ASHRAE-90.1-2022- - Page 376
Extracted Content
L2.1.2 Mechanical System Performance Rating Method Requirements. All HVAC systems using the Mechanical System Performance Rating Method shall demonstrate compliance using TSPRp and TSPRr in accordance with Section 6.6.2 and the following requirements:
a. TSPRp and TSPRr shall be calculated in accordance with Section L2.1.5, “Calculating TSPR, ” and the
requirements of Sections L1, L3, L4, and L5. b. Alterations that include replacement of the entire HVAC system shall be modeled as a new building . c. HVAC systems shall comply with Section L2.1.4 “Partial Prescriptive Requirements.” d. Initial build-out construction shall be modeled in accordance with Section L2.1.3, “Core and Shell/Initial
Build-Out Construction Analysis.” e. Compliance documentation and supplemental information shall be submitted in accordance with Sec tions 4.2.2 and L2.1.6 “ TSPR Submittals.”
L2.1.3 Core and Shell/Initial Build-Out Construction Analysis. Where the building permit applies to only a portion of the HVAC system in a building, and the remaining components will be designed under a future building permit or were previously installed, the future or previously installed components shall be modeled as follows:
a. Where the HVAC zones that do not include HVAC systems in the current permit will be or are served by
independent systems, the block (see Section L2.2.1) including those zones shall not be included in the model. b. Where the HVAC zones that do not include complete HVAC systems in the permit are intended to receive
HVAC services from systems in the permit, their proposed zonal systems shall be modeled with equip- ment that meets but does not exceed the requirements of Sections 6.4 and 6.5. c. Where the zone equipment in the permit receives HVAC services from previously installed systems that
are not in the permit, the previously installed systems shall be modeled with equipment matching the certified value of what is installed or equipment that meets the requirements of Sections 6.4 and 6.5, whichever has the more efficient energy use. d. Where the central plant heating and cooling equipment is completely replaced and HVAC zones with
existing systems receive HVAC services from systems in the permit, their proposed zonal systems shall be modeled with equipment that meets but does not exceed the requirements of Sections 6.4 and 6.5. Informative Notes:
- Examples of HVAC systems that are intended to receive HVAC services from systems in the permit include future zonal water source heat pumps that will receive loop water that is heated by a boiler or is cooled by a cooling tower included in the permit, any system that will receive outdoor ventilation air from a DOAS included in the permit, and future zone terminal units that will be connected to a central VAV system included in the permit.
- An initial build-out with heating coils served from a previously installed system with a high_efficiency_ condensing boiler would use the installed efficiency if it exceeded the current requirements. If the installed boiler had a lower efficiency than the current requirements, the current requirement would be used.
- A partial central plant upgrade (e.g., chiller but not boiler replacement) cannot use this method.
L2.1.4 Partial Prescriptive Requirements. HVAC systems using the HVAC Performance Rating Method shall meet relevant prescriptive requirements in Section 6.5 as follows:
a. Air economizers shall meet the requirements of Sections 6.5.1.1.5 and 6.5.1.1.6. b. Steam humidifiers shall meet requirements of Section 6.5.2.4. c. Variable-air-volume systems shall meet requirements of Sections 6.5.3.2.2, 6.5.3.2.3, and 6.5.3.3. d. Hydronic systems shall meet the requirements of Section 6.5.4.2. e. Plants with multiple chillers or boiler s shall meet the requirements of Section 6.5.4.3. f. Chilled-water and heating-water supply temperature reset shall meet the requirements of Section 6.5.4.4 without exception. g. Hydronic (water loop) heat pumps and water-cooled unitary air conditioners shall meet the requirements
of Section 6.5.4.5. h. Cooling-tower turndown shall meet the requirements of Section 6.5.5.4. i. Heating of unenclosed spaces shall meet the requirements of Section 6.5.8.1. j. Hot-gas bypass shall meet the requirements of Section 6.5.9. k. Systems shall meet the door switch control requirements of Section 6.5.10. l. Refrigeration systems shall meet the requirements of Section 6.5.11.
374 ANSI/ASHRAE/IES Standard 90.1-2022 (I-P)