ASHRAE-90.1-2022- - Page 306
Extracted Content
design energy consumption prior to calculating the proposed building performance, provided that the building owner
a. owns the on-site renewable energy system or b. has signed a lease agreement for the on-site renewable energy system for at least 15 years or c. has signed a contractual agreement to purchase energy generated by the on-site renewable energy system
for at least 15 years.
G2.4.2 Annual Energy Costs. The design energy cost and baseline energy cost shall be determined using either actual rates for purchased energy or state average energy prices published by U.S. DOE’s Energy Information Administration (EIA) for commercial building customers, but rates from different sources may not be mixed in the same project. Where on-site renewable energy or site-recovered energy is used, the base- line building design shall be based on the energy source used as the backup energy source, or the baseline system energy source in that category if no backup energy source has been specified, except where the baseline energy source is prescribed in Tables G3.1.1-2 and G3.1.1-3. Where the proposed design includes on- site electricity generation systems other than on-site renewable energy systems, the baseline design shall include the same generation systems excluding its site-recovered energy .
Informative Note: The above provision allows users to gain credit for features that yield load management benefits. Where such features are not present, users can simply use state average unit prices from EIA, which are updated annually and readily available on EIA’s website (www.eia.gov).
G2.5 Exceptional Calculation Methods. When the simulation program does not model a design, material, or device of the proposed design, an exceptional calculation method shall be used as approved by the rating authority . Where there are multiple designs, materials, or devices that the simulation program does not model, each shall be calculated separately and exceptional savings determined for each. At no time shall the total exceptional savings constitute more than half of the difference between the baseline building perfor- mance and the proposed building performance . All applications for approval of an exceptional method shall include the following:
a. Theoretical and empirical information verifying the method’s accuracy, and step-by-step documentation
of the exceptional calculation method performed, detailed enough to reproduce the results. b. Copies of all spreadsheets used to perform the calculations. c. A sensitivity analysis of energy consumption when each of the input parameters that are estimated is var ied from half to double the value assumed. d. The calculations shall be performed on a time-step basis consistent with the simulation program used. e. The Performance Cost Index calculated with and without the exceptional calculation method.
G3. CALCULATION OF THE PROPOSED DESIGN AND BASELINE BUILDING PERFORMANCE
G3.1 Building Performance Calculations
G3.1.1 Scope. The simulation model for calculating the proposed building performance and baseline building performance shall be developed in accordance with Sections G3.1.2, G3.1.3, or G3.1.4 as applicable.
G3.1.2 New Buildings. The simulation model for calculating the proposed building performance and baseline building performance for new buildings shall be developed in accordance with the requirements in Section G3.2.
G3.1.3 Additions. The simulation model for calculating the proposed building performance and baseline building performance for additions shall be developed in accordance with the requirements in Section G3.2.
G3.1.4 Alterations. The simulation model for calculating the proposed building performance and base- line building performance for alterations, excluding additions, shall be developed in accordance with the applicable subparagraph (a) or (b).
a. In accordance with Section G3.2 for alterations that include replacement of two or more of the following:
- HVAC systems that account for more than 50% of the capacity serving either the heating or cooling loads of the alteration area. This includes HVAC unitary systems, HVAC terminal units, or components of HVAC central heating or cooling equipment . HVAC terminal units, for the purposes of this section, can include VAV boxes, fan-coil units, VRF room units, or water-loop heat pumps;
- 50% or more of the luminaires in the alteration area;
- 25% or more of the building envelope area of the alteration portion of the building, including new exterior cladding, fenestration, or insulation. b. In accordance with Section G3.3 for all other alterations.
304 ANSI/ASHRAE/IES Standard 90.1-2022 (I-P)