Commercial Lighting Power Density Under Title 24
The 2025 Standards give two ways to set allowed indoor lighting power. The Complete Building Method uses one watts-per-square-foot figure for a whole building or tenant space of a listed type. The Area Category Method sets a figure for each primary function area and adds them up. Alterations may use either, or the 80 percent and one-for-one routes.
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Complete Building Method
Table 140.6-B gives one figure per building type: office 0.60 watts per square foot, industrial and manufacturing 0.60, restaurant 0.65, parking garage 0.13, and 0.40 for all other buildings. It applies only to a listed building type, only where one use is at least 90 percent of the building or tenant space, and only when the lighting permit covers the entire building or tenant space.
Area Category Method
Table 140.6-C assigns a density to each primary function area and the allowed total is the sum. Examples: office 0.60 above 250 square feet and 0.65 at 250 or less, corridor 0.40, warehouse 0.40, and 0.60 for storage areas used for shipping and handling. For an unlisted area, a reasonably equivalent type may be selected. General lighting power can move between areas up to what another area gives up, but never between conditioned and unconditioned space, and the display, task, accent and similar allotments cannot be traded at all.
What the number is compared with
Compliance means the adjusted installed power, which is luminaire watts counted under Section 130.0(c) less any earned power adjustment factor credit, is no greater than the allowed total. Table 140.6-B prints a retail row at 0.90, yet Section 140.6(c)1A bars retail stores, so confirm retail with the plan checker. The area method in practice is on lighting power allowance.
How an alteration uses the densities
When 10 percent or more of the luminaires in an enclosed space change, Section 141.0(b)2I offers three routes: meet the Section 140.6 power limit, stay at or below 80 percent of it, or make a one-for-one swap in 5,000 square feet or less that lowers wattage by at least 40 percent. The third route needs no density at all, only before and after wattage, so it suits small relights. See lighting alterations and, for a worked case at 0.40 watts per square foot, warehouse lighting retrofit.
Lighting power is documented on NRCC-LTI-E. How tape counts is on LED tape classification; quotes start from the commercial page.
Common Title 24 Questions
- When does a commercial project need Title 24?
- Does an office tenant improvement need Title 24?
- Does a restaurant remodel need Title 24?
- Does a retail tenant improvement need Title 24?
- What plans are needed for a commercial Title 24 report?
- What is an NRCC certificate of compliance?
Frequently Asked Questions
The Complete Building Method needs a listed type with one use making up at least 90 percent of the tenant space; otherwise the Area Category Method applies.
No. Under the Area Category Method each primary function area has its own figure, such as 0.60 for a large office and 0.40 for a warehouse.
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