Washington Administrative Code › Title 51 - Enterprise Services, Department of (Building Code Council) › Chapter 51-11C - State Building Code adoption and amendment of the 2021 edition of the International Energy Conservation Code, Commercial › Section 51-11C-405025 - Section C405.2.5- Daylight responsive controls

Current through Register Vol. 24-14, July 15, 2024
C405.2.5
Daylight
			 responsive controls.
Daylight responsive controls
complying with Section C405.2.5.1 shall be provided to control the
general lighting
within
daylight zones
in the
			 following spaces:
1. Spaces with a total of
			 more than 75 watts of
general lighting
within
primary
			 sidelit daylight zones
complying with Section C405.2.5.2.
2. Spaces with a total of more than 150 watts
			 of
general lighting
within the combined
primary
and
secondary daylight zones
complying with Section C405.2.5.2.
3. Spaces with a total of more than 75 watts
			 of
general lighting
within
toplit daylight
			 zones
complying with Section C405.2.5.3.
EXCEPTION:
Daylight responsive controls
are not
						  required for the following:
1. Spaces in health care facilities where patient care
						  is directly provided.
2. Sidelit daylight zones on the first floor above
						  grade in Group A-2 and Group M occupancies where the fenestration adjoins a
						  sidewalk
C405.2.5.1
Daylight responsive controls
			 function.
Where required, daylight responsive controls shall be provided
			 within each space for control of lights in that space and shall comply with all
			 of the following:
1. Lights in primary sidelit
			 daylight zones shall be controlled independently of lights in secondary sidelit
			 daylight zones in accordance with Section C405.2.5.2.
2. Lights in toplit daylight zones in
			 accordance with Section C405.2.5.3 shall be controlled independently of lights
			 in sidelit daylight zones in accordance with Section C405.2.5.2.
3.
Daylight responsive
			 controls
within each space shall be configured so that they can be
			 calibrated from within that space by authorized personnel.
4. Calibration mechanisms shall be in a
			 location with
ready access
.
5.
Daylight responsive
			 controls
shall dim lights continuously from full light output to 15
			 percent of full light output or lower.
6.
Daylight responsive
			 controls
shall be configured to completely shut off all controlled
			 lights in that zone.
7. When
			 occupant sensor controls have reduced the lighting power to an unoccupied
			 setpoint in accordance with Sections C405.2.1.2 through C405.2.1.4,
daylight responsive controls
shall continue to adjust electric
			 light levels in response to available daylight but shall be configured to not
			 increase the lighting power above the specified unoccupied setpoint.
8. Lights in sidelit daylight zones in
			 accordance with Section C405.2.5.2 facing different cardinal orientations
			 (i.e., within 45 degrees of due north, east, south, west) shall be controlled
			 independently of each other.
EXCEPTION:
Up to 75 watts of
general lighting
are
						  permitted to be controlled together with lighting in a daylight zone facing a
						  different cardinal orientation.
9.
			 Incorporate time-delay circuits to prevent cycling of light level changes of
			 less than three minutes.
10. The
			 maximum area a single
daylight responsive control
device
			 serves shall not exceed 2,500 square feet (232
			 m2).
11.
			 Occupant override capability of daylight dimming controls is not permitted,
			 other than a reduction of light output from the level established by the
			 daylighting controls.
C405.2.5.2
Sidelit daylight zone.
The sidelit daylight zone is the floor area adjacent to vertical
fenestration
which complies with the following:
1. Where the
fenestration
is
			 located in a wall, the primary side-lit daylight zone shall extend laterally to
			 the nearest full height wall, or up to 1.0 times the height from the floor to
			 the top of the
fenestration
, and longitudinally from the edge
			 of the
fenestration
to the nearest full height wall, or up to
			 0.5 times the height from the floor to the top of the fenestration, whichever
			 is less, as indicated in Figure C405.2.5.2(1).
2. The secondary sidelit daylight zone is
			 directly adjacent to the primary daylight zone and shall extend laterally to
			 2.0 times the height from the floor to the top of the
fenestration
or to the nearest full height wall, whichever is
			 less, and longitudinally from the edge of the
fenestration
to
			 the nearest full height wall or up to 2 feet, whichever is less, as indicated
			 in Figure C405.2.5.2(1).
3. Where
clerestory fenestration
is located in a wall, the side-lit
			 daylight zone includes a lateral area twice the depth of the
clerestory
			 fenestration
height, projected upon the floor at a 45 degree angle
			 from the center of the
clerestory fenestration
. The
			 longitudinal width of the sidelit daylight zone is calculated the same as for
fen-estration
located in a wall. Where the 45 degree angle is
			 interrupted by an obstruction greater than 0.7 times the ceiling height, the
			 side-lit daylight zone shall remain the same lateral area but be located
			 between the clerestory and the obstruction, as indicated in Figure
			 C405.2.5.2(2).
4. Where the
fenestration
is located in a rooftop monitor, the sidelit
			 daylight zone shall extend laterally to the nearest obstruction that is taller
			 than 0.7 times the ceiling height, or up to 1.0 times the height from the floor
			 to the bottom of the
fenestration
, whichever is less, and
			 longitudinally from the edge of the
fenestra-tion
to the
			 nearest obstruction that is taller than 0.7 times the ceiling height, or up to
			 0.25 times the height from the floor to the bottom of the
fenestration
, whichever is less, as indicated in Figures
			 C405.2.5.2(3) and C405.2.5.2(4).
5.
			 If the rough opening area of a vertical fenestration assembly is less than 10
			 percent of the calculated primary sidelit daylight zone area for this
			 fenestration, it does not qualify as a sidelit daylight zone.
6. The visible transmittance of the
			 fenestration is no less than 0.20.
7. The projection factor (determined in
			 accordance with Equation 4-5) for any overhanging projection which is shading
			 the
fenestration
is not greater than 1.0 for fenestration
			 oriented 45 degrees or less from true north, and not greater than 1.5 for all
			 other orientations.
Figure C405.2.5.2(1) Sidelit Daylight Zone Adjacent to
				Fenestration in a Wall
Click to view
				image
Figure C405.2.5.2(2) Sidelit Daylight Zone Adjacent to
				Clerestory Fenestration in a Wall
Click to view
				image
Figure C405.2.5.2(3) Sidelit Daylight Zone Under a Sloped
				Rooftop Monitor
Click to view
				image
C405.2.5.3
Toplit daylight zone.
The toplit daylight zone is the floor area underneath a roof fenestration
			 assembly which complies with the following:
1. The toplit daylight zone shall extend
			 laterally and longitudinally beyond the edge of the roof
fenestration
assembly to the nearest obstruction that is
			 taller than 0.7 times the ceiling height, or up to 0.7 times the ceiling
			 height, whichever is less, as indicated in Figure C405.2.5.3(1).
2. Where toplit daylight zones overlap with
			 sidelit daylight zones, lights within the overlapping area shall be assigned to
			 the toplit daylight zone.
3. The
			 product of the
visible transmittance
of the roof
fenestra-tion
assembly and the area of the rough opening of
			 the roof fenestra-tion assembly, divided by the area of the toplit daylight
			 zone is no less than 0.008.
4.
			 Where located under atrium fenestration, the toplit daylight zone shall include
			 the bottom floor area directly beneath the atrium fenestration, and the top
			 floor directly under the atrium fenestration, as indicated in Figure
			 C405.2.5.3(4). The toplit daylight zone area at the top floor is calculated the
			 same as for a toplit daylight zone. Intermediate levels below the top floor
			 that are not directly beneath the atrium are not included.
Figure C405.2.5.3(1) Toplit Daylight Zone Under a Rooftop
				Fenestration Assembly
Click to view
				image
Figure C405.2.5.3(2) Toplit Daylight Zone Under a Rooftop
				Monitor
Click to view
				image
Figure C405.2.5.4 Toplit Daylight Zone Under Atrium
				Fenestration
Click to view
				image
C405.2.5.4
Atriums.
Daylight
			 zones at atrium spaces shall be established at the top floor surrounding the
			 atrium and at the floor of the atrium space, and not on intermediate floors, as
			 indicated in Figure C405.2.5.4.