ASHRAE-90.1-2022- - Page 190
Extracted Content
Table 11.5.2.2.6 DOAS Energy Recovery Adjustments
ERE adj Based on Lower of Actual Heating or Cooling Energy Recovery Effectiveness where Required
| Cooling ERR Is ≥ | Heating Enthalpy Recovery Ratio (ERR) or Sensible Energy Recovery Ratio Is ≥ | Energy Recovery Effectiveness Adjustment (ERE ) adj |
|---|---|---|
| 65% | 65% | 1.00 |
| 60% | 60% | 0.67 |
| 55% | 55%a | 0.33 |
| 50% | 50% a | 0.25 |
a. In climate zones where heating recovery is required for this measure, for multifamily buildings heating energy recovery effectiveness below 60% is not
allowed.
analysis approved by the authority having jurisdiction . Heat rejection shall include a two-speed or variable-speed fan.
The allowed credits are based on serving 25% of gross conditioned building area and including dry-cooler partial heat rejection. Adjust the base credits as follows:
= EC H05 _ base ------------------------0.25 HR adj
EC H05 _ adj = EC H05 _ base
Floor GSHP
where EC H05_adj = energy credits achieved for ground-source heat-pump system EC H05_base = H05 base energy credit from Section 11.5.3 Floor GSHP = fraction of whole-project gross conditioned floor area with heating and cooling provided by the ground-source heat pump. HR adj = heat-rejection adjustment factor by climate zone from Table 11.5.2.2.5 11.5.2.2.6 H06: Dedicated Outdoor Air System with Zone Fan Control. Credits for this measure are only allowed where single-zone HVAC units are not required to have multispeed or variable-speed fans in accordance with Section 6.5.3.2.1. HVAC controls and ventilation systems shall include all of the following:
a. Zone controls shall cycle the heating/cooling-unit fans off when not providing required heating and cool ing or shall limit fan power to 0.12 W/cfm of air delivered to the zone by the unit. b. Outdoor air shall be supplied by an independent ventilation system designed to provide no more than
110% of the minimum outdoor air to each individual occupied space as specified by Standard 62.1 c. The ventilation system shall have energy recovery with an enthalpy recovery ratio ( ERR ) of 65% or more
at heating design conditions in Climate Zones 3 through 8 and an ERR of 65% or more at cooling design conditions in Climate Zones 0, 1, 2, 3A, 3B, 4A, 4B, 5A, and 6A. In “A” climate zones, energy recovery shall include latent recovery. Where no humidification is provided, heating energy recovery effectiveness is permitted to be based on sensible energy recovery ratio . Where energy recovery effectiveness is less than the 65% required for full credit, adjust the credits from Section 11.5.3 by the factors in Table 11.5.2.2.6. d. Where the ventilation system serves multiple zones, partial economizer cooling through an outdoor air
bypass shall automatic ally reset the energy recovery leaving air temperature at 55 F or 100% outdoor air bypass when a majority of zones require cooling and outdoor air temperature is below 70 F. Recoverywheel speed control or other means are permitted to allow partial economizer cooling. Partial economizer cooling is not required in a latent recovery outdoor air dehumidification mode. e. Ventilation systems providing mechanical dehumidification shall use recovered energy for reheat within
the limits of item (d). This shall not limit the use of latent energy recovery for dehumidification.
Where only a portion of the building is served by constant-air-volume (CAV) units or the ERR or sensi- ble energy recovery ratio is less than 65%, the base energy credit shown in Section 11.5.3 shall be prorated as follows:
EC H06 _ adj = EC H06 _ base Floor CAV ERE adj
where EC H06_adj = energy credits achieved for dedicated outdoor air system with zone fan control EC H06_base = H06 base energy credit from Section 11.5.3
188 ANSI/ASHRAE/IES Standard 90.1-2022 (I-P)