The latest research shows that at least 10% of all outdoor lighting, even fully shielded lighting, ends up creating light pollution, according to the International Dark-Sky Association (IDA). Many communities across the U.S. have tried to deal with light pollution or some facet of it–sky glow, light trespass and, more rarely, glare–with a patchwork of thousands of lighting ordinances, many of them written by non-lighting people.


Three years in the making, a Joint Task Force between the Illuminating Engineering Society (IES) and IDA have completed a long-awaited Model Lighting Ordinance (MLO), which has been posted as a 26-page PDF document on the IDA website for public review and comment.

“Like many communities who have written their own ordinances, we thought it would be easy and in fact, the MLO has taken much longer than we thought it would,” said Denis Lavoie, Task Force co-chairman. “We worked through some challenging issues related to sky glow and glare in order to have a process that has technical credibility. The result is an ordinance that provides the flexibility for an installation to be judged based on the lighting equipment used or the characteristics of light emitted from a site.”

The MLO offers a single generic outdoor lighting ordinance, written in code language for easy adoption into community codes and bylaws, that can be adapted to any community through the use of five Lighting Zones of differing stringencies, which tailor the MLO to address local needs and preferences. A prescriptive system is included to regulate typical lighting installations using a new rating system called BUG (Backlight-Uplight-Glare), which is designed to prevent excessive lighting and permit easy plan review and field inspection. There is also a computer analysis option for complex lighting installations, which applies the latest research findings with respect to glare, skyglow, and light trespass and restricts designs to appropriate limits of off-site impact.

The MLO is also consistent with the California Title 24 outdoor lighting energy code, the next generation of the IES’ Recommended Practice for Outdoor Environmental Lighting, and the next generation of ASHRAE/IES 90.1 and IECC energy codes. It is being submitted to the US Green Buildings Council (USGBC) to be used for the LEED system Sustainable Sites Light Pollution Reduction Credit.

You don’t have to be a member of IES or IDA to comment on the draft MLO. Please read the MLO and share your ideas. Public review closes Friday, April 10, 2009.

“This MLO will permit all of the lighting recommendations of the IES to be met with currently-available lighting equipment,” said Task Force co-chairman James Benya. “For most situations, designs using well-shielded luminaires and good design practice will have no problem complying.”

“We studied hundreds of lighting ordinances as part of this work,” said Task Force member Naomi Miller. “The MLO is the only ordinance that combines what has been learned from recent glare and skyglow research with the realities of practical application.”

A companion “User’s Guide” to the MLO is also in development for release with the final version of the MLO. IDA is already looking into companion model regulations for city street lighting, signs and other causes of light pollution.

Click here to learn more about the MLO and how to comment on it.

Click here to read the November, 2008 National Geographic Magazine cover story, “Our Vanishing Night” by Verlyn Klinkenborg.