5.3 Electric Light Glare Control (L04), Visual Balance (L07) & Electric Light Quality (L08)

5.3 Electric Light Glare Control (L04), Visual Balance (L07) & Electric Light Quality (L08)

Core Exam Takeaway: These three features are about light quality. L04 (2 pt / Core 1 pt) = UGR ≤ 16, relaxed to UGR ≤ 19 for industrial. L07 (1 pt / Core 0.5 pt) = at least three of four balance parameters. L08 (3 pt / Core 1.5 pt) = colour rendering (1 pt) plus flicker (2 pt). Note the numbering: L07 is Visual Balance, not "Visual Balance & Surface Reflectance," and it is not L05.

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Feature L04: Electric Light Glare Control — Optimization (2 pt / WELL Core 1 pt)

Intent: minimize glare caused by electric light.

L04 Part 1 — Manage Glare from Electric Lighting

For all spaces except industrial. Each luminaire meets one of the following for regularly occupied spaces, at light output representative of regular use conditions:

Option 1: Luminaire considerations

• (a) 100% of light is emitted above the horizontal plane (i.e., fully indirect).
• (b) Classified with Unified Glare Rating (UGR) of 16 or lower.
• (c) Luminance that does not exceed 6,000 cd/m² at any angle between 45 and 90 degrees from nadir.

Option 2: Space considerations — UGR of 16 or lower in all regularly occupied spaces.

For industrial spaces, the same structure with a relaxed limit:

• Option 1: meets the all-spaces requirements above, or UGR of 19 or lower.
• Option 2: UGR of 19 or lower in all regularly occupied spaces.

Exclusions: wall wash fixtures and concealed fixtures installed as specified by manufacturer's data, as well as decorative fixtures, may be excluded from meeting the luminaire requirements.

WELL Core guidance: non-leased spaces; an additional point for also meeting requirements in leased spaces.

[!TIP] The distinction between Option 1 and Option 2 is per-fixture versus per-space compliance. Option 1 lets a specifier prove each luminaire's data sheet meets a limit; Option 2 requires a calculated UGR for the room, which accounts for geometry, surface reflectances and observer position. Option 2 is harder to document but forgiving of individual fixture choices.

[!IMPORTANT] Nadir is straight down. The 45°–90° from nadir band in Option 1(c) is precisely the angular zone a seated occupant's eye sweeps when looking across a room — which is why the luminance cap applies there and not at nadir, where the fixture is above the line of sight.

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Feature L07: Visual Balance — Optimization (1 pt / WELL Core 0.5 pt)

Intent: create lighting environments that enhance visual comfort.

L07 Part 1 — Balance Visual Lighting

Option 1: Parameters for visual balance. Ambient lighting in all regularly occupied spaces meets at least three of the following four:

• (a) Horizontal and vertical luminance contrast ratios for an ambient light system are no more than 10 between adjacent independently controlled zones.
• (b) Illuminance uniformity ratio of at least 0.4, or 1:2.5 (minimum light level : average light level), on any horizontal task plane within a space.
• (c) Automatic changes in lighting characteristics — light levels, changes in colour and distribution — take place over a period of 10 minutes.
• (d) The Correlated Colour Temperature (CCT) in each room for similar fixtures is consistent (± 200 K) at any point in time.

Option 2: Design for visual balance. Lighting is designed by a lighting professional and takes into account: luminance ratios on vertical and horizontal adjacent zones; illuminance uniformity on horizontal task planes; changes in lighting characteristics; and colour temperature of lights used.

[!TIP] Requirement (c) is the least intuitive and therefore the most examinable: automatic changes spread over 10 minutes. Abrupt transitions in a tunable or daylight-responsive system read as flicker or failure and provoke complaints; a ten-minute ramp falls below the threshold of conscious notice. Requirement (d)'s ± 200 K is a within-room consistency rule — it does not prescribe a colour temperature, only that similar fixtures agree.

[!TIP] Option 2 is the pragmatic route: engaging a lighting professional who documents consideration of all four topics earns the point without hitting any numeric threshold. That mirrors a pattern across WELL — a performance option and a qualified-professional option for the same outcome.

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Feature L08: Electric Light Quality — Optimization (3 pt / WELL Core 1.5 pt)

Intent: enhance visual comfort and minimize flicker.

L08 Part 1 — Enhance Colour Rendering Quality (1 pt / Core 0.5 pt)

For all spaces except circulation areas. All luminaires — except decorative fixtures, emergency lights and other special-purpose lighting — meet at least one of:

• (a) CRI ≥ 90
• (b) CRI ≥ 80 with R9 ≥ 50
• (c) IES Rf ≥ 78, IES Rg ≥ 100, and −1% ≤ IES Rcs,h1 ≤ 15%

If tunable white lighting is used, the requirements are met at 1,000 K intervals from the lower end (minimum 2,700 K) to the higher end (maximum 5,000 K).

For circulation areas — a relaxed tier. Meet at least one of:

• (a) CRI ≥ 80
• (b) IES Rf ≥ 75, IES Rg ≥ 95, and −7% ≤ IES Rcs,h1 ≤ 15%

L08 Part 2 — Manage Flicker (2 pt / Core 1 pt)

All luminaires in combination with the appropriate controls — except decorative, emergency and other special-purpose lighting — used in regularly occupied spaces meet at least one of:

• (a) Classified as "reduced flicker operation" per California Title 24, tested per Joint Appendix JA-10.
• (b) Recommended practices 1, 2 or 3 as defined by IEEE standard 1789-2015 LED.
• (c) Pst LM ≤ 1.0 and SVM ≤ 1.6 for indoor applications per NEMA 77-2017.

WELL Core guidance for both parts: non-leased spaces; an additional point for also meeting requirements in leased spaces.

+-----------------------------------------------------------------------------+
|                 L08: WHY FLICKER IS WORTH TWICE THE POINTS                  |
|                                                                             |
|   Colour rendering (1 pt) affects how things LOOK.                          |
|   Flicker (2 pt) affects the NERVOUS SYSTEM.                                |
|                                                                             |
|   Temporal light modulation -- even above the ~60-90 Hz flicker fusion       |
|   threshold where it is invisible -- is associated with headache,            |
|   eyestrain, reduced task performance, and in susceptible individuals        |
|   migraine and photosensitive seizure. It is also invisible, so occupants    |
|   cannot report the cause.                                                  |
|                                                                             |
|   Note WELL's phrasing: luminaires "in combination with the appropriate      |
|   CONTROLS". A low-flicker LED module on a cheap phase-cut dimmer can        |
|   flicker badly. The pair is what is tested, not the lamp alone.             |
+-----------------------------------------------------------------------------+

[!IMPORTANT] CRI alone is not enough at the 80 level. WELL accepts CRI ≥ 80 only when paired with R9 ≥ 50. R9 is the saturated red test colour — the one general CRI averaging conceals, and the one that governs whether skin tones and food look healthy. A source can post CRI 82 with a badly negative R9. That pairing rule is one of the Light concept's most reliable exam items.

[!TIP] The circulation-area relaxation exists because corridors and stairwells are transitional: nobody performs colour-critical work there, so CRI ≥ 80 alone suffices with no R9 condition. And note the tunable white rule — compliance must be demonstrated at 1,000 K intervals across the tuning range, so a system that renders beautifully at 4,000 K but poorly at 2,700 K fails.

The three metric families you should be able to distinguish

Add EML / M-EDI (circadian, L03), sDA (daylight, L01 and L06) and VLT (glazing transmittance, L05) and you have the complete metric vocabulary of the Light concept — six families, each attached to specific features.