Minimum horizontal illuminance shall be no lower than 0.2 fc.

Average horizontal illuminance shall not exceed 2.5 fc.

Uniformity ratios are to be used as a guide.

Minimum vertical illuminance shall be measured at 5.0 feet above parking surface at the point of lowest horizontal illuminance, excluding facing outward along boundaries.

For Typical Conditions. During periods of non-use, the illuminance of certain parking facilities should be turned off or reduced to conserve energy. If reduced lighting is to be used only for the purpose of property security, it is desirable that the minimum (low Point) not be less than 0.1 hfc. Reductions should not be applied to facilities subject to intermittent night use, such as apartments, hospitals and active transportation areas.

If personal security or vandalism is a likely and/or severe problem, an increase above the basic level may be appropriate.

High vehicular traffic locations should generally require the enhanced level of illumination. Exits, entrances, internal connecting roadways and such would be some examples.

Increasing the above illuminance is not likely to increase safety and security. Variance requests for higher levels will generally be for "retail" reasons and should not be granted unless shown to be necessary and at an average illuminance not to exceed 3.6 foot-candles.

Certain data above has been summarized from IESNA RP-20-98, titles "Lighting for Parking Facilities."