ASHRAE/IES Standard 90.1 is the model energy code governing commercial building lighting in most of the United States. It caps lighting power density in watts per square foot by space type and mandates controls including automatic shutoff, occupancy sensing, and daylight response. Adopted editions vary by jurisdiction.
This page is the code cluster's router — Lighting Power Density lives here as an anchored section so 'LPD by space type' traffic lands on an edition-stamped table. 90.1-2022 space-by-space examples: open office 0.61, corridor 0.41, warehouse 0.43 W/sf; 90.1-2025 tightens shutoff from 20 to 15 minutes.
DOE supports model codes; states and localities adopt and enforce — never 'federal law requires.'
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