ASHRAE-90.1-2022- - Page 157

Extracted Content

2. The photocontrol shall reduce electric lighting power in response to available daylight using continu- ous daylight dimming to 20% or less and off.

3. When an automatic reduction control has reduced the lighting power to the unoccupied set point in accordance with Section 9.4.1.1(g), the daylight responsive control shall adjust the electric light in response to available daylight, but it shall not allow the lighting power to be above the unoccupied set point . Exceptions to 9.4.1.1(e): The following areas are exempted from Section 9.4.1.1(e):

4. Primary sidelighted areas where the top of any existing adjacent structure or natural object is at least twice as high above the windows as its horizontal distance away from the windows.

5. Sidelighted areas where the total glazing area is less than 20 ft [2] .

6. Primary sidelighted areas adjacent to vertical fenestration that have external projections and no vertical fenestration above the external projection, where the external projection has a projection factor greater than 1.0 for north-oriented projections or where the external projection has a pro- jection factor greater than 1.5 for all other orientations (see Figure 3.2-6). f. Automatic daylight responsive controls for toplighting : In any space where the combined input power for all general lighting completely or partially within daylight area under skylights and daylight area under roof monitors is 75 W or greater, general lighting in the daylight area shall be controlled by photocontrols. The control system shall have the following characteristics:

7. The calibration adjustment control shall be located no higher than 11 ft above the finished floor . Calibration shall not require the physical presence of a person at the sensor while it is processing.

8. The photocontrol shall reduce lighting power in response to available daylight using continuous day- light dimming to 20% or less and off.

9. When an automatic reduction control has reduced the lighting power to the unoccupied set point in accordance with Section 9.4.1.1(g) the daylight responsive control shall adjust the electric light in response to available daylight, but it shall not allow the lighting power to be above the unoccupied set point .

10. General lighting in overlapping toplighted and sidelighted daylight areas shall be controlled together with general lighting in the daylight area under skylights or daylight area under roof monitors . Exceptions to 9.4.1.1(f): The following areas are exempted from Section 9.4.1.1(f):

11. Daylight area under skylights where it is documented that existing adjacent structures or natural objects block direct sunlight for more than 1500 daytime hours per year between 8 a.m. and 4 p.m.

12. Daylight area under skylights where the overall skylight effective aperture for the enclosed space is less than 0.006.

13. In each space within buildings in Climate Zone 8 where the input power of the general lighting within daylight areas is less than 200 W. g. Automatic reduction control (full OFF complies): The general lighting power in the space shall be auto-

matically reduced by at least 50% within 20 minutes of all occupants leaving the space .

In offices greater than 300 ft [2], control zones for general lighting shall

1. be limited to 600 ft [2] and
2. automatically reduce general lighting by at least 80% of full power within 20 minutes of all occupants leaving a control zone. h. Automatic full OFF control: All lighting in the space, including lighting connected to emergency circuits,

shall be automatically shut off within 20 minutes of all occupants leaving the space . A control device meeting this requirement shall control no more than 5000 ft [2] . Exceptions to 9.4.1.1(h): The following lighting is not required to be automatically shut off:

1. Lighting required for 24/7 continuous operation.
2. Lighting in spaces where patient care is rendered.
3. General lighting and task lighting in spaces where automatic shutoff would endanger the safety or security of the room or building occupants.
4. Lighting load not exceeding 0.02 W/ft [2] multiplied by the gross lighted floor area of the building . i. Scheduled shutoff : All lighting in the space, including lighting connected to emergency circuits, shall be automatically shut off during periods when the space is scheduled to be unoccupied using either (1) a time-of-day operated control device that automatically turns the lighting off at specific programmed times or (2) a signal from another automatic control device or alarm/security system . The control device or system shall provide independent control sequences that (1) control the lighting for an area of no more than 25,000 ft [2], (2) include no more than one floor, and (3) shall be programmed to account for weekends and holidays. Any manual control installed to provide override of the scheduled shutoff control

ANSI/ASHRAE/IES Standard 90.1-2022 (I-P) 155