy Commission, the Statewide CASE Team moved to it to the Multifamily All Electric Package CASE Report.

Relevant Documents

Measure proposals, supporting documents, and other outside references will be made public as they become available.

• CASE Study Results Report – Multifamily Domestic Hot Water
• Final CASE Report – Multifamily Domestic Hot Water
• Draft CASE Report – Multifamily Domestic Hot Water
• 2019 New and Revised Multifamily Prototypes

Round Two Utility-Sponsored Stakeholder Meeting Materials

• Presentation – March 17 – Multifamily Water Heating and All Electric Package (Updated 4/13)
• Multifamily Hot Water Distribution Submeasure Summary
• Multifamily Drainwater Heat Recovery Submeasure Summary
• Multifamily Solar Thermal Submeasure Summary
• Multifamily All Electric Package Submeasure Summary (Updated 4/13)
• Notes – March 17 – Multifamily Water Heating and All Electric Package

Round One Utility-Sponsored Stakeholder Meeting Materials

• Presentation – Aug. 22 – Multifamily HVAC and Envelope Utility-Sponsored Stakeholder Meeting
• Presentation – Oct. 3 – Multifamily and Nonresidential Water Heating Utility-Sponsored Stakeholder Meeting
• Multifamily Hot Water Distribution Submeasure Summary – October 2, 2019
• Multifamily Solar Thermal Submeasure Summary – August 22, 2019
• Multifamily Drain Water Heat Recovery Submeasure Summary – August 22, 2019
• Notes – Oct. 3 – Multifamily and Nonresidential Water Heating