Outdoor Lighting Zones Explained

Five zones, by surrounding ambient light

• LZ0 — very low ambient. Undeveloped areas of government designated parks, recreation areas and wildlife preserves.
• LZ1 — low ambient. Rural areas as defined by the 2020 U.S. Census, which include single or dual family residential areas, parks, agricultural zone districts and the developed portions of government designated parks, recreation areas and wildlife preserves.
• LZ2 — moderate ambient. Urban areas as defined by the 2020 U.S. Census, where multifamily housing, mixed use residential neighborhoods, religious facilities, schools and light industrial zoning districts may occur.
• LZ3 — moderately high ambient. Urban areas as defined by the 2020 U.S. Census, where high intensity commercial corridors, entertainment centers and heavy industrial or manufacturing zone districts may occur.
• LZ4 — high ambient. No statewide default location; a local jurisdiction decides where it applies.

Table 10-114-A in Part 1 of the 2025 Standards sets these statewide defaults from 2020 U.S. Census Bureau rural and urban boundaries. Under Section 10-114(c) a local jurisdiction may adopt a different zone for an area through a public process, so the zone is a property of the location and not something the applicant picks.

No statewide default area is LZ4

LZ4 describes the most intensely lit environments, a Times Square sort of place. Table 10-114-A lists no default location for it, and Section 10-114(c) lets a local jurisdiction determine where LZ4 applies, so no areas within California fall under LZ4 unless a city or county has adopted it for a district.

That is worth knowing before anyone reaches for it. The zone exists in the table, and in practice a California project is working in LZ0 through LZ3. If a calculation has been built on LZ4 allowances, confirm that the local jurisdiction has adopted that zone for the site.

The allowance follows the zone

Lighting zone determines the outdoor lighting power allowance, lowest in LZ0 and highest in LZ4. The reasoning is about contrast rather than about generosity: in a genuinely dark area the eye adapts and very little light is needed to see well, while in a brightly lit urban setting the same fitting reads as dim against its surroundings.

So the same car park needs materially more power to be usable in LZ3 than in LZ1 — and would be over-lit and intrusive in LZ1 at LZ3 levels.

Why a rural site is the one to watch

Rural areas, including single and dual family residential areas, agricultural districts and the developed parts of parks, recreation areas and wildlife preserves, default to LZ1. A commercial project in or beside one of those can find itself in a much tighter zone than the nearest city, with an allowance that will not support a conventional lighting scheme.

This is not only an energy matter, because dark-sky and habitat considerations are the reason those areas are classified low, but the effect on the compliance calculation is the same. Table 10-114-A also lets a local jurisdiction move some sites up, for example retail stores in a residential neighborhood or a rural town center that operate during hours of darkness can be designated LZ2. The zone has to be established from the location and the local designation rather than assumed from the character of the development.

Establish the zone before designing the scheme

Because the allowance is layered — general hardscape, plus outdoor sales lot and frontage allowances where they apply — the zone sets the base every other allowance builds on. A design laid out first and checked afterwards can be a long way over on a site that turns out to be LZ1 or LZ2, and a quick check with the local planning department settles whether the jurisdiction has amended the default.

Common Title 24 Questions

1. Does replacing commercial lighting trigger Title 24?
2. What is a Title 24 lighting power allowance?
3. What are Title 24 lighting controls?
4. Title 24 for warehouse and high-bay lighting
5. Title 24 for outdoor and site lighting
6. When are automatic daylighting controls required?

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