ASHRAE-90.1-2022- - Page 191
Extracted Content
Floor CAV = fraction of whole-project gross conditioned floor area where constant-air-volume singlespeed fans are allowed and meet measure requirements
ERE adj = energy recovery adjustment from Table 11.5.2.2.6 based on the lower of actual cooling or heating ERR or sensible energy recovery ratio where required for the climate zone
11.5.2.2.7 H07: Improved HVAC Sequence of Operations. To achieve this credit, all applicable control sequences shall be based on ASHRAE Guideline 36. Credits for this measure are only allowed where the HVAC system includes at least one of the following: a VAV air handler serving at least five (5) zone terminals, a chilled-water plant with at least two chillers, or a hot-water plant with at least two boilers or heat pumps.
11.5.2.3 Reduced Energy Use in Service Water Heating. Energy credits described in Section 11.5.2.3.1 through 11.5.2.3.6 are available in any combination described in those sections for building use types where base credits are included in Section 11.5.3 tables.
11.5.2.3.1 Improved Service Water Heating Effectiveness. Service water heating effectiveness energy credits are permitted to be achieved in building use types where credits are available in Section 11.5.3 for one of the following:
a. W01: Heat Recovery for Service Hot-Water Preheating. To achieve this credit, the service water
heating system shall have waste heat recovery from service hot water, heat recovery chillers, building equipment, or process equipment that is sized to provide not less than 30% of the annual hot-water requirements or sized to provide not less than 70% of the annual hot-water requirements if the building is required to comply with Section 7.5.3. b. W02: Heat-Pump Water Heater. To achieve this credit, air source heat-pump water heater s shall be
installed according to the manufacturer ’s instructions, and at least 30% of design end-use service water heating requirements shall be met using only heat-pump heating at an ambient condition of 67.5°F db without supplemental electric resistance or fossil fuel heating. For a hybrid heat-pump water heater, the heat-pump-only capacity shall be deemed at 40% of first hour draw. Where the heat-pump-only capacity exceeds 50% of the design end-use load, excluding recirculating system losses, the credits from the Section 11.5.3 tables shall be prorated as follows:
EC W02 _ calc = EC W02 _ base -----------------------------------EndLoadCap HPWH 0.5 not greater than 2
where
EC W02_calc = energy credits achieved for heat-pump water heater
EC W02_base = W02 base energy credit from Section 11.5.3 Cap HPWH = heat-pump-only capacity at 50 F entering air and 70 F without supplemental electric resistance or fossil fuel heat, Btu/h
EndLoad = end-use peak hot-water load, excluding load for heat trace or recirculation, Btu/h
The heat-pump service water heating system shall comply with the following requirements:
- For central systems with an installed total output capacity of more than 100,000 Btu/h at an ambient condition of 67.5 F db, a preheat storage tank with ≥0.75 gal per 1000 Btu/h of design end-use ser- vice water heating requirements shall be heated only with heat-pump heating when the ambient temperature is >45 F.
- For systems with piping temperature maintenance, either a heat trace system or a separate water heater in series for recirculating system and final heating shall be installed.
- Heat-pump water heater efficiency shall meet or exceed one of the following: i. Output-capacity-weighted-average uniform energy factor (UEF) of 3.0 with a medium draw pattern in accordance with 10 CFR 430 Appendix E. ii. Output-capacity-weighted-average COP of not less than 4.0 tested at 50 F entering air and 70 F
entering water in accordance with AHRI Standard 1300. Informative Note: Service water heating system control settings and operating temperatures should be determined in accordance with the ASHRAE Standard 188 building water systems water management program for the building or with generally accepted engineering standards and guidance (e.g., ASHRAE Guideline 12). c. W03: Efficient Gas Water Heater. To achieve this credit, the combined input-capacity-weighted-average
equipment rating of all gas water heating equipment in the building shall be not less than 95% Et or 0.93 UEF. Buildings required to comply with Section 7.5.3 shall receive 29.6% of the Section 11.5.3 W03
ANSI/ASHRAE/IES Standard 90.1-2022 (I-P) 189