ASHRAE-90.1-2022- - Page 217

Extracted Content

Table 12.5.1 Modeling Requirements for Calculating Design Energy Cost and Energy Cost Budget

Proposed Design (Column A) Design Energy Cost (DEC)	Budget Building Design (Column B) Energy Cost Budget (ECB)
1. Design Model
The simulation model of the proposed design shall be consistent with the design documents, including proper accounting of fenestration and opaque envelope types and area; interior lighting power and controls; HVAC system types, sizes, and controls; and service water-heating systems and controls. All conditioned spaces in the proposed design shall be simulated as being both heated and cooled, even if no cooling or heating system is being installed. Temperature and humidity control set points and schedules, as well as temperature control throttling range, shall be the same for proposed design and baseline building design. When the Energy Cost Budget Method is applied to buildings in which energy-related features have not yet been designed (e.g., a lighting system), those yet-to-be-designed features shall be described in the proposed design so that they minimally comply with applicable mandatory and prescriptive requirements from Sections 5 through 10. Where the space classification for a building is not known, the building shall be categorized as an office building.	The budget building design shall be developed by modifying the proposed design as described in this table. Except as specifically instructed in this table, all building systems and equipment shall be modeled identically in the budget building design and proposed design.
2. Additions and Alterations
It is acceptable to demonstrate compliance using building models that exclude parts of the existing building, provided all of the following conditions are met: Work to be performed under the current permit application in excluded parts of the building shall meet the requirements of Sections 5 through 10. Excluded parts of the building are served by HVAC systems that are entirely separate from those serving parts of the building that are included in the building model. Design space temperature and HVAC system operating set points and schedules on either side of the boundary between included and excluded parts of the building are identical. If a declining block or similar utility rate is being used in the analysis and the excluded and included parts of the building are on the same utility meter, the rate shall reflect the utility block or rate for the building plus the addition.	Same as proposed design.
3. Space Use Classification
The building area type or space type classifications shall be chosen in accordance with Section 9.5.1 or 9.5.2. The user or designer shall specify the space use classifications using either the building area type or space type categories but shall not combine the two types of categories within a single permit application. More than one building area type category may be used for a building if it is a mixed-use facility. Exception: Where space types neither exist nor are designated in design documents, use type shall be specified in accordance with Section 9.5.1.	Same as proposed design.
4. Schedules
The schedule types listed in Section 12.4.1.1(b) shall be required input. The schedules shall be typical of the proposed design as determined by the designer and approved by the authority having jurisdiction. Required schedules shall be identical for the proposed design and budget building design. Temperature and Humidity Schedules. Temperature and humidity control set points and schedules, as well as temperature control throttling range, shall be the same for proposed design and baseline building design. HVAC Fan Schedules. Schedules for HVAC fans that provide outdoor air for ventilation shall run continuously whenever spaces are occupied and shall be cycled ON and OFF to meet heating and cooling loads during unoccupied hours. Exceptions: Where no heating and/or cooling system is to be installed, and a heating or cooling system is being simulated only to meet the requirements described in this table, heating and/or cooling system fans shall not be simulated as running continuously during occupied hours but shall be cycled ON and OFF to meet heating and cooling loads during all hours.	Same as proposed design.