LEED v4 EQ Daylight Credit: sDA Thresholds, ASE Cap, and Points (v4, 2019 addenda)

LEED v4 BD+C EQ Credit Daylight rewards projects that bring daylight into regularly occupied spaces. The credit awards 1-3 points for New Construction through three options (1-2 points for Healthcare). The highest-scoring route is Option 1: Spatial Daylight Autonomy (sDA300/50%) of at least 75% of regularly occupied floor area earns 3 points, and Annual Sunlight Exposure (ASE1000,250) must stay at or below 10%. Source: LEED v4 BD+C rating system, July 2019 addenda, pp. 131-133. This article covers LEED v4 BD+C; LEED v4.1 is not covered. LEED v5 has also been released (USGBC) and is not covered.

Key numbers at a glance

EQ Credit Daylight offers three compliance options with different evidence methods and point scales. All three require manual or automatic (with manual override) glare-control devices for all regularly occupied spaces. Option 1 uses annual simulation of sDA300/50% and ASE1000,250. Option 2 uses illuminance calculations on clear-sky days at the equinox. Option 3 uses measurements in the finished building. The ASE cap applies only to Option 1: if ASE1000,250 exceeds 10%, Option 1 earns nothing even when the sDA target is met.

Healthcare projects use perimeter floor area rather than regularly occupied floor area and a lower point scale (Option 1: sDA 75% = 1 point, 90% = 2; Options 2 and 3: 75% = 1, 90% = 2).

Why were these thresholds established?

The credit’s stated intent is to connect building occupants with the outdoors, reinforce circadian rhythms and reduce the use of electrical lighting by introducing daylight into the space. The two Option 1 metrics balance each other: sDA300/50% counts the share of floor area receiving at least 300 lux for at least 50% of analysis hours, which rewards daylight availability, and ASE1000,250 counts the share of area receiving 1,000 lux or more of direct sun for 250 or more hours a year, which limits glare and overheating from too much glazing. The credit text does not give a research basis for the specific percentages, and none is claimed here.

What are the three compliance options?

Option 1, annual simulation (sDA + ASE): Demonstrate through annual computer simulation that sDA300/50% reaches 55% (2 points) or 75% (3 points) of regularly occupied floor area, and that ASE1000,250 is no more than 10% of the regularly occupied floor area that is daylit per the sDA simulations. Calculation grids must be no more than 2 feet (600 mm) square, at a work plane height of 30 inches (760 mm) above finished floor, using an hourly time-step analysis based on typical meteorological year data. Permanent interior obstructions are included; moveable furniture and partitions may be excluded.

Option 2, illuminance calculations: Model illuminance between 300 lux and 3,000 lux at 9 a.m. and 3 p.m. on a clear-sky day at the equinox. Select one day within 15 days of September 21 and one within 15 days of March 21 that represent the clearest sky, and use the average of the hourly values for the two days. Blinds and shades are excluded from the model. 75% of regularly occupied floor area earns 1 point; 90% earns 2 points.

Option 3, measurement: With furniture, fixtures and equipment in place, measure illuminance between 300 lux and 3,000 lux at the work plane during any hour between 9 a.m. and 3 p.m. Take one measurement in any regularly occupied month and a second in a month set by Table 4 of the credit (for example, a first measurement in January requires a second in May through September). 75% of regularly occupied floor area earns 2 points; 90% earns 3 points. For spaces larger than 150 square feet use a maximum 10 foot grid; for spaces of 150 square feet or smaller, a maximum 3 foot grid.

What triggers ASE disqualification?

Annual Sunlight Exposure (ASE1000,250) is the share of the regularly occupied floor area, daylit per the sDA simulation, that receives 1,000 lux or more for at least 250 hours per year. Because the ASE requirement is an AND condition with sDA in Option 1, exceeding 10% means Option 1 earns no points, at either the 2-point or the 3-point sDA level. Design teams must control ASE while maintaining sufficient sDA coverage. Four interventions commonly reduce ASE without cutting sDA:

• Exterior overhangs and fins block direct sun on south and west elevations.
• Light shelves redirect daylight toward the ceiling, increasing penetration depth without adding direct solar exposure.
• Selective glazing by orientation: higher visible light transmittance on north-facing glass combined with lower transmittance on south and east reduces direct sun.
• Window-to-wall ratio reductions on east and west address low sun angles that drive ASE accumulation.

Because ASE is part of Option 1 only, a project that cannot meet it may evaluate Option 2 or Option 3, which do not require ASE modeling.

What daylight credit mistakes should teams avoid?

Four errors to avoid on EQ Credit Daylight.

1. Failing ASE while meeting sDA. A project exceeding ASE1000,250 of 10% earns nothing under Option 1, even when sDA300/50% reaches 55% or 75%. Run ASE early in design, while shading changes are still cheap.

2. Omitting the glare-control device requirement. The credit requires manual or automatic (with manual override) glare-control devices for all regularly occupied spaces, whichever option is pursued.

3. Using the wrong floor area. All options use regularly occupied floor area (healthcare: the perimeter area determined under EQ Credit Quality Views). ASE uses the regularly occupied area that is daylit per the sDA simulation. Confirm the area definition against the LEED v4 BD+C glossary and the project’s space types before running the model.

4. Mixing up the point scales. The same percentage earns different points in different options: 75% is 3 points in Option 1 (sDA), 1 point in Option 2 and 2 points in Option 3.

Frequently asked questions

What is the sDA threshold to earn 3 points under LEED v4 EQ Credit Daylight?

sDA300/50% of at least 75% of regularly occupied floor area earns 3 points under Option 1 for New Construction. The same option requires ASE1000,250 at or below 10%. A project meeting the 75% sDA threshold but exceeding 10% ASE earns no points under Option 1.

What does ASE1000,250 ≤ 10% mean in practice?

Annual Sunlight Exposure (ASE) measures the percentage of the daylit regularly occupied area receiving 1,000 lux or more for at least 250 hours per year. Keeping ASE at or below 10% is a condition of Option 1, at both the 2-point and the 3-point sDA tier.

Can a project earn the LEED daylight credit without annual simulation?

Yes. Option 2 uses clear-sky illuminance calculations at the equinox (1 point at 75% of area, 2 points at 90%), and Option 3 uses measurements in the finished building (2 points at 75%, 3 points at 90%). Neither requires ASE modeling.

What is the maximum number of points for EQ Credit Daylight?

3 points for New Construction, Core and Shell, Schools, Retail, Data Centers, Warehouses and Distribution Centers and Hospitality (Option 1 at 75% sDA, or Option 3 at 90% of area). Healthcare projects can earn up to 2 points.