ASHRAE-90.1-2022- - Page 315

Extracted Content

Table G3.1 Modeling Requirements for Calculating Proposed Building Performance and Baseline Building Performance (Continued)

Proposed Building Performance	Baseline Building Performance
14. Exterior Conditions (continued)
c. Water Main Temperatures for Service Water-Heating Calcu- lations. It is acceptable to use either an annual water main supply temperature or monthly average water main supply temperatures for calculating service water heating. If annual or monthly water main supply temperatures are not available from the local water utility, annual average ground temperatures may be used.
15. Distribution Transformers
Low-voltage dry-type distribution transformers shall be modeled if the transformers in the proposed design exceed the efficiency required in Table 8.4.4.	Low-voltage dry-type distribution transformers shall be modeled only if the proposed design transformers exceed the efficiency requirements of Table 8.4.4. A transformer with a kVA rating not listed in the table shall have its minimum efficiency level calculated by a linear interpolation of the kVA and efficiency values listed in the table immediately above and below its kVA rating. If modeled, the efficiency requirements from Table 8.4.4 or the interpolated efficiency requirements shall be used. The ratio of the capacity to peak electrical load of the transformer shall be the same as the ratio in the proposed design.
16. Elevators
Where the proposed design includes elevators, the elevator motor, ventilation fan, and light load shall be included in the model. The cab ventilation fan and lights shall be modeled with the same schedule as the elevator motor.	Where the proposed design includes elevators, the baseline building design shall be modeled to include the elevator cab motor, ventilation fans, and lighting power. The elevator peak motor power shall be calculated as follows: bhp = (Weight of Car + Rated Load – Counterweight) × Speed of Car/(33,000 × hmechanical) Pm = bhp × 746/hmotor where Weight of Car = the proposed design elevator car weight, lb Rated Load = the proposed design elevator load at which to operate, lb Counterweight of Car = the elevator car counterweight, from Table G3.9.2, lb Speed of Car = the speed of the proposed elevator, ft/min hmechanical = the mechanical efficiency of the elevator from Table G3.9.2 hmotor = the motor efficiency from Table G3.9.2 Pm = peak elevator motor power, W The elevator motor use shall be modeled with the same schedule as the proposed design. When included in the proposed design, the baseline elevator cab ventilation fan shall be 0.33 W/cfm and the lighting power density shall be 3.14 W/ft2; both operate continuously.
17. Refrigeration
Where refrigeration equipment in the proposed design is rated in accordance with AHRI 1200, the rated energy use shall be modeled. Otherwise, the proposed design shall be modeled using the actual equipment capacities and efficiencies.	Where refrigeration equipment is specified in the proposed design and listed in Tables G3.10.1 and G3.10.2, the baseline building design shall be modeled as specified in Tables G3.10.1 and G3.10.2 using the actual equipment capacities. If the refrigeration equipment is not listed in Tables G3.10.1 and G3.10.2, the baseline building design shall be modeled the same as the proposed design.
18. On-Site Renewable Energy
On-site renewable energy in the proposed building performance shall be determined as follows: a. Where a complete system providing on-site renewable energy exists, the model shall reflect the actual system type using actual component capacities and efficiencies. b. Where a system providing on-site renewable energy has been designed, the system model shall be consistent with design documents. c. Where no system exists or is specified to provide on-site renewable energy, no system shall be modeled.	On-site renewable energy shall not be included in the baseline building performance.