Choosing Lights To Reduce Light Pollution

Light pollution is a pressing issue, with 99% of people in Europe and the US living under light-polluted skies. The problem stems from poorly targeted, overly bright, and improperly shielded outdoor lighting. To reduce light pollution, it is recommended to use lights with motion sensors, ensure bulbs are covered and facing downwards, and use lower-wattage bulbs. Switching to LED lighting is also a good option as it has a more focused light beam and uses less energy. Additionally, minimizing light usage, reducing decorative lighting, and using lighting controls can help reduce light pollution.

Characteristics of Lights That Reduce Light Pollution

Use downward-facing lights

Using downward-facing lights is a crucial strategy in reducing light pollution. This technique, also known as "cutting off light at the horizontal", ensures that light is directed towards the ground and not upwards into the sky. By angling lighting fixtures downwards, we can illuminate the areas where light is needed, such as roads, streets, and pathways, while minimising light trespass and glare.

Downward-facing lighting is particularly important for streetlights and outdoor lighting fixtures. When light is reflected upwards, it not only contributes to light pollution but also reduces visibility and safety on the ground. By adopting this simple measure, we can improve the efficiency of our lighting systems and reduce wasted light.

To achieve downward-facing lighting, it is recommended to use shades or covers that force the light downwards. These can be part of the original light fixture or purchased separately. LED lighting, for example, is highly directional, making it easier to aim the light where it is needed. Additionally, light shields can be attached to the top and/or sides of light fixtures to focus the light downwards and prevent upward light trespass.

When implementing downward-facing lighting, it is also essential to consider the height and spacing of the lighting units. For instance, in the case of route lighting or bollard lighting for garden paths, using shorter fixtures and spacing them closer together may be necessary to ensure adequate illumination while directing the light downwards.

By adopting downward-facing lighting, we can significantly reduce light pollution, improve visibility, and conserve energy. This simple yet effective strategy is a crucial step towards minimising our impact on the environment and reclaiming the beauty of a starry night sky.

Minimise light use

One of the easiest ways to reduce light pollution is to simply use less light. This can be achieved by reducing the number of lights, only lighting the necessary areas, and keeping lights off for as long as possible.

For example, outdoor lights do not need to be on all night unless there are security concerns. Even then, motion-sensitive lighting can be used to illuminate an area only when movement is detected. Motion sensors can also be added to existing lights to reduce energy use and light pollution.

Indoor lighting can also contribute to light pollution, so it is important to minimise the use of indoor lights, especially in empty buildings. Using dimmers and timers can help to reduce average illumination levels and save energy.

When using indoor lighting, it is also beneficial to use blinds or curtains to block light from escaping outside. This will help to reduce light pollution and improve energy efficiency.

In addition to minimising the use of light, it is important to ensure that light fixtures are properly shielded to prevent light trespass and glare. Light shields, or glare shields, can be attached to the top and/or sides of light fixtures to focus the light downward or inward, reducing unwanted light spread.

By following these measures, individuals can play a significant role in reducing light pollution and its negative impacts on the environment, human health, and our enjoyment of the night sky.

Avoid blue light

Blue light at night is harmful to both humans and wildlife. Research shows that it may contribute to the causation of cancer, diabetes, heart disease, and obesity. Blue light suppresses melatonin, a hormone that influences the body's circadian rhythm, and exposure to blue light at night throws this rhythm off balance.

Blue light emitted by the sun during the daytime has benefits for humans, including increasing attention, reaction times, and mood. However, these benefits become disruptive at night.

Outdoor lighting with strong blue content is likely to worsen sky glow because it has a significantly larger geographic reach than lighting consisting of less blue. Blue-rich white light sources also increase glare and compromise human vision, especially in the aging eye. These lights create potential road safety problems for motorists and pedestrians.

In natural settings, blue light at night has been shown to adversely affect wildlife behaviour and reproduction. This is particularly true in cities, which are often stopover points for migratory species.

To avoid the negative impacts of blue light, here are some recommended actions:

• Use "warm-white" or filtered LEDs (CCT < 3,000 K; S/P ratio < 1.2) to minimize blue light emission. These LEDs have a lower colour temperature and emit a warmer light, reducing the potential harm caused by blue light.
• Choose fully shielded light fixtures that emit no light upward. This prevents light pollution and ensures that light is directed only where it is needed.
• Use dimmers, timers, and motion sensors to reduce average illumination levels and save energy. These controls can lower light intensity and automatically turn lights on and off as needed, reducing unnecessary light exposure.
• Avoid using bluish-white lighting, especially in outdoor settings. Opt for warm-toned lighting options, such as low-pressure sodium (LPS), high-pressure sodium (HPS), or low correlated colour temperature (CCT) LEDs. These alternatives emit less blue light, reducing light pollution and its associated negative impacts.

By following these guidelines, you can help minimize the adverse effects of blue light, contributing to healthier environments for both humans and wildlife.

Install motion sensors

Motion sensor lights are a great way to reduce light pollution. Here are some reasons why installing motion sensors can help:

Energy Efficiency

Motion sensor lights detect human movement and turn on automatically when someone enters the detection area. This eliminates wasted energy from having lights switched on when no one is present. Motion sensor lights are much more energy-efficient than traditional lighting fixtures, saving you money on your electricity bills.

Security

Motion sensor lights can increase security by deterring intruders. Thieves are less likely to target a property if they know their presence will be detected and illuminated by motion-activated lighting.

Convenience

Motion sensor lights provide bright illumination without the need for manual operation. This is especially useful when entering a dark room or area, eliminating the need to fumble around for a light switch.

Cost Savings

In addition to reducing energy costs, motion sensor lights also last longer, resulting in fewer bulb replacements. Motion sensors ensure that lights turn off when no one is in the area, further reducing maintenance costs.

Safety

Motion sensors can enhance safety by alerting you to any movement or activity on your property. This makes it more difficult for someone with malicious intentions to go unnoticed.

Environmental Impact

Light pollution has harmful effects on both the environment and human health. It disrupts the natural lighting patterns, affects the migration of birds, and alters the breeding patterns of nocturnal animals and insects. Motion sensor lights help reduce light pollution by minimising the amount of wasted light emitted when no one is present.

Use LED lights

LED lights are a great way to reduce light pollution. They have a more focused light beam than other types of lights, such as fluorescent or metal halide, which prevents light spillover into unwanted areas. They also tend to be more directional, making it easier to aim the light where it's needed. This can be particularly useful in densely populated areas, where light pollution is a bigger concern.

LED lights have several other advantages over other types of lighting. Firstly, they have a longer lifespan, so you won't need to replace them as often. They also use less energy, which can help reduce energy costs and carbon emissions. Additionally, LED lights have better light quality and superior dimming capabilities, allowing for greater control over the amount of light emitted.

When choosing LED lights, it's important to consider the colour temperature, which is measured in Kelvins (K). For outdoor lighting, warmer colour temperatures with a correlated colour temperature (CCT) of 5000K or lower are recommended. This is because blue light, typically associated with LED lights that have a higher CCT above 5000K, has a larger geographic reach and creates more glare. It also has negative impacts on human health, disrupting sleep patterns and affecting vision.

To further reduce light pollution when using LED lights, consider using shades or covers that force the light downward. This will help to minimise spillover and glare, ensuring that the light is focused only on the intended area. You can also combine LED lights with motion sensors, dimmers, and timers to reduce average illumination levels and save even more energy.

By following these guidelines, you can help minimise light pollution and reduce its negative impacts on the environment, wildlife, and human health, while still enjoying the benefits of efficient and effective lighting.

Frequently asked questions