The three numbers that define every parking lot lighting project
Every parking lot lighting design comes down to three numbers: the foot-candle target (how bright the lot needs to be), the uniformity ratio (how evenly the light is distributed), and the mounting height (which determines how many poles you need and how far apart they go). Get these three right and the rest of the design follows. Get any one wrong and you are either under-lighting the lot, over-spending on fixtures, or failing the inspection.
| Area | Average fc target | Minimum fc | Uniformity (avg:min) |
|---|---|---|---|
| General parking (low traffic) | 1.0 fc | 0.2 fc | 4:1 or better |
| General parking (medium traffic) | 2.0 fc | 0.5 fc | 4:1 or better |
| Enhanced security | 2.0-5.0 fc | 0.5 fc | 3:1 recommended |
| Entrances, exits, driveways | 3.0-5.0 fc | 1.0 fc | 3:1 or better |
| Pedestrian crosswalks | 2.0-3.0 fc | 1.0 fc | 3:1 or better |
| ADA accessible spaces | 2.0 fc min | 2.0 fc | Consistent; no dark spots |
| Parking garage, general | 5.0 fc | 1.0 fc | 10:1 max |
| Parking garage, entry/exit (daytime) | 50 fc | 25 fc | Transition zone for eye adaptation |
Source: IES RP-20 (Lighting Parking Facilities) and IES Lighting Handbook, 10th Edition, Table 26.2. Values are general guidelines; actual requirements vary by jurisdiction. Many municipalities specify higher minimums or lower uniformity ratios than the IES baseline. Always check local codes.
Uniformity matters more than average brightness. A study by the Lighting Research Center at Rensselaer Polytechnic Institute found that parking lot users reported feeling safer and having better visibility with lower average light levels when the light was more uniform (3:1 ratio) compared to higher average levels with poor uniformity (10:1 ratio). Spending money on more lumens does not help if the lot has dark pockets between poles.
Pole height and spacing: the relationship that drives the entire layout
The mounting height determines how far each fixture can throw light, which determines how far apart the poles can be, which determines how many poles the project needs. The rule of thumb: space poles at 2 to 3 times the mounting height.
| Pole height | Typical spacing range | Typical lumen range per fixture | Best for |
|---|---|---|---|
| 15-20 ft | 30-50 ft | 12,000-20,000 lm | Small lots, residential, areas with height restrictions |
| 20-25 ft | 50-70 ft | 20,000-30,000 lm | Most commercial parking lots. The sweet spot for cost, coverage, and code compliance. |
| 25-30 ft | 60-80 ft | 25,000-45,000 lm | Large commercial and retail lots where fewer poles reduce infrastructure cost. |
| 30-40 ft | 80-120 ft | 40,000-60,000 lm | Industrial facilities, large campus lots. Requires high-output fixtures. May be prohibited by local height limits. |
These spacing values assume the fixture has an appropriate distribution type for the mounting position (see next section). A narrow-distribution fixture spaced at the wide end of these ranges will produce dark spots between poles. A wide-distribution fixture spaced at the narrow end wastes money on unnecessary poles.
Check the local height limit before specifying poles. Many municipalities restrict parking lot pole heights to 20 or 25 ft maximum. Some restrict even further in residential-adjacent zones. The height limit affects everything downstream: fixture lumen requirements, number of poles, total project cost. Discovering the height limit after the bid is submitted means reworking the entire layout.
Light distribution types: choosing the right optic for each pole position
LED area lights come with different optical distributions that control where the light goes. The IES classifies these distributions by type (I through V). Two of them matter for parking lots.
Forward throw, asymmetric
Throws light forward and to the sides in a wide, asymmetric pattern. Does not throw light behind the pole. Ideal for perimeter poles where the fixture faces inward toward the lot and there is a property line, building, or roadway behind the pole where light trespass is not wanted.
Circular, symmetric
Spreads light in a circular pattern equally in all directions. Ideal for interior poles in the middle of the lot where the fixture needs to light the parking area on all sides of the pole. Also suitable for square intersections or turnaround areas.
The standard layout approach: Type III on the perimeter, Type V in the interior. Perimeter poles push light into the lot without spilling it beyond the property line. Interior poles distribute light evenly to all four quadrants around the pole.
Dark sky compliance, light trespass, and the local codes that override everything
Local ordinances can be more restrictive than IES guidelines on every dimension: pole height, light trespass, uplight, CCT, and even fixture style. Here is what to check before finalizing the design.
| Regulation type | What it controls | Common requirements |
|---|---|---|
| Maximum pole height | How tall the poles can be, measured from finished grade to top of fixture. | Typically 20-25 ft for commercial lots. Some historic districts restrict to 12-15 ft. Industrial zones may allow 40 ft. |
| Full cutoff / zero uplight | How much light the fixture emits above the horizontal plane. | Full cutoff means zero light above 90 degrees. Required in most dark sky ordinances. All modern LED area lights with flat lenses meet this. Adjustable-tilt fixtures must be aimed correctly to comply. |
| BUG rating | Backlight, Uplight, and Glare ratings per IES TM-15. More granular than simple cutoff classification. | Specific BUG maximums depend on the lighting zone (LZ0 through LZ4). Higher lighting zones allow more. The BUG rating is listed on the fixture's spec sheet. |
| Maximum CCT | Color temperature of the light. Lower CCT = less blue light scatter = less skyglow. | Dark sky ordinances commonly cap at 3000K. Some wildlife-sensitive areas require 2200K or amber (590nm). Standard commercial lots: 4000K-5000K unless restricted. |
| Light trespass | How much light spills onto neighboring properties. | Measured in fc at the property line. Limits range from 0.0 fc (zero trespass) to 1.0 fc depending on zone. Type III distribution on perimeter poles is the primary tool for controlling trespass. |
| Fixture style | The appearance of the fixture and pole. | Some historic districts or planned communities mandate specific fixture styles (e.g., "antique globe/coach style"). Check before specifying a standard shoebox or area light. |
Jarvis JSAL-G2 Series area lights ship with CCT-selectable options (4000K/5000K), full cutoff optics, and Type III or Type V distribution. For dark sky-restricted projects, the 4000K setting provides compliance in most ordinances. For areas requiring 3000K, confirm the fixture offers that CCT option or specify accordingly.
Exterior lighting controls: what the energy code requires
ASHRAE 90.1-2022 expanded exterior lighting control requirements significantly. A simple photocell (on at dusk, off at dawn) is no longer sufficient on its own. The code requires two independent reduction strategies operating together.
Requirement 1: Schedule-based reduction. All exterior lighting must be capable of reducing to at least 50% of full power based on a time-of-day schedule. This means fixtures need to be connected to a time clock, astronomical clock, or a networked lighting control system with scheduling capability.
Requirement 2: Occupancy-based reduction. All exterior lighting must also reduce by at least 50% within 15 minutes of the area becoming unoccupied. A single control zone cannot exceed 1,500W of controlled lighting.
Both requirements must be met. A photocell handles on/off at dusk/dawn but does not provide mid-night dimming (schedule) or vacancy response (occupancy). Meeting both requirements typically means either discrete sensors (photocell + time clock + occupancy sensor per zone) or an NLC system that provides all three functions in one platform.
For a detailed breakdown of all ASHRAE 90.1 lighting requirements, see the energy code compliance guide. For utility rebate opportunities on the controls layer, see the rebate guide.
Worked example: a 200-space commercial parking lot
The project
Given: A 60,000 sq ft (300 ft x 200 ft) commercial parking lot for a retail center. Medium traffic. 2 fc average target with 0.5 fc minimum. Local code limits poles to 25 ft. No dark sky restrictions. Using 150W LED area lights at 22,000 luminaire lumens each. 4000K/5000K selectable. Type III distribution for perimeter, Type V for interior.
= 60,000 x 2 / 0.35 = 342,857 lumens
342,857 / 22,000 lm per fixture = 16 fixtures (minimum)
Layout
Perimeter poles: 10 poles along the three open edges (not the building side) at approximately 60 ft spacing. Type III distribution, aimed inward. These handle the property-line edge and push light into the lot.
Interior poles: 2 poles centered in the lot, approximately 100 ft apart. Type V distribution for 360-degree coverage.
Building-side lighting: The building wall provides the fourth edge. Wall-mounted wall packs or building-mounted area lights illuminate the row closest to the building. 4 fixtures at 8,000 lumens each.
Total: 12 pole-mounted area lights + 4 building-mounted fixtures = 16 fixtures.
Operating hours (dusk-to-dawn avg): 4,100 hrs/yr
Annual energy: 2.4 kW x 4,100 hrs = 9,840 kWh
At $0.12/kWh = $1,181/year operating cost
Compared to the 400W MH equivalent (16 x 460W incl. ballast):
Old: 7.36 kW x 4,100 hrs = 30,176 kWh = $3,621/yr
Savings: $2,440/year (67% reduction)
With a prescriptive rebate of $125 per DLC-listed area light: 16 x $125 = $2,000 rebate. Add NLC incentives if the project includes networked controls. Payback is typically under 3 years after rebates and energy savings combined.
Layout is a representative example. Actual fixture count and spacing must be verified with a photometric layout using the specific fixture's IES file. Ground utilance of 0.35 is a typical approximation for open parking lots. For a detailed explanation of the lumen method and ground utilance, see the lumens guide.
Parking lot site survey checklist
Walk the lot at night before designing the layout. Bring a light meter, a tape measure, and a camera.
| # | Check item | Why it matters |
|---|---|---|
| 1 | Measure the lot dimensions (length, width, total sq ft). | Required for lumen calculation and pole count estimate. |
| 2 | Identify existing pole locations, heights, and foundation types. | Reusing existing pole bases saves excavation cost on retrofits. |
| 3 | Note the electrical service location and available circuits. | Determines where conduit runs go and whether panel upgrades are needed. |
| 4 | Photograph the lot at night from multiple angles. | Documents existing dark spots and light distribution for the proposal. |
| 5 | Identify property line locations. | Determines where Type III distribution is needed to prevent light trespass. |
| 6 | Check for trees, signs, or structures that could block light or create shadows. | Obstructions may require additional poles or adjusted fixture positions. |
| 7 | Note entrance, exit, crosswalk, and ADA space locations. | These areas need higher foot-candle levels (3-5 fc) than general parking. |
| 8 | Confirm local pole height limit, CCT restriction, and dark sky ordinance. | Determines fixture selection and maximum pole height before design starts. |
| 9 | Determine operating hours and whether the lot is used 24/7 or has off-peak periods. | Affects the control strategy (scheduling, dimming, occupancy response). |
| 10 | Confirm whether the utility offers exterior lighting or NLC rebates. | The rebate may cover 20-30% of fixture cost and influence fixture selection (DLC listing required). |
Frequently asked questions
How many foot-candles does a parking lot need?
For a standard commercial lot, target 1-2 fc average with a minimum of 0.5 fc. Entrances, exits, and crosswalks need 3-5 fc. Enhanced security areas may need up to 5 fc. IES RP-20 recommends a uniformity ratio (average to minimum) of 4:1 or better. Uniformity often matters more than raw brightness. Check local codes for specific requirements.
How far apart should parking lot light poles be?
Space poles at 2 to 3 times the mounting height. For 25 ft poles, that means 50-75 ft. Exact spacing depends on the fixture's lumen output and distribution type. A photometric layout using the fixture's IES file is the only way to confirm the spacing meets foot-candle and uniformity targets for the specific lot geometry.
What mounting height should I use?
20-25 ft is the most common range for commercial lots. Taller poles (30-40 ft) reduce the total number needed but many municipalities cap at 20 or 25 ft. Higher mounting requires higher-lumen fixtures to maintain ground-level foot-candles. Always check the local height ordinance before specifying.
What is the difference between Type III and Type V distribution?
Type III throws light forward and to the sides (asymmetric), ideal for perimeter poles where you do not want light behind the pole. Type V spreads light in a circular pattern (symmetric), ideal for interior poles that need to light all sides. Most layouts use Type III on the perimeter and Type V in the center. The Jarvis JSAL-G2 is available in both distribution types.
What are the ASHRAE 90.1 exterior controls requirements?
All exterior lighting must reduce by at least 50% based on both a schedule AND occupancy sensing. Occupancy reduction within 15 minutes of vacancy. Max 1,500W per occupancy zone. A photocell alone does not satisfy the code. The project needs either discrete sensors (photocell + time clock + occupancy) or a networked lighting control system. See the energy code guide for the full breakdown.
What does dark sky compliant mean?
Full cutoff fixtures (zero uplight above horizontal), CCT capped at 3000K or lower, and fixed mounting arms. Requirements come from the International Dark-Sky Association and are adopted by many municipalities as local ordinances. Some wildlife-sensitive areas require 2200K or amber (590nm) light. Check the local ordinance, not just IDA guidelines, for the specific restrictions that apply to your project.
