For about 50 years, there have been growing concerns among scientists about “light pollution,” a term given to excessive, wasteful outdoor lighting. With too much sky bound illumination at night, it’s becoming increasingly difficult to observe the stars. That’s true for all people, including astronomers using sophisticated monitoring technology.
In response, many states (19 at last count) have passed state-level lighting regulations aimed at reducing the impact of exterior fixtures at night. Many cities, municipalities and neighborhoods also have their own light pollution ordinances in place, so compliance is required at multiple levels.
In 1988, the International Dark-Sky Association (IDA) was founded by astronomers to advocate for less light pollution. The IDA reviews lighting sources for their light pollution output, giving their seal of approval to fixtures that facilitate a darker sky. The IDA’s guidelines are good ones to follow in order to reduce “skyglow” and other effects of too much exterior illumination.
What Are The Negative Effects Of Too Much Night-Time Light?
In urban areas and in their outlying communities, too much night-time illumination is associated with sky glow. Skyglow is that orangish haze that envelopes cities at night, the result of upward-aimed lighting contacting dust particles in the air. Skyglow can also be caused by natural sources, like snow, and can also be the result of light reflecting off the ground.
In an area where skyglow is present, the levels of ambient illumination can be up to 10 times higher than normal.
There are a number of problems associated with this phenomenon, including:
- Disrupted circadian rhythms – We’re adapted to a regular day and night cycle that can be adversely affected by sky glow. Specifically, it’s our circadian rhythms – the ones that regulate wakefulness and sleepiness – that suffer. This can result in reduced sleep for people, which can cause problems with human health.
- Altered animal behavior – Animals are also affected by skyglow, especially among animals that rely on light for navigation, like birds. Migratory patterns, predator and prey behaviors and avoidance behaviors are all disrupted by excessive night-time illumination.
- Reduced agricultural output – Not even plants can escape the effects of skyglow. Plants, including agricultural crops, require extended periods of darkness to efficiently perform photosynthesis. If skyglow is present, this can impact plant growth and reduce agricultural output for farms near urban areas.
There’s also the aesthetic impact of skyglow, as it shields the full night sky from view.
What Lighting Fixtures Can Help Minimize Light Pollution?
The IDA’s guidelines are a good place to start if minimal light pollution is the goal. To reduce the amount and impact of skyglow, the following lighting features are recommended:
- Full cutoff fixtures – One of the biggest ways to reduce light pollution is with the use of full cutoff fixtures. Full cutoff fixtures are those that are shielded from emitting above the horizon. Full cutoff fixtures should also output 10 percent or less of their full lumen capacity between 80 and 90 degrees above nadir.
- Night-time off switching – The opposite of dusk to dawn operation, the IDA recommends any nonessential lighting be automatically switched off at night. This can be done with the use of photocells or timers, but the point is the same. If the light isn’t needed at night, leaving it on does nothing but exhaust the fixture and fill the sky with excess illumination.
- Occupancy controls – Occupancy controls can further reduce light pollution while ensuring those critical night-time fixtures are still there when needed. Occupancy controls detect motion or heat, and when they do, they can automatically switch nearby lights on or increase their output to improve visibility and safety. If no one is nearby, occupancy controls can dim the lights or switch them off altogether.
- Low wattage lights – The IDA recommends low wattage sources for outdoor lighting, as low wattage lamps output less intense levels of illumination. Only use the wattage you need to achieve sufficient light levels. Anything more will be a waste, of light and of money.
LED Lighting Can Also Help Darken The Night Sky
There are numerous advantages associated with LED lighting, some of which make it easier to facilitate a dark sky approach. Some of those advantages include:
- Energy efficiency – LED lighting is the most energy efficient on the market. With its excellent efficiency, LED lighting possesses a superior watt-to-lumen ratio. You get more light per unit of energy, in other words.
This enhanced efficiency is pronounced at the system level, because LEDs suffer fewer lighting losses. LED lighting is directional by virtue of its engineering, so it can be aimed without the use of expensive and bulky reflectors. That also means less light is emitted into the sky and more is aimed at the ground.
- Color temperature options – The IDA recommends fixtures with lower color temperatures (3000K or less). At the low end of the color temperature spectrum, there’s less blue light emitted by the fixture and more “warm” tones. Warmer lights create less glare and are generally perceived to have lower levels of brightness. This can, in part, reduce light pollution in the environment.
- Controllability – LED lights are also the most controllable on the market, as they are engineered using reliable circuitry. This circuitry is far easier to control than a filament or gas chamber, so you can dim an LED, attach a photocell to it, pair it with occupancy sensors, and generally control the fixture however needed to reduce waste.
These are just a few reasons why residential and commercial property owners are making the switch to LEDs. There are many more, including extended lifespan, excellent lighting quality and enhanced durability.
Dark sky ordinances are enforced at many levels, so minimizing your lighting trespass is essential for compliance. Choose a lighting company with a large variety of lighting products that are compatible with dark sky initiatives, no matter what your lighting needs are. If you’re unsure where to begin with your exterior lighting project, we can guide you through it with expert photometric analysis.