ASHRAE-90.1-2022- - Page 080

Extracted Content

6.4.3.3.5 Automatic Control of HVAC in Hotel/Motel Guest Rooms. Hotels and motels with greater than 50 guest rooms shall be provided with automatic controls for the HVAC equipment serving each guest room capable of and configured according to the requirements in the following subsections.

6.4.3.3.5.1 Guest Room HVAC Set-Point Control. HVAC systems serving hotel guest rooms shall be capable of and configured with three modes of temperature control.

a. Rented and unoccupied. Within 20 minutes of all occupants leaving the guest room, HVAC set points

shall be automatically raised by at least 4°F from the occupant set point in the cooling mode and auto- matically lowered by at least 4°F from the occupant set point in the heating mode. b. Unrented and unoccupied. HVAC set points shall be automatically reset to 80°F or higher in the cool ing mode and to 60°F or lower in the heating mode. The HVAC set points in the unrented and unoccupied guest room modes shall be initiated within 16 hours of the guest room being continuously unoccupied or within 20 minutes of the guest room being continuously unoccupied where a networked guest room control system indicates the guest room is unrented. c. Occupied. HVAC set points shall return to their occupied set points once occupancy is sensed.

Exceptions to 6.4.3.3.5.1:

1. A networked guest room control system shall be permitted to return the thermostat set points to their default occupied set points 60 minutes prior to the time the room is scheduled to be occupied.
2. Dehumidification shall be permitted to limit the space humidity levels as required by Standard 62.1 during unoccupied mode for both rented and unrented periods.

6.4.3.3.5.2 Guest Room Ventilation Control. Within 20 minutes of all occupants leaving the guest room, ventilation and exhaust fans shall automatically be turned off, or isolation devices serving each guest room shall automatically shut off the supply of outdoor air to the guest room and shut off exhaust air from the guest room.

Exception to 6.4.3.3.5.2: Guest room ventilation systems shall be permitted to have an automatic

daily preoccupancy purge cycle that provides daily outdoor air ventilation during unrented periods at the design ventilation rate for 60 minutes, or at a rate and duration equivalent to one air change.

6.4.3.4 Ventilation System Controls 6.4.3.4.1 Stair and Elevator Shaft Vent Dampers. Where stair and elevator shafts have vents, they shall be equipped with motorized dampers that are capable of and configured to automatically close during normal building operation and are interlocked to open as required by fire and smoke detection systems or by thermostatic control systems .

Exception to 6.4.3.4.1: Nonmotorized gravity backdraft dampers are acceptable in buildings less than

three stories in height and for buildings of any height located in Climate Zones 0, 1, 2, and 3.

6.4.3.4.2 Shutoff Damper Controls. All outdoor air intake and exhaust systems shall be equipped with motorized dampers that will automatically shut when the systems or spaces served are not in use. Out- door air and exhaust/relief dampers shall be capable of and configured to automatically shut off during preoccupancy building warm-up, cooldown, and setback, except when the supply of outdoor air reduces energy costs or when outdoor air must be supplied to meet code requirements.

Exceptions to 6.4.3.4.2:

1. Nonmotorized (gravity backdraft) dampers are acceptable for exhaust and relief in buildings less than three stories in height and for outdoor air intakes and exhaust and relief dampers in buildings of any height located in Climate Zones 0, 1, 2, and 3. Nonmotorized dampers for out- door air intakes must be protected from direct exposure to wind.
2. Nonmotorized dampers are acceptable in systems with a design outdoor air intake or exhaust capacity of 300 cfm or less.
3. Dampers are not required in ventilation or exhaust systems serving unconditioned spaces .
4. Dampers are not required in exhaust systems serving Type 1 kitchen exhaust hoods.
5. Dampers are not required in systems intended to operate continuously.

6.4.3.4.3 Damper Leakage. Where outdoor air supply and exhaust/relief dampers are required by Section 6.4.3.4.1, they shall have a maximum leakage rate as indicated in Table 6.4.3.4.3.

6.4.3.4.4 Ventilation Fan Controls. Fans with motors greater than 0.75 hp shall have automatic con- trols complying with Section 6.4.3.3.1 that are capable of and configured to shut off fans when not required.

Exception to 6.4.3.4.4: HVAC systems intended to operate continuously.

78 ANSI/ASHRAE/IES Standard 90.1-2022 (I-P)