The Shrinking Energy Footprint
One is the feasibility of providing the extra illumination, while remaining within the ever-shrinking lighting energy footprint that is allowed for these areas. For example, the ASHRAE/IES Standard 90.1-2010, adopted by the DOE as the national energy standard, has reduced the allowable watts per square foot for stairways to 1 W/f².

The improved efficiency of available light sources, such as the light emitting diode (LED), and the continuing improvements in the optical systems now found in fixtures make it increasingly possible to meet the seemingly disparate goals of increasing illumination levels, while decreasing the total energy used to provide the illumination. An LED can produce between 50 and 120 lumens per Watt. The new recommended minimum illumination level of ten footcandles is equivalent to 107.6 lumens, well within the amount of illumination that an LED can generate from one Watt. Depending upon the efficiency and distribution pattern of the specific fixture selected, it is certainly possible for an exterior lighting fixture to provide the recommended illumination levels within the more stringent energy footprint.

Preventing Light Pollution
The other concern is the potential for light pollution that the increased levels of exterior illumination could pose.

The International Dark-Sky Association (IDA) is a non-profit organization dedicated to the preservation of the night sky and the elimination of light pollution. The IDA defines light pollution as any adverse effect of artificial light, including sky glow, glare, light trespass, light clutter, decreased visibility at night and energy waste.

The IDA has identified quality, environmentally responsible outdoor lighting as one of the most critical components in their combat of light pollution. To help designers identify and promote the specification of these quality fixtures, the IDA has developed a Fixture Seal of Approval program. The program employs a third party rating system that uses photometric readings to determine the dark-sky-friendly nature of a particular fixture. Over 100 manufacturers currently offer over 300 IDA-approved exterior lighting fixtures and the IDA expects participation in the Fixture Seal of Approval program and the number of approved fixtures to continue to grow.

A Fixture Seal of Approval is not the only way to identify an exterior fixture that would be deemed dark sky friendly. In 2011, the IDA and the IES collaborated on a model code entitled the Model Lighting Ordinance (MLO). The MLO introduced a new classification system for exterior fixtures, referred to as the Backlight-Uplight-Glare (BUG) rating system. This new rating system is intended to replace the cutoff classifications, previously used by the IES, where an exterior fixture was identified as full cutoff, cutoff, semi-cutoff, and non cutoff. While the cutoff classification system was initially focused on brightness and glare control, increasing demand for control of uplight and light trespass led the IES to determine that a more comprehensive rating system was necessary and so the BUG rating system was developed.

Evaluating Options for Illuminating Exterior Steps, Ramps, and Paths of Egress

Four solutions that can be used to provide exterior illumination on steps, ramps, and paths of egress are step lights, bollards, pedestrian pole lights and illuminated handrails. These solutions can vary dramatically in the size of the light distribution pattern and the possibility that environmental elements may totally obstruct the illumination from the fixture. There are also notable differences in the possibility that the fixture could cause glare in the exterior environment and the overall efficiency of the system.

Step Lights

Steps lights are a common solution used to illuminate steps in both indoor and outdoor applications. These light fixtures are small and located in the steps or in the walls at step level. Step lights are typically designed to illuminate a relatively small area near the fixture. They come in a variety of shapes and finishes and are available in a wide range of light sources, including compact fluorescent (CFL), metal halide, halogen, and LED. The availability of highly efficient light sources, such as LED, indicates that step lights are good candidates to be able to provide increased levels of illumination, without exceeding allowable energy limits. While there are step lights that provide illumination levels that exceed the current requirement of 1fc at the floor surface, the products available to provide 10fc at the floor surface may be limited.

Intense Lighting Photo courtesy of Intense Lighting

Maintenance Considerations
Many of these step light fixtures have gaskets. Over the years, maintenance personnel routinely ruin, lose, or discard the gasket, allowing water to seep into the fixture and ruin the electrical components inside the fixture housing.

Potential Obstruction
One of the greatest weaknesses of the step light solution is that the light from these fixtures can be blocked by any obstacle on the steps. People walking up the stairs holding onto a handrail would potentially walk close enough to block the light with each step. Also, any debris on the steps, such as snow or leaves piled along the wall would prevent the step lights from illuminating the steps as intended.

Bollards

Bollard lighting fixtures are short, vertical posts often used to illuminate exterior steps, ramps, and paths of egress. Typical lighting distribution patterns of bollard lighting fixtures are much larger than the distribution patterns provided by step lights. The larger distribution pattern enables bollards to be spaced further apart than step lights, while still providing the necessary level of illumination on the walking surface.

85 4th Ave: New York, New York Photo courtesy of Intense Lighting

Bollards are available in a variety of materials and with a wide range of light sources, including CFL, incandescent, metal halide, and the highly efficient LED.