COMMUNITIES AND STATES ARE INCREASINGLY RECOGNIZING THE BENEFITS OF establishing some regulation for outdoor lighting. The move may be prompted by citizen complaints about poorly designed installations, a desire to save energy, or an awareness of losing sight of the night sky. Exterior lighting regulation is also finding its way into many energy codes and regulations such as California's Title 24 and ASHRAE's 90.1-2004. Even the United States Green Building Council's (USGBC) Leadership in Energy and Environmental Design (LEED) rating system has a credit for reducing light pollution.

For all these reasons, there is a need for a technically sound model lighting ordinance that communities can adopt and that is understood industrywide between lighting designers, engineers, contractors, manufacturers, and community officials. The Model Lighting Ordinance (MLO) is currently being developed by a joint task force of the International Dark-Sky Association (IDA) and the Illuminating Engineering Society of North America (IESNA) to be this technically sound document.

If all goes well, the MLO will be available for public review during summer 2007. Watch for announcements from IDA and IESNA when input will be requested. IDA will have public review announcements on its website (, its E-Newsletter, and it will also issue press releases. Public review comments can be electronically submitted on The IESNA will also make announcements to its members via its website ( and to the committees about the public review process. This public review process is open to any interested party.

BACKGROUND Hundreds of lighting ordinances exist, varying widely in complexity and technical soundness. Many of these ordinances require planners and enforcement officers to be knowledgeable in lighting equipment, measurements, and calculations. As a result, the ordinances are often not enforced, and communities are not achieving the desired results.

The IDA/IESNA Task Force was formed with equal representation from both organizations. It is composed of lighting designers and engineers, dark-sky advocates, manufacturers, a utility representative, a city planner, and an illuminating engineering professor. This diverse group of people has expertise in all of the areas considered crucial for a successful and defensible lighting ordinance.

PROJECT GOALS AND OBJECTIVES A model ordinance must be easily understood by audiences from the technical adept to the general public. Striving for sound simplicity has been the overall goal. The simpler it is, the greater the chance that it will be understood, adopted, and enforced.

Other critical goals are:

  • Adaptability to a variety of communities from small to large, rural to metropolitan
  • Minimizing sky glow and light trespass
  • Accepted by environmentalists and manufacturers of lighting equipment
  • Simple to use and understand, yet technically sound
  • THE ORDINANCE DETAILS The ordinance deals with all private property exterior lighting, including residential properties. A separate ordinance will be developed to address roadway and other right-of-way properties. Sections on streetlights and signs will be added in the MLO in future revisions. The main sections of the MLO will include definitions, regulations for nonresidential and residential lighting, and special permits. The emphasis throughout the reference document is on minimizing light trespass and glare and on environmental sensitivity, with due regard to safety issues and good lighting design. (As the MLO is still a work in progress, some sections may change.)

    FRONT-END SECTIONS The first sections of a lighting ordinance (preamble, applicability, definitions, etc.) help set the stage for the lighting ordinance details that follow. This portion of an ordinance needs to be community-specific to ensure community buy-in.

    USE OF LIGHTING ZONES Lighting zones (LZ) are used to assign ambient lighting designations to different area use types, such as single-family residential or a 24-hour entertainment district. Lighting zones vary in ambient lighting: no light (LZ0), low (LZ1), moderate (LZ2), moderately high (LZ3), and high (LZ4). Many small communities may use only one zone (such as LZ1) to simplify enforcement and compliance. Large metropolitan areas may need to use all lighting zones.