ASHRAE-90.1-2022- - Page 192

Extracted Content

credit. Buildings where the installed service water heating capacity is less than 200,000 Btu/h and weighted UEF is not less than 0.82 shall achieve 25% of the base table W03 credit. d. Combination service water heating systems shall achieve credits as follows:

1. (W01 + W02) Where service water heating employs both energy recovery and heat-pump water heating, W01 is permitted to be combined with W02 and receive the sum of both credits.
2. (W01 + W03) Where service water heating employs both energy recovery and efficient gas water heating, W01 is permitted to be combined with W03 and receive the sum of the W01 credit and the portion of the W03 credit based on item (4).
3. (W02 + W03) Where service water heating employs both heat-pump water heating and efficient gas water heating, W02 is permitted to be combined with W03 and receive the sum of the W02 credit and the portion of the W03 credit based on item (4).
4. For items (2) and (3), the portion of W03 credit shall be the Section 11.5.3 W03 credit multiplied by the share of total water heating installed capacity served by gas water heating with not less than 95% Et or 0.93 UEF. In no case shall it exceed 60% of the W03 credit in Section 11.5.3. In buildings that have a service water heating design generating capacity greater than 900,000 Btu/h, that proportioned W03 credit shall be further multiplied by 29.6%. 11.5.2.3.2 W04: Service Hot-Water Piping Insulation Increase. To achieve this credit, where service hot water is provided by a central water heating system, the hot-water pipe insulation thickness shall be at least 1.5 times the thickness required in Table 6.8.3-1. All service hot-water piping shall be insulated from the hot-water source to the fixture shutoff. Where no more than 50% of hot-water piping does not have increased insulation due to installation in partitions, the credit shall be prorated as a percentage of lineal feet of piping with increased insulation.

11.5.2.3.3 Improved Service Hot-Water Temperature Maintenance. To achieve this credit, hotwater distribution temperature maintenance shall comply with one of the following:

a. W05: Point-of-Use Water Heater. Credits are available for office or school buildings larger than 10,000

ft [2] . Fixtures requiring hot water shall be supplied from a localized source of hot water with no recirculating system or heat trace piping . Supply piping from the water heater to the termination of the fixture supply pipe shall be insulated to the levels shown in Table 6.8.3-1 without exception. The volume from the water heater to the termination of the fixture supply pipe shall be limited as follows:

1. Nonresidential lavatories: not more than 2 oz
2. All other plumbing fixtures or appliances: not more than 0.25 gal Exception to 11.5.2.3.3(a): Where all remotely located hot-water uses meet the requirements for mea sure W05, separate water heater s serving commercial kitchens or showers in locker rooms shall be permitted to have a local recirculating system or heat trace piping . b. W06: Thermostatic Balancing Valves. Credits are available where service water heating is provided

centrally and distributed throughout the building . Each recirculating system branch return connection to the main service hot-water supply piping shall have an automatic thermostatic balancing valve set to a minimal return water flow when the branch return temperature is greater than 125  F.

11.5.2.3.4 W07: Dwelling-Unit Service Hot-Water Submeters. To achieve this credit, each individual dwelling unit in a multifamily building served by a central service water heating system shall be provided with a service hot-water meter connected to a reporting system that provides individual dwelling unit reporting of actual domestic hot-water use. Recording of preheated water serving the cold water inlet to showers need not be metered.

11.5.2.3.5 W08: Right Sizing the Service Hot-Water Distribution System. To achieve this credit, where multifamily, dormitory, retirement, or hotel/motel buildings are served by a central service hot-water system, the distribution system serving dwelling units and guest rooms shall be sized using IAPMO/ANSI WE•Stand, Appendix C. Plumbing fixtures in residential spaces that are connected to the service water heat- ing system shall have a flow or consumption rating less than or equal to the values shown in Table 11.5.2.3.5.

Informative Note: Where low water supply pressures are anticipated, user satisfaction may be enhanced if flow restrictors are specified to provide ≥80% of the rated flow at 20 psi. Where the distribution sizing protocol is applied to other than multifamily residential buildings, a variance to the plumbing code may be needed.

11.5.2.3.6 W09: Shower Drain Heat Recovery. To achieve this credit, cold water serving building showers shall be preheated by shower drain heat recovery units that comply with CSA B55.2. Potable waterside pressure loss shall be less than 10 psi at maximum design flow. The efficiency of drain heat recovery units shall be 54% or greater measured in accordance with CSA B55.1. Full credits are applicable to the fol

190 ANSI/ASHRAE/IES Standard 90.1-2022 (I-P)