McHenry County, IL Outdoor Lighting: Dark Sky Rules (2026)

60 Site Development Standards. Subsection A requires any new permanent lighting installed for a commercial or industrial use in the unincorporated county to use a fully shielded fixture, one positioned so the bulb or its polished reflective surface cannot be seen directly through a residential window. 020 as one where all light rays, direct or reflected, are projected below a horizontal plane running through the fixture's lowest light-emitting point, meaning no light escapes upward or sideways into the sky or a neighbor's yard. Subsection C carves out non-permanent lighting, allowing it without shielding as long as it runs under a temporary use permit or is primarily decorative, such as a holiday display.

040(D) folds exterior lighting compliance into the same review as noise, heat, and glare, and separately bars any commercial or industrial glare or flickering from being detectable off the lot where it originates. The Zoning Enforcement Officer reviews shielding compliance at the building/occupancy permit stage for new commercial and industrial construction, and can order a fixture retrofitted if a resident complains that a bulb is visible through a bedroom or living room window. Because the rule sits in the zoning ordinance, it applies countywide to unincorporated parcels regardless of underlying zoning district, but does not reach the cities and villages within county boundaries that maintain their own lighting standards.