Alliance for Lighting Information

A Misleading Example of Outdoor Lighting

by Jefferey F. Knox

I have seen this photograph shown under different headings such as "Low Glare Auto Dealership" and "Model Auto Dealer Lighting". This is a photograph (from LD+A April 2003 page 48) of the Ferrari of Denver dealership on County Line Road that sells Ferrari, Rolls Royce, Maserati, etc. The combination of this photograph - seen in numerous previous documents - along with different associated captions is quite misleading. It is implied that this is the type and quantity of lighting that all auto dealerships should install.

This dealership, however, is not your typical auto dealer. First, the dealership is not open past 6:00 pm. Second, the dealership does no outdoor display of their vehicles; they don't leave $100,000 plus automobiles outside no matter how bright the light. All of their stock is housed in the showroom or in enclosed storage areas. Thirdly, assessing glare from a photograph is difficult if not impossible especially when there are no exterior glare sources in the frame. For all we know from this photograph this parking lot could be lighted with wallpacks on poles outside the image boundaries! Additional photos of this site can be seen below.

The exterior lighting shown in this photograph is for the customer parking lot and security. The illuminance levels measured on the site ranged from 20.2 footcandles to 0.5 footcandles in the customer parking lot. This is a 40 to 1 max to min uniformity ratio. The IESNA recommends no more than a 20 to 1 ratio. There was 34 footcandles measured on the ground under the entry canopy to the showroom. In addition, the interior of the building is illuminated in excess of 60 footcandles all night long. As the showroom is mostly glass that light is bouncing off the light colored floor and brightly colored automobiles through the glazing and out into the environment. It would take a lot of parking lot to equal the light pollution generated by this building.

With these facts, one can assume that the caption author feels that good parking lot lighting criteria would be: 0.5 footcandles minimum with a 40 to 1 maximum to minimum uniformity using cutoff luminaires on 20 to 25 foot poles. As for this being a model auto dealership, well if all cars cost $100,000 or more then all dealers could afford to house all of their stock indoors. This would do away with all the dreaded over lighted auto lots. Most of us however could not afford to drive. Ferrari, Maserati, Rolls Royce, Lamborghini, and Bentley are haute couture of the automobile industry - you don't find Vera Wang designs for sale at K-Mart, you find Martha Stewart! This auto dealer is the auto industry's equivalent to a House of Dior boutique.

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