Site Lighting Photometric Plan: Levels, Uniformity & Spill
A site lighting photometric plan shows how exterior light will perform across drive lanes, walks, entries, plazas and related paved areas before fixtures are installed. It uses IES photometric data for the selected luminaires to calculate point-by-point foot-candle (fc) or lux values on the site.
Site lighting is broader than a parking-only study. One commercial exterior often combines parking, circulation, building approaches, loading zones and property-line limits in the same model. The plan helps the owner, engineer and reviewer see whether the layout meets the project targets—and where dark spots, glare or spill need a change—before poles and luminaires are ordered.
For the overall process, see our photometric plans overview and simple guide to photometric analysis.
What a Site Lighting Photometric Plan Covers
A site lighting photometric plan models the commercial exterior as a whole: drive lanes, walks, entries, plazas, service yards and other paved areas that share the same fixture family or pole layout. That differs from a parking-only study, which focuses mainly on stalls and drive aisles. Parking is often included, but the site model can go further when the reviewer or owner needs one coordinated picture of levels across the property.
Typical plan content includes:
- Fixture and pole locations with mounting heights and arms
- Point-by-point foot-candle (or lux) values on defined calculation areas
- Average, minimum and maximum illuminance
- Uniformity ratios (such as Avg/Min)
- Contours / false-color when useful
- Property-line or spill notes when required
If you are comparing a parking-focused package to a full site package, our parking lot photometric plan post explains how those studies are scoped. For help reading grids and statistics on the finished sheet, see how to read a photometric plan.
When You Need One
You typically need a site lighting photometric plan when a permit or plan review asks for calculated exterior levels, when you are redesigning an existing layout, when you are swapping fixtures and need to confirm performance still holds, or when neighbor spill complaints force a documented look at property-line values.
Owners and contractors also use the plan before ordering poles and luminaires so dark spots, over-lit entries or awkward pole spacing show up on paper instead of after concrete is poured. Reviewers may ask for the same model with spill notes or contours so the submittal matches local exterior lighting criteria.
Targets That Usually Matter
Most projects track average and minimum foot-candles by zone, uniformity (often Avg/Min), mounting height and, when required, property-line or spill limits. Walks, drive lanes, entries and parking stalls can each carry different targets. A loading zone may need a higher minimum than a remote drive aisle; a plaza may be judged more on evenness than peak brightness.
There is no single national foot-candle number that fits every commercial site. Owner standards, municipal codes, campus guidelines and the AHJ’s review checklist set the criteria for that job. Use project-specific values from the drawings, the lighting ordinance or the reviewing agency—not a generic chart treated as universal.
Mounting height, arm length, optic type and pole spacing all interact with those targets. Raising poles can stretch coverage but may increase glare or spill if optics and aiming are not matched to the layout. The photometric model is where those tradeoffs get checked against the numbers you are trying to hit.
What’s on the Drawing
A typical site lighting photometric drawing shows calculation grids over the defined areas, a fixture schedule (type, wattage or lumen package, optic, mounting height, arm), pole and fixture locations, and summary statistics for average, minimum, maximum and uniformity. Contours or false-color views are added when they make dark patches or hot spots easier to see at a glance.
When spill or property-line limits apply, the sheet may include notes or a perimeter calculation strip so reviewers can see values at or beyond the lot line. Labels for north, scale and the calculation planes (usually grade for paved areas) keep the package readable for both design and permit review. Learning the symbols and stats once makes later sheets faster to check—again, how to read a photometric plan walks through the common elements.
Common Layout Mistakes
Over-lighting building entries while drive aisles stay dark is a frequent mismatch: more fixtures or higher lumen packages at the door do not fix a sparse pole pattern in the lanes. Ignoring setbacks and property-line limits can push spill values past what the ordinance or neighbor agreement allows, even when parking averages look fine on paper.
Other common issues include mixing optics without rechecking the grid, assuming one mounting height works for every zone, and spacing poles for cost before confirming minimums and uniformity. A site model that includes walks, entries and the perimeter—not only stall centers—catches those problems earlier, when relocating a pole or changing an optic is still inexpensive.
What to Send Us
To start a site lighting photometric plan, send a scaled site plan (CAD preferred when available), mounting heights and arm info, fixture cut sheets or IES files when you have them, project location and any known lighting criteria from the owner, engineer or AHJ. If fixture types are still open, note the candidates so the model can reflect the intended family.
Missing pieces are normal. Scope review identifies what is needed before modeling starts.
Pricing and Next Step
From $220 depending on site size, number of zones, fixture types and whether spill documentation is required. Confirm scope before payment so the calculation areas, criteria and deliverables match what you need for design or permit.
For a clearer sense of what drives cost, see how much a photometric plan costs. When you are ready:
Get a Professional Photometric Plan →
Frequently Asked Questions
What is a site lighting photometric plan?
It is a calculated exterior lighting study that predicts foot-candle levels, uniformity and related performance across a commercial site using IES fixture data and the project geometry.
Is site lighting the same as a parking lot photometric plan?
Not always. Parking is often part of site lighting, but a full site study can also cover walks, entries, plazas, service areas and property-line conditions.
How many foot-candles do I need for site lighting?
It depends on the zone, owner standards and local rules. Use project-specific criteria; do not treat one national number as universal.
Can a photometric plan reduce light spill?
Yes. Optics, mounting, shielding and layout can be tested in the model before installation so perimeter values stay within the limits you are targeting.
What files do you need to start?
A scaled site plan, mounting information, fixture data or IES files when available, project location and any known lighting criteria.