Commercial lighting has to stay within an energy budget and include automatic controls, per IECC C405. Interior lighting is limited by a lighting power density (watts per square foot), calculated by the building-area method or the more granular space-by-space method. On top of the power limit, C405 requires controls: occupancy sensors in many space types, automatic shutoff, daylight-responsive controls near windows and skylights, and specific exterior-lighting controls and power limits.
The common mistake is a lighting design that meets the power density but omits required controls — daylighting controls in a perimeter zone, or occupancy sensors where the space type demands them — which shows up in the COMcheck lighting compliance.
Reviewers check the lighting power calculation against the allowance and confirm the required control types are shown on the plans (or reflected in the COMcheck report). Because lighting is one of the three COMcheck compliance areas alongside envelope and mechanical, gaps here hold up energy sign-off even when the fixtures themselves are efficient.
This guide describes the model code for general understanding and is not a substitute for the adopted code and amendments enforced by your local authority having jurisdiction. Verify all figures against your jurisdiction's codes of record.