Blog | Colour temperature – warm white versus cool white outdoor lighting
Published 10:00am August 15 2024
When planning outdoor lighting, the importance of colour temperature extends beyond aesthetics and functionality – it also has significant implications for health, wildlife, and ecosystems. Choosing the right colour temperature can influence human circadian rhythms and play a vital role in protecting local wildlife by minimising light pollution and its disruptive effects on nocturnal animals. In this blog, we will delve into the benefits of selecting appropriate colour temperatures for outdoor lighting, emphasising how thoughtful choices can enhance human health and preserve the natural balance of surrounding ecosystems.
What is colour temperature and how is it measured?
Colour temperature describes the hue of a particular type of light source and is measured in Kelvins (K).
Cool white light typically has a colour temperature between 3500K and 5000K or higher. This light appears more blue or white, like natural daylight or fluorescent lighting.
On the other end of the spectrum, warm white light has a colour temperature between 2700K and 3000K. This light appears more yellow or orange, like traditional incandescent bulbs or the setting sun.
The technical reason for this variation is to do with spectral composition and the distribution of different wavelengths of light emitted by the light source. Warm white light has a higher proportion of longer wavelengths (yellow, orange, and red) and a lower proportion of shorter wavelengths (blue). This results in a softer, warmer glow that is often perceived as more relaxing and less harsh.
Cool white light on the other hand has a higher proportion of shorter wavelengths (blue) and a balanced distribution of medium and longer wavelengths (green, yellow, and red). This results in a brighter, more intense light that can appear cooler and more energising.
Why is warm white lighting considered beneficial?
Warm white lighting is considered beneficial to both humans and animals due to several health, comfort, and environmental reasons.
The benefits of warm white lighting on human health
For humans, exposure to blue light, particularly during the evening and at night, can suppress the production of melatonin. This suppression delays the onset of sleep, reduces sleep quality, and can lead to shorter sleep duration. Additionally, warm white lighting is gentler on our eyes, causing less eye strain than blue light. Warm white lighting also creates a cosy and inviting atmosphere making it ideal for residential settings.
The benefits of warm white lighting on animal health
For animals, warm white lighting is less disruptive to nocturnal behaviour and migration patterns. Nocturnal animals, which are sensitive to artificial light, experience fewer disruptions to their natural behaviours under warm white lighting. Cooler white lights can interfere with the migration patterns of birds and other species, while warm white lighting is less likely to attract and disorient migrating animals. Furthermore, warm white lighting minimises the impact on ecosystems by attracting fewer insects compared to cool white and blue-rich light sources. This leads to less ecological disturbance.
Ever wondered why insects are attracted to artificial lighting? Check out our blog Do Solar Lights Attract Bugs? >
Why do ecologists recommend warm white outdoor lighting?
When it comes to outdoor lighting, ecologists often recommend warm white lighting for several key reasons, focusing on the protection of wildlife, preservation of ecosystems, and reduction of environmental impact.
Warm white lighting emits less blue light, which is less disruptive to nocturnal animals compared to cool white or blue-rich light sources. Many animals, especially nocturnal ones, are highly sensitive to artificial lighting. Cool white lights can interfere with their natural behaviours, such as foraging, mating, and predator-prey interactions. By using warm white lights, the disruption to these behaviours is minimised, helping maintain the balance of local ecosystems.
Cool white and blue-rich lights attract more insects than warm white lights. This can lead to an imbalance in local insect populations and disrupt food chains, as insects are a primary food source for many other animals. By using warm white lighting, the attraction of insects is reduced, thereby minimising ecological disturbances.
Artificial lighting can have cascading effects on entire ecosystems. For instance, disrupting the behaviour of one species can affect the species that depend on it. By minimising the impact of outdoor lighting with warm white LEDs, ecologists aim to preserve the intricate balance of these ecosystems, ensuring the survival and health of various species.
Why is warm white outdoor lighting better for bats?
In the UK, many bat species are protected by law due to their declining populations and crucial role in ecosystems as pollinators and insect controllers. Using warm white lighting supports conservation efforts by creating a more bat-friendly environment, reducing the negative impacts of artificial lighting on these vulnerable species.
Many bat species in the UK feed on insects that are active at night. Cool white and blue-rich lights attract more insects, which can create an unnatural concentration of prey around these light sources. This can alter the natural foraging behaviour of bats, leading them to rely heavily on these artificially lit areas, which might not be sustainable in the long term. Warm white lights attract fewer insects, thereby helping to preserve a more natural distribution of prey.
Learn more on Bat Hibernation & The Impact of Outdoor Lighting on Bats >
What colour temperature is recommended to protect bats?
To protect bats, it is recommended to use outdoor lighting with a colour temperature of 2700K or lower. Lighting in this range is considered warmer and emits less blue light, which is less disruptive to bats and other nocturnal wildlife. The lower blue light intensity helps preserve the natural behaviour and habitat of bats, reducing the negative impacts of artificial lighting on their activities and overall well-being.
Warm white outdoor solar lighting from Solareye
Here at Solareye, we believe there is a balance to be struck between providing safe and inviting public spaces and preserving natural ecosystems. As we’ve seen throughout this blog, warm white outdoor lighting has many benefits to human populations, animals and ecosystems, which is why Solareye80 ground light and Solareye Bollard Light are both available in warm white. To find out more about our warm white solar lighting, get in touch with our friendly team today.
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