Greenhouses: Illuminating The Dark Side Of Light Pollution

Light pollution is the human-made alteration of outdoor light levels from those occurring naturally. It has harmful effects on streetlights, satellites, and greenhouses, among other sources. The combination of the commercial greenhouse boom and the increasing use of supplemental light to increase crop yields is causing greenhouses to remain lit long after the sun has set. This is having adverse effects on the environment, humans, and wildlife. The light emitted from greenhouses at night is wasted energy and costs the producers. It can also cause light trespass, impacting the quality of the night sky and nearby areas.

Light pollution from greenhouses can negatively impact human health and psychology

The bright lights from greenhouses at night can also disturb sleep patterns, as they inhibit the production of melatonin, which is crucial for regulating sleep. This disruption can result in insomnia, fatigue, and anxiety in individuals living near these illuminated greenhouses.

Additionally, light pollution from greenhouses can contribute to light trespass, where unwanted light enters neighbouring properties. This can be a nuisance for residents, impacting their quality of life and well-being. Excessive light during the night can also mislead airplanes, increasing the risk of accidents, which further endangers human lives and safety.

While the primary focus of greenhouse lighting is to enhance crop growth, the unintended consequences for humans and wildlife in the surrounding areas are significant. The negative impacts on human health and psychology underscore the importance of addressing light pollution from greenhouses through regulations, technological advancements, and collaborative efforts between growers, citizens, and local governments.

Light pollution can harm wildlife, disrupting foraging and mating

Light pollution is the human-made alteration of outdoor light levels from those occurring naturally. It has harmful effects on wildlife, with animals and plants relying on Earth's daily cycle of light and dark to govern life-sustaining behaviours such as reproduction, nourishment, sleep, and protection from predators.

For example, artificial light negatively affects amphibians, birds, mammals, insects, and plants. Nocturnal animals sleep during the day and are active at night. Light pollution radically alters their nighttime environment by turning night into day. Nocturnal animals are more susceptible to exhaustion and face increased exposure to predators.

Light pollution also affects the mating habits of insects. Insects are drawn to light, creating a fatal attraction. Fireflies, for instance, cease or alter their mating flashes in the presence of artificial light. This can also have a knock-on effect on other species, as declining insect populations negatively impact all species that rely on insects for food or pollination.

Some species of bats use artificially lit areas as easy foraging grounds, which can affect local insect populations. However, other bat species avoid these lit areas, and are then outcompeted by the bats that benefit from the additional food source.

In addition, artificial lights can cause migratory birds to migrate too early or too late, causing them to miss ideal climate conditions for nesting, foraging, and other behaviours.

Light pollution can disorient migratory birds

Light pollution is the human-made alteration of outdoor light levels from those occurring naturally. Sources of light pollution include streetlights, greenhouses, and satellites.

Greenhouses are increasingly becoming dependent on new lighting technologies to increase crop yields. Supplemental electric lighting for greenhouses is essential for extending the growing season in northern climates, but it comes at the cost of environmental light pollution. The light emitted from greenhouses at night is wasted energy and costs the producers.

Artificial light at night can also change birds' perceptions of habitat quality, resulting in the selection or avoidance of illuminated areas. It can influence several aspects of the biology and ecology of birds, including disruption of circadian rhythms and disorientation during flight. Light pollution within geographic ranges was found to be relatively greater during the migration season, for shorter-distance migrants, for species with smaller ranges, and for species in the western hemisphere.

To mitigate the impact of light pollution on migratory birds, properly designed lighting can be beautiful, healthy, and functional. Retractable shades for nighttime growing can help contain offending light and maintain heat within the greenhouse.

Light pollution from greenhouses can negatively impact astronomy

The horticulture industry's increasing dependence on lighting technologies to increase crop yields is a major contributor to light pollution from greenhouses. In particular, the cultivation of crops such as cannabis, which requires a specific lighting regimen, has led to the widespread use of LED grow lights, which can be left on for long periods. This has resulted in a “perpetual false dawn" effect, with greenhouses glowing brightly at night.

The design of greenhouses also contributes to light pollution. While greenhouses are designed to collect sunlight during the day, they can let indoor light escape at night through their windows. This light can be reflected off the plants and ground, causing additional light beyond what the plants need.

To reduce light pollution from greenhouses, measures such as retractable blackout screens, curtains, and window coverings can be used to block light from escaping. Switching to LEDs can also help, as they can emit light focused on a specific area. However, a customized lighting plan is still necessary to prevent light leak.

Light pollution from greenhouses can have negative consequences for astronomy by disrupting the observation of the night sky and making it difficult to see stars and other celestial objects. It can also impact nearby airport operations, as the bright lights can mislead airplanes and increase the possibility of accidents.

Light pollution can be mitigated by using retractable blackout screens and curtains

Light pollution is the human-made alteration of outdoor light levels from those occurring naturally. Sources of light pollution include streetlights, greenhouses, and satellites. Light pollution from greenhouses is a growing concern, especially in regions with explosive growth in the commercial greenhouse industry. The light emitted from greenhouses at night is wasted energy and costs the producers.

Greenhouses use supplemental lighting to increase plant growth and extend the growing season, particularly in northern climates. However, this supplemental lighting can result in light pollution, impacting the environment and neighbouring communities. Light pollution from greenhouses can disorient migratory animals, such as birds, bats, and insects, leading to increased mortality rates. Additionally, it can cause nuisance issues for nearby residents who experience light trespass from the bright glow of greenhouses.

To mitigate light pollution from greenhouses, the use of retractable blackout screens and curtains is highly effective. These screens and curtains are designed to block up to 99% of light from escaping the greenhouse, preventing light trespass and reducing the environmental impact. They are typically installed at gutter height or above the light fixtures, with additional vertical screens along the greenhouse sidewalls to block light from all directions.

The advantages of using retractable blackout screens and curtains go beyond light pollution mitigation. They also offer energy savings by reducing heat loss during winter nights and helping to mitigate humidity build-up. Additionally, they can be used to create optimal lighting schedules for crops, allowing growers to control the photoperiod and influence flowering.

When building new greenhouses, it is essential to consider the potential impact on light pollution and incorporate retractable curtains or screens in the design. This proactive approach is more cost-effective and less disruptive than retrofitting an existing structure. By planning ahead, growers can balance the benefits of supplemental lighting with the need to minimise light pollution, contributing to a more sustainable and environmentally friendly approach to greenhouse horticulture.

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