Title 24 · California Energy Code

Daylit zones: defining primary/secondary sidelit and skylit daylit areas

The Energy Code defines three daylit zones — **primary sidelit**, **secondary sidelit**, and **skylit** — using head‑height and ceiling‑height multipliers (1× and 2× head height for sidelit depths; 0.7× ceiling height for skylights). You must draw those zones on the plans, install daylight‑responsive controls when the lighting wattage in a zone meets the code thresholds (typically 75 W), and only claim daylight PAFs if the controls and zone definitions meet the requirements in **§ 140.3(d)** and **§ 140.6(a)2L**.

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Last reviewed: July 6, 2026

What the code requires — 2-4 sentences

The California Energy Code requires that daylit zones be defined on plans and that lighting in those zones be controlled as daylight zones when thresholds are met. The geometric definitions of primary sidelit daylit zone, secondary sidelit daylit zone, and skylit daylit zone (how far they extend from glazing or skylights) are specified in the code definitions and are the basis for daylight-responsive controls and Power Adjustment Factors (PAFs) in § 140.3(c), § 140.3(d) and for the PAFs referencing those definitions in § 140.6(a)2L. See the code text for the measuring rules and control thresholds cited below.

The single most important rule: define the daylit zones on the drawings exactly using the code’s head‑height and ceiling‑height rules, then apply daylight-responsive controls and any PAFs only to the luminaires that physically fall within those zones.

Requirements in detail

Key definitions (bold on first use)

Primary sidelit daylit zone — the plan area directly adjacent to vertical glazing extending one window head height deep and window width + 0.5 × window head height on each side (minus areas beyond permanent obstructions). This definition is in the code definitions section. § 140.3(c) / definition text.
Secondary sidelit daylit zone — the plan area directly adjacent to the primary sidelit area extending two window head heights deep and using the same sidelit width rules (again minus area beyond permanent obstructions). § 140.3(c) / definition text.
Skylit daylit zone — the rough opening plan area of each skylight plus 0.7 × average ceiling height in each horizontal direction from the skylight edge; the plan shape matches the rough opening (rectangular skylight → rectangular zone). § 140.3(c) / definition text.

Decision‑relevant dimensions and thresholds

Item	Value / rule	Code Reference
Primary sidelit depth	1 × window head height	§ 140.3(c) — definition text.
Secondary sidelit depth	2 × window head height	§ 140.3(c) — definition text.
Sidelit width (each side)	0.5 × window head height added on each side of window width	§ 140.3(c) — definition text.
Skylit horizontal extension	0.7 × average ceiling height in each direction from the skylight rough opening	§ 140.3(c) — skylit daylit zone.
Skylit zone shape	Same geometric plan shape as the rough opening (no rounding)	§ 140.3(c) — skylit daylit zone.
Daylight‑control wattage trigger	Daylight responsive controls required when ≥ 75 watts of general lighting is partially/fully within a daylit zone (primary, secondary or skylit as applicable)	§ 140.3(d) (daylight responsive controls requirements are cross‑referenced in 140.3(d)).
PAF applicability (Table 140.6-A)	PAFs for daylight continuous dimming apply to luminaires in skylit, primary sidelit, and secondary sidelit daylit zones when controls meet the design criteria in § 140.3(d) and § 140.6(a)2L.

(Each of the geometric rules above comes from the code definition paragraphs; use those exact measurements when laying out zones on plans.)

What the PAF clause requires (how § 140.6(a)2L ties in)

The PAF table in § 140.6(a)2L explicitly limits daylight PAFs to luminaires located in primary or secondary sidelit or skylit daylit zones and requires that the daylighting design meet the requirements in § 140.3(d) (e.g., continuous dimming controls per § 130.1(d) when required). Apply PAFs only where those zone definitions and control requirements are met.

Exceptions & special cases

Certain occupancies and project conditions are excepted from the daylighting prescriptions in § 140.3(c) (examples: auditoriums, churches, movie theaters, museums, refrigerated warehouses). Check the full exception list in the code. § 140.3(c).
Unfinished interiors with future enclosed spaces below 5,000 ft² or with ceiling heights ≤ 15 ft may qualify for an exception in § 140.3(c) — this is limited and excludes some occupancy groups (see code).
If permanent architectural features or existing structures block direct beam sun on at least half the roof over the enclosed space for more than 1,500 daytime hours per year (8:00–16:00), some daylight requirements may be waived. § 140.3(c) exceptions.
The PAF rules in § 140.3(d) and the PAF table in § 140.6(a)2L include their own exceptions and qualification conditions (for example, skylit areas smaller than certain sizes or where effective aperture is very low may be exempt from some automatic-control requirements). Always check the exact exception language when claiming a PAF.

Note: the California Green Building Standards Appendix provides alternate or more detailed daylight area calculations (e.g., different side‑width limits such as 2 ft). That can cause confusion if users consult voluntary appendices instead of the mandatory Part 6 definitions — always follow the Part 6 definitions for Energy Code compliance.

Common mistakes

Mis‑measuring window head height or using floor‑to‑ceiling height instead of the code’s specified head‑height measurement. The sidelit depths are tied to window head height, not the room height.
Forgetting to subtract plan areas beyond permanent obstructions (taller than the code threshold) when drawing zones. The code requires subtracting areas behind permanent obstructions.
Double‑counting overlapping zones (skylit vs sidelit). The code disallows double counting when determining areas for PAFs and for meeting daylighting area percentages. Carefully clip overlap on plans.
Failing to show all skylit and sidelit daylit zones on the construction documents — the code explicitly requires these zones be shown. § 140.3(c) / daylight responsive controls requirements.
Applying PAFs without meeting the control requirements (continuous dimming and OFF behavior) specified in § 140.3(d) and in the PAF rules. PAFs are only allowed when the control performance and installation conditions are satisfied.

Worked example — concrete numbers

Scenario: an interior office room has a vertical window with window head height = 12 ft, window width = 6 ft, and a ceiling height = 10 ft. There is also a rectangular skylight with a rough opening of 4 ft × 6 ft.

Primary sidelit daylit zone (per § 140.3(c)):
- Depth = 1 × head height = 12 ft.
- Width = window width + 0.5 × head height on each side = 6 ft + (0.5×12) + (0.5×12) = 6 + 6 + 6 = 18 ft total.
- Primary area = 18 ft × 12 ft = 216 ft².
Secondary sidelit daylit zone (per § 140.3(c)):
- Depth = 2 × head height = 24 ft. Width same = 18 ft.
- Secondary area = 18 ft × 24 ft = 432 ft². (When reporting totals do not double count the primary area inside that secondary area — code treats them as distinct zones for controls and PAFs).
Skylit daylit zone (per § 140.3(c) and skylight rule):
- Horizontal extension = 0.7 × ceiling height = 0.7 × 10 ft = 7 ft in each direction.
- Plan size = (4 + 2×7) ft by (6 + 2×7) ft = 18 ft × 20 ft = 360 ft².
Controls and PAF considerations:
- If ≥ 75 W of general lighting falls inside any of these daylit zones, daylight responsive controls are required for that zone per § 140.3(d). If you want the daylight continuous‑dimming PAF in § 140.6(a)2L, your controls and zone definitions must meet the requirements in § 140.3(d) (continuous dimming, OFF behavior, etc.).

Related provisions

§ 140.3(c) — daylighting definitions and some mandatory daylight design items (see definitions cited above).
§ 140.3(d) — daylight responsive controls and the daylighting design elements used to qualify for PAFs.
§ 140.6(a)2L — PAF table (Table 140.6‑A) clause L: links PAF eligibility to the daylighting design requirements in § 140.3(d).
§ 130.1(d) — automatic daylighting control performance and exceptions (controls behavior, sensor placement, and OFF thresholds referenced by 140.3(d)).
Appendix/GHRS daylight definitions (voluntary/GBSC) — contains alternate examples and slightly different dimensional guidance (useful for green‑building calculations but not a substitute for Part 6 mandatory definitions).

Code references

Grounded in the retrieved California Energy Code — click a citation to read the verbatim passage:

§ 160.5 High relevance — show source text
No more than 500 watts of rated lighting power shall be controlled together as a single zone; and iii. The occupant sensing controls shall be capable of automatically turning the lighting fully ON only in the separately controlled zone and shall be automatically activated from all designed paths of egress. Interior areas of parking garages are under the classification of indoor lighting and shall comply with Section 160.5(b)4Cvic. Parking areas on the roof of a parking structure are under the classification of outdoor hardscape and shall comply with Section 160.5(c). D. Daylight responsive controls. Daylight responsive controls shall be installed in the following locations, as applicable: i. In any enclosed space where the total installed wattage of general lighting luminaires completely or partially within skylit daylit zones is 75 watts or greater, the general lighting in the skylit daylit zones shall be controlled by daylight responsive controls. ii. In any enclosed space where the total installed wattage of general lighting luminaires completely or partially within primary sidelit daylit zones is 75 watts or greater, the general lighting in the primary sidelit daylit zones shall be controlled by daylight responsive controls. iii. In any enclosed space where the total wattage of general lighting luminaires in the secondary zones is 75 watts or greater, the general lighting in the secondary sidelit daylit zones shall be controlled by daylight responsive controls. General lighting in the secondary sidelit daylit zones shall be controlled independently of general lighting in the primary sidelit daylit zones. iv. For skylights located in an atrium, the skylit daylit zones shall apply to the floor area directly under the atrium and the top floor area directly adjacent to the atrium. v. Parking garage areas where the total installed wattage of the general lighting in the primary and the secondary sidelit daylit zones is 60 watts or greater, the general lighting in the primary and secondary sidelit daylit zones shall be controlled by daylight responsive controls. All daylight responsive controls shall meet the following requirements: vi. All skylit daylit zones, primary sidelit daylit zones, secondary sidelit daylit zones and the combined primary and secondary sidelit daylit zones in parking garages shall be shown on the plans; and NOTE: Parking areas on the roof of a parking structure are outdoor hardscape, not skylit daylit areas. vii. The daylight responsive controls shall provide separate control for general lighting in each type of daylit zone. The daylight responsive controls shall meet the following: a. General lighting in overlapping skylit daylit zone and sidelit daylit zone shall be controlled as part of the skylit daylit zone.

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MULTIFAMILY BUILDINGS—MANDATORY REQUIREMENTS

b. General lighting in overlapping primary and secondary sidelit daylit zone shall be controlled as part of the primary sidelit daylit zone. c. General lighting luminaires longer than 8 feet shall be controlled as segments of 8 feet or less according to the type of the daylit zone where the segment is primarily located; and Exception to Section 160.5(b)4Dviic: Where a luminaire contains a factory-assembled housing and light source as an integral unit in segments longer than 8 feet, the luminaire is allowed to be controlled according to the type of the daylit zone in which the segment is primarily located. viii. The daylight responsive controls shall meet the following: a.
§ 130.1 High relevance — show source text
General lighting in the secondary sidelit daylit zones shall be controlled independently of general lighting in the primary sidelit daylit zones.

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NONRESIDENTIAL AND HOTEL/MOTEL OCCUPANCIES—MANDATORY REQUIREMENTS FOR LIGHTING SYSTEMS AND EQUIPMENT, AND ELECTRICAL POWER DISTRIBUTION SYSTEMS

D. For skylights located in an atrium, the skylit daylit zone definition shall apply to the floor area directly under the atrium and the top floor area directly adjacent to the atrium. E. Parking garage areas where the total installed wattage of the general lighting in the primary and the secondary sidelit daylit zones is 60 watts or greater, the general lighting in the primary and secondary sidelit daylit zones shall be controlled by daylight responsive controls. 2. All daylight responsive controls shall meet the following requirements: A. All skylit daylit zones, primary sidelit daylit zones, secondary sidelit daylit zones, and the combined primary and secondary sidelit daylit zones in parking garages shall be shown on the plans; and Note: Parking areas on the roof of a parking structure are outdoor hardscape, not skylit daylit areas. B. The daylight responsive controls shall provide separate control for general lighting in each type of daylit zone. The daylight responsive controls shall meet the following: i. General lighting in overlapping skylit daylit zone and sidelit daylit zone shall be controlled as part of the skylit daylit zone. ii. General lighting in overlapping primary and secondary sidelit daylit zones shall be controlled as part of the primary sidelit daylit zone. iii. General lighting luminaires longer than 8 feet shall be controlled as segments of 8 feet or less according to the type of the daylit zone in which the segment is primarily located; and Exception to Section 130.1(d)2Biii: Where a luminaire contains a factory assembled housing and light source as an integral unit in segments longer than 8 feet, the luminaire segment is allowed to be controlled according to the type of the daylit zone in which the segment is primarily located. C. The daylight responsive controls shall meet the following: i. For spaces where the installation of multilevel lighting controls is required under Section 130.1(b), allow the multilevel lighting controls to adjust the light level with continuous dimming; ii. For each space, ensure the combined illuminance from the controlled lighting and daylight is not less than the illuminance from controlled lighting when no daylight is available; iii. For areas other than parking garages, ensure that, when the daylight illuminance is greater than 150 percent of the illuminance provided by the controlled lighting when no daylight is available, the controlled lighting power in that daylight zone shall be reduced by a minimum of 90 percent; and iv. For parking garages, ensure that when daylight illuminance levels measured at the farthest edge of the secondary sidelit zone away from the glazing or opening are greater than 150 percent of the illuminance provided by the controlled lighting when no daylight is available, the controlled lighting power in the combined primary and secondary sidelit daylit zones shall be reduced by 100 percent; and D. Photosensors shall be located so that they are not readily accessible to unauthorized personnel; and E. The location where calibration adjustments are made to the daylight responsive controls shall be readily accessible to authorized personnel but may be inside a locked case or under a cover which requires a tool for access; and F.
§ 209.2.3.1.4 High relevance — show source text
The secondary sidelit depth is the horizontal distance perpendicular to the glazing which begins from one window head height and ends at the smaller of:
1. Two window head heights;
2. The distance to any 5 feet or higher permanent vertical obstruction; or
3. The distance to any skylit daylight area.
A6.209.2.3.1.4 Daylight area, skylit is the combined daylight area under each skylight without double counting overlapping areas. The daylight area under each skylight is bounded by the rough opening of the skylight, plus horizontally in each direction the smallest of:
1. 70 percent of the floor-to-ceiling height; or
2. The distance to any primary sidelit area or the daylight area under rooftop monitors; or
3. The distance to any permanent partition or permanent rack which is farther away than 70 percent of the distance between the top of the permanent partition or permanent rack and the ceiling.
A6.209.2.3.2 Luminaires providing general lighting that are in or are partially in the skylit daylight area and/or the primary sidelit daylight area shall be controlled as follows:

A6.209.2.3.2.1 Primary sidelit and skylit daylight areas shall have at least one lighting control that:
1. Controls at least 50 percent of the general lighting power in the primary sidelit and skylit daylight areas separately from other lighting in the enclosed space.
2. Controls luminaires in primary sidelit areas separately from skylit areas.
Exception: Primary sidelit and skylit daylight areas that have a combined area totaling less than or equal to 250 square feet within any enclosed space.

A6.209.2.3.2.2 For all skylit daylight areas:
1. The skylit daylight area shall be shown on the plans.
2. All of the general lighting in the skylit area shall be controlled independently by an automatic daylighting control device that meets the applicable requirements of Section A6.209.1.
2025 CALIFORNIA GREEN BUILDING STANDARDS CODE APPENDIX A6.1-25

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APPENDIX A6.1 — VOLUNTARY STANDARDS FOR HEALTH FACILITIES [OSHPD 1, 2 & 4]
1. The automatic daylighting control shall be installed in accordance with Section A6.209.2.3.2.4.
Exceptions:
1. Where the total skylit daylight area in any enclosed space is less than or equal to 2,500 square feet.
2. Skylit daylight areas where existing adjacent structures obstruct direct beam sunlight for at least 6 hours per day during the equinox as calculated using computer or graphical methods.
3. When the skylight effective aperture is greater than 4.0 percent and all general lighting in the skylit area is controlled by a multilevel astronomical time switch that meets the requirements of Section A6.209.1.8 and that has an override switch that meets the requirements of Section A6.209.2.4.2.
4. Skylit daylight areas where the effective aperture is less than 0.006. The effective aperture for skylit daylight areas is specified in Section 146(a)2E of Title 24, Part 6.
§ 209.2.3 High relevance — show source text
Exceptions:
1. Lights in corridors.
2. A space that has only one luminaire with no more than two lamps.
A6.209.2.3 Daylight areas.

A6.209.2.3.1 Daylight areas shall be defined as follows:

A6.209.2.3.1.1 Daylight area. The total daylight area shall not double count overlapping areas with any primary sidelit daylight area, secondary sidelit daylight area or skylit daylight area.

A6.209.2.3.1.2 Daylight area, primary sidelit is the combined primary sidelit area without double counting overlapping areas. The floor area for each primary sidelit area is directly adjacent to vertical glazing below the ceiling with an area equal to the product of the sidelit width and the primary sidelit depth.

The primary sidelit width is the width of the window plus, on each side, the smallest of:
1. 2 feet; or
2. The distance to any 5 feet or higher permanent vertical obstruction.
The primary sidelit depth is the horizontal distance perpendicular to the glazing which is the smaller of:
1. One window head height; or
2. The distance to any 5 feet or higher permanent vertical obstruction.
A6.209.2.3.1.3 Daylight area, secondary sidelit is the combined secondary sidelit area without double counting overlapping areas. The floor area for each secondary sidelit area is directly adjacent to primary sidelit area with an area equal to the product of the sidelit width and the secondary sidelit depth.

The secondary sidelit width is the width of the window plus, on each side, the smallest of:
1. 2 feet; or
2. The distance to any 5 feet or higher permanent vertical obstruction; or
3. The distance to any skylit daylight area.
The secondary sidelit depth is the horizontal distance perpendicular to the glazing which begins from one window head height and ends at the smaller of:
1. Two window head heights;
2. The distance to any 5 feet or higher permanent vertical obstruction; or
3. The distance to any skylit daylight area.
A6.209.2.3.1.4 Daylight area, skylit is the combined daylight area under each skylight without double counting overlapping areas. The daylight area under each skylight is bounded by the rough opening of the skylight, plus horizontally in each direction the smallest of:
1. 70 percent of the floor-to-ceiling height; or
2. The distance to any primary sidelit area or the daylight area under rooftop monitors; or
3. The distance to any permanent partition or permanent rack which is farther away than 70 percent of the distance between the top of the permanent partition or permanent rack and the ceiling.
A6.209.2.3.2 Luminaires providing general lighting that are in or are partially in the skylit daylight area and/or the primary sidelit daylight area shall be controlled as follows:

A6.209.2.3.2.1 Primary sidelit and skylit daylight areas shall have at least one lighting control that:
1. Controls at least 50 percent of the general lighting power in the primary sidelit and skylit daylight areas separately from other lighting in the enclosed space.
2. Controls luminaires in primary sidelit areas separately from skylit areas.
Exception: Primary sidelit and skylit daylight areas that have a combined area totaling less than or equal to 250 square feet within any enclosed space.
§ 160.5 High relevance — show source text
All daylight responsive controls shall meet the following requirements: vi. All skylit daylit zones, primary sidelit daylit zones, secondary sidelit daylit zones and the combined primary and secondary sidelit daylit zones in parking garages shall be shown on the plans; and NOTE: Parking areas on the roof of a parking structure are outdoor hardscape, not skylit daylit areas. vii. The daylight responsive controls shall provide separate control for general lighting in each type of daylit zone. The daylight responsive controls shall meet the following: a. General lighting in overlapping skylit daylit zone and sidelit daylit zone shall be controlled as part of the skylit daylit zone.

2025 CALIFORNIA ENERGY CODE 229

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MULTIFAMILY BUILDINGS—MANDATORY REQUIREMENTS

b. General lighting in overlapping primary and secondary sidelit daylit zone shall be controlled as part of the primary sidelit daylit zone. c. General lighting luminaires longer than 8 feet shall be controlled as segments of 8 feet or less according to the type of the daylit zone where the segment is primarily located; and Exception to Section 160.5(b)4Dviic: Where a luminaire contains a factory-assembled housing and light source as an integral unit in segments longer than 8 feet, the luminaire is allowed to be controlled according to the type of the daylit zone in which the segment is primarily located. viii. The daylight responsive controls shall meet the following: a. For spaces where the installation of multilevel lighting controls is required under Section 160.5(b)4B, allow the multilevel lighting controls to adjust the light level with continuous dimming; b. For each space, ensure the combined illuminance from the controlled lighting and daylight is not less than the illuminance from controlled lighting when no daylight is available; c. For areas other than parking garages, ensure that when the daylight illuminance is greater than 150 percent of the illuminance provided by the controlled lighting system when no daylight is available, the controlled lighting power in that daylight zone shall be reduced by a minimum of 90 percent; and d. For parking garages, ensure that when daylight illuminance levels measured at the farthest edge of the secondary sidelit zone away from the glazing or opening are greater than 150 percent of the illuminance provided by the controlled lighting when no daylight is available, the controlled lighting power in the combined primary and secondary sidelit daylight zones shall be reduced by 100 percent; and ix. Photosensors shall be located so that they are not readily accessible to unauthorized personnel; and x. The location where calibration adjustments are made to the daylight responsive controls shall be readily accessible to authorized personnel but may be inside a locked case or under a cover that requires a tool for access; and xi. Interaction with other lighting controls in a space where manual controls are required, the manual controls shall be capable of turning off or decreasing light levels below the light level set by the daylight responsive controls. Exception 1 to Section 160.5(b)4D: Areas under skylights where it is documented that existing adjacent structures or natural objects block direct sunlight for more than 1,500 daytime hours per year between 8 a.m. and 4
§ 160.5 High relevance — show source text
The occupant sensing controls shall be capable of automatically turning the lighting fully ON only in the separately controlled space, and shall be automatically activated from all designed paths of egress. b. In office spaces greater than 250 square feet, general lighting shall be controlled by occupancy sensing controls that meet all of the following: I. The occupancy sensing controls shall be configured so that lighting shall be controlled separately in control zones not greater than 600 square feet. All control zones in offices greater than 250 square feet shall be shown on the plans; and II. In 20 minutes or less after the control zone is unoccupied, the occupancy sensing controls shall uniformly reduce lighting power in the control zone to no more than 20 percent of full power. Control functions that switch control zone lights completely off when the zone is vacant meet this requirement; and III. In 20 minutes or less after the entire office space is unoccupied, the occupancy sensing controls shall automatically turn off lighting in all control zones in the space; and IV. In each control zone, lighting shall be allowed to automatically turn on to any level up to full power upon occupancy within the control zone. When occupancy is detected in any control zone in the space, the lighting in other control zones that are unoccupied shall operate at no more than 20 percent of full power. Exception to Section 160.5(b)4Cvib: Under-shelf or furniture-mounted task lighting controlled by a local switch and either a time switch or an occupancy sensor. c. In parking garages, parking areas, and loading and unloading areas, general lighting shall be controlled by occupant sensing controls that meet the requirements below instead of complying with Section 160.5(b)4Ci: i. The occupant sensing controls shall uniformly reduce lighting power in the control zone to between 20 percent and 50 percent of full power and with at least one control step; and ii. No more than 500 watts of rated lighting power shall be controlled together as a single zone; and iii. The occupant sensing controls shall be capable of automatically turning the lighting fully ON only in the separately controlled zone and shall be automatically activated from all designed paths of egress. Interior areas of parking garages are under the classification of indoor lighting and shall comply with Section 160.5(b)4Cvic. Parking areas on the roof of a parking structure are under the classification of outdoor hardscape and shall comply with Section 160.5(c). D. Daylight responsive controls. Daylight responsive controls shall be installed in the following locations, as applicable: i. In any enclosed space where the total installed wattage of general lighting luminaires completely or partially within skylit daylit zones is 75 watts or greater, the general lighting in the skylit daylit zones shall be controlled by daylight responsive controls. ii. In any enclosed space where the total installed wattage of general lighting luminaires completely or partially within primary sidelit daylit zones is 75 watts or greater, the general lighting in the primary sidelit daylit zones shall be controlled by daylight responsive controls. iii. In any enclosed space where the total wattage of general lighting luminaires in the secondary zones is 75 watts or greater, the general lighting in the secondary sidelit daylit zones shall be controlled by daylight responsive controls. General lighting in the secondary sidelit daylit zones shall be controlled independently of general lighting in the primary sidelit daylit zones. iv. For skylights located in an atrium, the skylit daylit zones shall apply to the floor area directly under the atrium and the top floor area directly adjacent to the atrium.

§ 130.4 High relevance — show source text

The setting of the limit is verified by the acceptance test required by Section 130.4(a)7; and iv. The construction documents specify which lighting systems shall have their maximum light output or maximum power draw set to no greater than 85 percent of full light output or full power draw. K. To qualify for the PAF for a demand responsive control in Table 140.6-A, the general lighting wattage receiving the PAF shall not be within the scope of Section 110.12(c) and a demand responsive control shall meet all of the following requirements: i. The controlled lighting shall be capable of being automatically reduced in response to a demand response signal; and ii. General lighting shall be reduced in a manner consistent with the requirements of Section 130.1(b). L. To qualify for the PAFs for clerestory fenestration, horizontal slats, or light shelves in Table 140.6-A, the daylighting design shall meet the requirements in Section 140.3(d). The PAFs shall only apply to lighting in a primary or secondary sidelit daylit zone where continuous dimming daylighting controls meeting the requirements of Section 130.1(d) are installed.

TABLE 140.6-A—LIGHTING POWER ADJUSTMENT FACTORS (PAF)	Col2	Col3
TYPE OF CONTROL	TYPE OF AREA	FACTOR
1. Daylight continuous dimming plus OFF control	Luminaires in skylit daylit zone or primary sidelit daylit zone or secondary sidelit daylit zone	0.10
2. Occupant sensing controls in offices larger than 250 square feet	One sensor controlling an area that is no larger than 125 square feet	0.30
3. Occupant sensing controls in offices larger than 250 square feet	One sensor controlling an area that is 126-250 square feet	0.20
4. Institutional tuning	Luminaires in non-daylit areas: Luminaires that qualify for other PAFs in this table may also qualify for this tuning PAF.	0.10
4. Institutional tuning	Luminaires in daylit areas: Luminaires that qualify for other PAFs in this table may also qualify for this tuning PAF.	0.05
5. Demand responsive control	General lighting luminaires not in the scope of Section 110.12(c). If DR controls are required of Section 110.12(c), this PAF is not available for any lighting in the project. Luminaires that qualify for other PAFs in this table may also qualify for this demand responsive control PAF.	0.05
6. Clerestory fenestration	Luminaires in daylit areas adjacent to the clerestory. Luminaires that qualify for daylight dimming plus OFF control may also qualify for this PAF.	0.05
7. Horizontal slats	Luminaires in daylit areas adjacent to vertical fenestration with interior or exterior horizontal slats. Luminaires that qualify for daylight dimming plus OFF control may also qualify for this PAF.	0.05
8. Light shelves	Luminaires in daylit areas adjacent to clerestory fenestration with interior or exterior light shelves. This PAF may be combined with the PAF for clerestory fenestration. Luminaires that qualify for daylight dimming plus OFF control may also qualify for this PAF.	0.10
a.

§ 130.1 High relevance — show source text
1. All skylit daylit zones and primary sidelit daylit zones shall be shown on building plans.
2. General lighting in daylit zones shall be controlled in accordance with Section 130.1(d).
3. The total skylight area is at least 3 percent of the total floor area in the space within a horizontal distance of 0.7 times the average ceiling height from the edge of rough opening of skylights; or the product of the total skylight area and the average skylight visible transmittance is no less than 1.5 percent of the total floor area in the space within a horizontal distance of 0.7 times the average ceiling height from the edge of rough opening of skylights.
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NONRESIDENTIAL AND HOTEL/MOTEL OCCUPANCIES—PERFORMANCE AND PRESCRIPTIVE

COMPLIANCE APPROACHES FOR ACHIEVING ENERGY EFFICIENCY
1. All skylights shall have a glazing material or diffuser that has a measured haze value greater than 90 percent, tested according to ASTM D1003 (notwithstanding its scope) or other test method approved by the Commission.
2. Skylights for conditioned and unconditioned spaces shall have an area-weighted average visible transmittance (VT) no less than the applicable value required by Section 140.3(a)6D.
Exception 1 to Section 140.3(c): Auditoriums, churches, movie theaters, museums and refrigerated warehouses.

Exception 2 to Section 140.3(c): In buildings with unfinished interiors, future enclosed spaces for which there are plans to have: A. A floor area of less than or equal to 5,000 square feet, or B. Ceiling heights of less than or equal to 15 feet.

This exception shall not be used for S-1 or S-2 (storage), or for F-1 or F-2 (factory) occupancies.

Exception 3 to Section 140.3(c): Enclosed spaces having a designed general lighting system with a lighting power density less than 0.5 watts per square foot.

Exception 4 to Section 140.3(c): Enclosed spaces where it is documented that permanent architectural features of the building, existing structures or natural objects block direct beam sunlight on at least half of the roof over the enclosed space for more than 1500 daytime hours per year between 8 a.m. and 4 p.m.

(d) Daylighting Design Power Adjustment Factors (PAFs). To qualify for a Power Adjustment Factor (PAF) as specified in Section 140.6(a)2L, daylighting devices shall meet the following requirements:
1. Clerestory fenestration. To qualify for a PAF, clerestory fenestration shall meet the following requirements: A. Shall be installed on east-, west-, or south-facing facades. B. Shall have a head height that is at least 10 feet above the finished floor. C. Shall have a glazing height that is greater than or equal to 10 percent of the head height. D. If operable shading is installed on the clerestory fenestration, then the clerestory fenestration shading shall be controlled separately from shading serving other vertical fenestration.
2. **Interior and exterior horizontal slats.
§ 160.5 High relevance — show source text
2025 CALIFORNIA ENERGY CODE 243

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

MULTIFAMILY BUILDINGS—PERFORMANCE AND PRESCRIPTIVE COMPLIANCE APPROACHES

(b) Minimum daylighting requirement for large enclosed spaces. In Climate Zones 2 through 15, conditioned enclosed spaces and unconditioned enclosed spaces that are greater than 5,000 ft2 and that are directly under a roof with ceiling heights greater than 15 feet shall meet the following requirements:
1. A combined total of at least 75 percent of the floor area, as determined in building floor plan (drawings) view, shall be within one or more of the following: A. Primary sidelight daylight zone in accordance with Section 160.5(b)4Dib, or B. The total floor area in the space within a horizontal distance of 0.7 times the average ceiling height from the edge of rough opening of skylights.
2. All skylit daylit zones and primary sidelit daylit zones shall be shown on building plans.
3. General lighting in daylit zones shall be controlled in accordance with Section 160.5(b)4D.
4. The total skylight area is at least 3 percent of the total floor area in the space within a horizontal distance of 0.7 times the average ceiling height from the edge of rough opening of skylights; or the product of the total skylight area and the average skylight visible transmittance is no less than 1.5 percent of the total floor area in the space within a horizontal distance of 0.7 times the average ceiling height from the edge of rough opening of skylights.
5. All skylights shall have a glazing material or diffuser that has a measured haze value greater than 90 percent, tested according to ASTM D1003 (notwithstanding its scope) or another test method approved by the Commission. Exception 1 to Section 170.2(b): In buildings with unfinished interiors, future enclosed spaces for which there are plans to have:
A. A floor area of less than or equal to 5,000 square feet; or B. Ceiling heights of less than or equal to 15 feet. This exception shall not be used for S-1 or S-2 (storage), or for F-1 or F2 (factory) occupancies. Exception 2 to Section 170.2(b): Enclosed spaces having a designed general lighting system with a lighting power density less than 0.5 watts per square foot. Exception 3 to Section 170.2(b): Enclosed spaces where it is documented that permanent architectural features of the building, existing structures or natural objects block direct beam sunlight on at least half of the roof over the enclosed space for more than 1500 daytime hours per year between 8 a.m. and 4 p.m.

(c) Space-conditioning systems. All space heating, space cooling and ventilation equipment shall comply with minimum Appliance Efficiency Regulations as specified in Sections 110.0 through 110.2 and the applicable requirements of Subsections 1 through 4.
1. Sizing and equipment selection—common use areas. Mechanical heating and mechanical cooling equipment serving common use areas of multifamily buildings shall be the smallest size, within the available options of the desired equipment line, necessary to meet the design heating and cooling loads of the building, as calculated according to Subsection 2 below.
§ 0.7 Medium relevance — show source text
A building of Occupancy Group U when located on a residential site.

SINGLE PACKAGE VERTICAL AIR CONDITIONER (SPVAC) is a type of air-cooled small or large commercial package air-conditioning and heating equipment; factory assembled as a single package having its major components arranged vertically, which is an encased combination of cooling and optional heating components; is intended for exterior mounting on, adjacent interior to, or through an outside wall; and is powered by single or three-phase current. It may contain separate indoor grille, outdoor louvers, various ventilation options, indoor free air discharge, ductwork, wall plenum or sleeve. Heating components may include electrical resistance, steam, hot water, gas, or no heat but may not include reverse cycle refrigeration as a heating means.

SINGLE PACKAGE VERTICAL HEAT PUMP (SPVHP) is an SPVAC that utilizes reverse cycle refrigeration as its primary heat source, with secondary supplemental heating by means of electrical resistance, steam, hot water or gas.

SINGLE ZONE CONSTANT VOLUME HEAT PUMP (SZHP) is an air-source heat pump that uses a supply fan with a speed that does not

vary.

SINGLE ZONE SYSTEM is an air distribution system that supplies air to one thermal zone controlled by a single thermostat.

SITE SOLAR ENERGY is thermal, chemical or electrical energy derived from direct conversion of incident solar radiation at the building site.

SKYLIGHT is fenestration installed on a roof less than 60 degrees from the horizontal.

SKYLIGHT AREA is the area of the rough opening for the skylight.

SKYLIGHT TYPE is one of the following three types of skylights: glass mounted on a curb, glass not mounted on a curb, or plastic (assumed to be mounted on a curb).

SKYLIT DAYLIT ZONE is the rough area in plan view under each skylight, plus 0.7 times the average ceiling height in each direction from the edge of the rough opening of the skylight, minus any area on a plan beyond a permanent obstruction that is taller than onehalf of the distance from the floor to the bottom of the skylight. The bottom of the skylight is measured from the bottom of the skylight well for skylights having wells, or the bottom of the skylight if no skylight well exists. For the purpose of determining the skylit daylit zone, the geometric shape of the skylit daylit zone shall be identical to the plan view geometric shape of the rough opening of the skylight; for example, for a rectangular skylight the skylit daylit zone plan area shall be rectangular, and for a circular skylight the skylit daylit zone plan area shall be circular. For skylight located in an atrium, the skylit daylit zone shall include the floor area directly under the atrium, and the area of the top floor that is directly under the skylight, plus 0.7 times the average ceiling height of the top floor, in each direction from the edge of the rough opening of the skylight, minus any area on a plan beyond a permanent obstruction that is taller than one-half of the distance from the top floor to the bottom of the skylight.

SMACNA is the Sheet Metal and Air-conditioning Contractors National Association.

§ 170.2 Medium relevance — show source text

xi. To qualify for the PAF for a demand responsive control in Table 170.2-L, the general lighting wattage receiving the PAF shall not be within the scope of Section 110.12(c) and a demand responsive control shall meet all of the following requirements: a. The controlled lighting shall be capable of being automatically reduced in response to a demand response signal; and b. General lighting shall be reduced in a manner consistent with the illuminance uniformity requirements of Section 160.5(b)4B. xii. To qualify for the PAFs for clerestory fenestration, horizontal slats or light shelves in Table 170.2-L, the daylighting design shall meet the requirements in Section 170.2(b). The PAFs shall only apply to lighting in a primary or secondary sidelit daylit zone where continuous dimming daylighting controls meeting the requirements of Section 160.5(b)4D are installed.

TABLE 170.2-L—LIGHTING POWER ADJUSTMENT FACTORS (PAF)	Col2	Col3
TYPE OF CONTROL	TYPE OF AREA	FACTOR
1. Daylight Continuous Dimming Plus OFF Control	Luminaires in skylit daylit zone or primary sidelit daylit zone	0.10
2. Occupant Sensing Controls in Office Spaces Larger Than 250 Square Feet	In open plan offices > 250 square feet: One sensor controlling an area that is: No larger than 125 square feet	0.30
2. Occupant Sensing Controls in Office Spaces Larger Than 250 Square Feet	In open plan offices > 250 square feet: One sensor controlling an area that is: From 126 to 250 square feet	0.20
3. Institutional Tuning	Luminaires in nondaylit areas. Luminaires that qualify for other PAFs in this table may also qualify for this tuning PAF.	0.10
3. Institutional Tuning	Luminaires in daylit areas. Luminaires that qualify for other PAFs in this table may also qualify for this tuning PAF.	0.05
4. Demand Responsive Control	General lighting luminaires not in the scope of Section 110.12(c). Luminaires that qualify for other PAFs in this table may also qualify for this demand responsive control PAF.	0.05
5. Clerestory Fenestration	Luminaires in daylit areas adjacent to the clerestory. Luminaires that qualify for daylight dimming plus OFF control may also qualify for this PAF.	0.05
6. Horizontal Slats	Luminaires in daylit areas adjacent to vertical fenestration with interior or exterior horizontal slats. Luminaires that qualify for daylight dimming plus OFF control may also qualify for this PAF.	0.05
7. Light Shelves	Luminaires in daylit areas adjacent to clerestory fenestration with interior or exterior light shelves. This PAF may be combined with the PAF for clerestory fenestration. Luminaires that qualify for daylight dimming plus OFF control may also qualify for this PAF.	0.10
a. To qualify for any of the power adjustment factors in this table, the installation shall comply with the applicable requirements in Section 170.2(e)1Aii. b. Only one PAF may be used for each qualifying luminaire unless combined. c.

Frequently asked questions

How do I measure "window head height" for the sidelit depths?

Measure from the finished floor to the top (head) of the window opening as used in the code definition — sidelit depths are specified as multiples of that head height. § 140.3(c).

Do skylit and sidelit zones overlap — and can I count the overlap twice?

No. Overlapping daylight areas must not be double‑counted when determining daylight area, controls, or PAF eligibility. The code requires combined daylight areas to be computed without double counting.

When is an automatic daylight control required?

Daylight responsive controls are required when the total installed wattage of general lighting within a skylit or primary sidelit daylit zone is 75 W or greater (similar threshold applies to secondary zones) — see § 140.3(d).

Can I apply the PAF in Table 140.6‑A if my daylight controls are simple on/off?

No — the PAFs for daylight continuous‑dimming require controls that meet the specific performance criteria in § 140.3(d) (continuous dimming and OFF behavior as specified). Also, § 140.6(a)2L ties PAF eligibility to those design/control requirements.

What if an overhang completely shades the windows?

There are exceptions where overhangs or obstructions that permanently block direct sun can exempt areas from some daylight control requirements; check the exception language in § 140.3(c) and related control exceptions in § 130.1(d).

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Related in the California Energy Code

PAFs for clerestory fenestration, light shelves and horizontal slats

Daylight-responsive controls: continuous dimming plus OFF, photosensor location and setpoints

Daylighting design, daylight-responsive controls and daylight-related PAFs

California Energy Code