Lighting Power Density
Interior lighting power allowance by the Building Area Method.
Example
You enter
- Area (ft²) 1000
- Occupancy class office
- IECC edition 2021
You get
- Interior lighting power allowance 640 W
- Allowance 0.64
Checked against published worked examples from: ICC / ASHRAE.
Details, formula, and sources
ScopeFloor area times the IECC 2024 lighting power density for the building type (office 0.62 W/ft2), with the IECC 2021 table (office 0.64, the same as ASHRAE 90.1-2019) as an edition option. The adopted energy code edition governs.
Formula or tableInterior lighting power allowance = area × LPD of the building area type (Building Area Method). An energy-code limit on installed lighting, not the NEC Table 220.42(A) unit load used to size the service.
Source and editionIECC 2024 Table C405.3.2(1), with the IECC 2021 table (identical to ASHRAE 90.1-2019 Table 9.5.1) as an edition option.
Free accessFree read-only access at nfpa.org/freeaccess. IECC free read-only at codes.iccsafe.org. ASHRAE 90.1 read-only at ashrae.org.
What governsEstimate. AHJ and licensed electrician govern. Verify against the NEC edition adopted in your jurisdiction.
API field namesarea_ft2, occupancy_class, code_edition, target_W, w_per_ft2
- LPD edition IECC 2024 Building Area Method by default; IECC 2021 / ASHRAE 90.1-2019 on requestdata/electrical/lighting-density.json