Lighting is one of the more straightforward parts of COMcheck compliance to understand, but also one of the more common places a commercial submittal falls short — usually because the lighting design wasn't checked against the applicable allowance until late in the process. Understanding how lighting power density works, and where it typically causes problems, helps avoid a lighting section that fails after everything else has already been finalized.
Lighting power density (LPD) measures the total connected lighting wattage per square foot of a given space, expressed in watts per square foot. Every space-use classification carries its own maximum allowable LPD — the applicable code sets a ceiling, and a proposed lighting design needs to fall at or under that number to pass compliance for that space.
COMcheck supports two lighting compliance methods: the building area method, which applies a single LPD allowance across the whole building based on its general use type, and the space-by-space method, which applies individual allowances to each distinct space type within the building. The space-by-space method is more detailed but often more flexible, since it allows higher-wattage spaces (like a retail sales floor) to be offset by lower-wattage spaces elsewhere (like a back-of-house storage area) within the same project.
Because LPD allowances vary meaningfully by space type — a restaurant dining area, a warehouse, and a private office all carry different maximums — misclassifying a space is one of the most common ways a lighting compliance calculation produces an inaccurate result. A space that's actually a specialty retail area but gets classified as generic retail, for example, may be evaluated against the wrong allowance entirely.
Decorative or accent lighting is a frequent culprit, since it's easy to underestimate the cumulative wattage of accent fixtures when focusing primarily on general ambient lighting. High-end retail and hospitality projects, where lighting design is often a significant aesthetic priority, are particularly prone to exceeding LPD allowances if the lighting plan isn't checked against COMcheck early in the design process rather than after fixtures are already selected and ordered.
The most reliable way to avoid a failed lighting section is running a preliminary LPD check during the lighting design phase, before fixtures are finalized — this allows adjustments to fixture selection or layout while there's still flexibility, rather than discovering a compliance problem after the lighting plan has already been finalized and submitted for permit.
Which lighting compliance method is generally more favorable — building area or space-by-space?
Space-by-space is often more flexible since it allows offsetting higher-wattage spaces with lower-wattage ones within the same building, but which method is more favorable depends on the specific project's space mix.
Does decorative or accent lighting count toward the LPD calculation?
Yes — all connected lighting wattage in a space generally counts, including decorative and accent fixtures, which is a common source of underestimated LPD totals in aesthetically driven lighting designs.
When should a lighting design be checked against COMcheck requirements?
As early as possible — ideally during the lighting design phase, before fixtures are finalized, so adjustments can be made without redesigning an already-selected lighting package.
Psychro.Pro runs COMcheck lighting compliance checks early in your design process, helping you catch LPD issues before fixtures are finalized and ordered.Learn more.
