Colour Temperature
What is Colour Temperature?
Colour temperature, measured in Kelvins (K), is a way of measuring the appearance or colour of a light source. The lower the colour temperature, the warmer and more yellow or orange the light appears, while higher values describe cooler, bluer light.
- 1800K – Candlelight (soft, warm glow – soft ambient lighting for alfresco dining)
- 2200K – Warm white (insect friendly subtle outdoor lighting for paths and amenity areas)
- 2700K – Extra warm white (similar to incandescent bulbs – considered the maximum wildlife friendly colour temperature)
- 3000K – Warm white (soft white, commonly used residential streets, parks and pathways)
- 4000K – Cool white (neutral white – industry standard for street lighting)
- 5000K – Cool white (clear with high contrast – high traffic, high security areas, sports lighting)
- 6500K – Very cool white (cool, bluish light used for task lighting)
- 8000K – 12000K – Blue sky (very cool, blue light resembling clear skies – generally not used outdoors)
Why does colour temperature matter?
Colour temperatures affect the ambiance or mood of a space, and different colour temperatures can have physiological effects on humans and animals. Warmer colour temperature lights are considered less light-polluting than colder blue lights. Warm red light is also less disruptive to the behaviour and habitats of animals, and less disruptive to the circadian rhythms of humans.
What is the best colour temperature for wildlife-friendly lighting?
Cooler light temperatures (blue white light) disrupt the nocturnal activity of wildlife, so warmer colours (ideally 2700K or lower) can help minimize harm and light pollution.
Why are non-white lights not described in Kelvins?
Colour temperatures of non-white lights are typically not measured in Kelvins because the Kelvin rating system specifically describes how warm or cool a white light source appears.
Dark Sky & Wildlife-Friendly Lighting
What is Dark Sky friendly?
DarkSky friendly lighting follows these principles:
- Useful – Only use light when and where it is needed.
- Targeted – Direct light to specific areas, avoiding unnecessary spill.
- Low Level – Ensure light is no brighter than necessary for its purpose.
- Controlled – Use lighting only when required (e.g., with timers or sensors).
- Warm – Opt for warmer colour temperatures to reduce harsh blue light at night.
Lighting systems can get DarkSky certified, indicating that the product helps protect the natural night environment by limiting light pollution.
To be DarkSky friendly, lighting systems often use controls like light shields, dimmers and motion sensors to minimize glare, light spill, and excessive brightness.
Lighting Control Systems
What is Zhaga?
Zhaga refers to a set of standards that ensure interoperability and future proofing of lighting components. Zhaga compliant lighting uses standarised components, making them easy to upgrade, maintain, and interchange.
These systems are also compatible with new technologies, making them smart city ready.
What is DALI?
Digital Addressable Lighting Interface (DALI) is a lighting control system designed for precise and dynamic control over the components of a lighting system. It is an open protocol, meaning any lighting manufacturer can use it. Luminaires from multiple manufacturers can be controlled simultaneously if they are compatible with DALI lighting controls.
DALI comes with a wide range of options and controls, like dimming, colour changes and timers.
What is 1-10V dimming?
1-10V is a dimming technology that controls light intensity by regulating the amount of DC voltage a light fixture receives. At 1V, the light emits 10% of its maximum brightness, scaling up to 100% at 10V.
Luminous Output & Measurement
What are Lumens?
Lumens (lm) are a unit of measurement used to quantify the total amount of visible light emitted by a source.
The required lumen output for a lighting system depends on several factors, including:
- Mounting Height
Lights mounted higher need a greater lumen output to provide sufficient illumination on the ground.
- Environment
The type of area being lit, whether it’s a residential street, a public park, or a motorway. Factors like visibility, safety, and energy efficiency play a key role in deciding how many lumens are needed.
Some examples of typical lumen values for outdoor lights in different environments:
- Public walkways and parks: 800lm – 2,500lm
- Residential streets: 3,000lm – 7,000lm
- Building facade lighting: 2,000lm – 10,000lm
- Motorways: 15,000lm – 30,000lm
- Large sport stadiums: 50,000lm – 100,000lm
What is the difference between Lumens and Lux?
While lumens measure the total light output of a source, lux measures the intensity of that light as it illuminates a surface, expressed as lumens per square meter.
For example:
- Floodlights used in television broadcasting for professional sports typically have lux values ranging from 1000 to 2000, with a lumen output between 50,000 and 100,000.
- Residential street lights with low traffic generally have a lux value between 10 and 30, with a lumen output ranging from 3,000 to 7,000.
What is Luminous Flux?
Luminous flux (also known as lumen flux) describes the rate at which light (in lumens) is emitted by a light source over time. It provides a specific measurement of how much light is emitted at a given moment.
Light Quality & Performance
What is CRI (Color Rendering Index) in outdoor lighting?
Colour Rendering Index (CRI) is a measurement of how accurately colours appear when illuminated by artificial light compared to natural daylight. CRI is expressed on a scale from 0 to 100, with a high CRI indicating more accurate colour representation.
LEDs used for outdoor public lighting typically don’t have a CRI of 100, as it requires less energy-efficient, more expensive LEDs. As a result, most outdoor LED lighting has a CRI between 70-80, balancing colour accuracy with cost-effectiveness and energy efficiency. In contrast, older HPS (High Pressure Sodium) streetlights have a CRI in the 20 to 30 range.
What is the difference between RGB and RGBW?
RGBW (Red Green Blue White) light contains a white LED chip as well as the traditional red green and blue ones, giving lighting systems more colour options as well as the ability to create clearer white light, with a high brightness and colour accuracy or CRI.
Types of Outdoor Lighting
What is the difference between “flood” and “spot” outdoor LED lighting?
The difference between flood and spotlights lies in the beam angle and the area they illuminate.
- Floodlights produce a wide beam that illuminates a large area.
- Spotlights cast a narrow beam that concentrates illumination on a specific object or area.
Energy Efficiency & Sustainability
What is “daylight harvesting” in outdoor lighting?
Daylight harvesting is an energy-saving technique that adjusts artificial lighting based on the amount of natural light available. During daylight hours, lights typically remain at a low level or off, gradually brightening as natural light decreases.
Protection & Durability
What is a surge protector?
A surge protector is a device that protects electrical systems from surges of high voltage electricity. It works by limiting voltage and diverting high volumes of electrical current away from sensitive equipment.
What is the “L90 lifetime” of an outdoor LED light?
L90 lifetime is a measure of an LED light’s lifespan, indicating the point at which the light output has deteriorated to 90% of its original brightness.
What does IP rating mean for outdoor LED lights?
IP (Ingress Protection) is a two-digit rating system indicating an object’s resistance to dust and moisture.
- The first digit measures protection against solids (e.g., dust) on a scale of 0 to 6.
- The second digit measures protection against liquids (e.g., water) on a scale of 0 to 8, with 8 signifying full waterproof protection.
Common IP ratings include:
- IP65: Dust-tight and protected against water jets.
- IP66: Dust-tight and protected against powerful water jets, including high-pressure water streams.
- IP67: Dust-tight and protected against immersion in water up to 1 meter depth for 30 minutes.
- IP68: Fully protected against dust and can withstand continuous immersion in water, typically beyond 1 meter depth.
Modern outdoor lighting systems typically have an IP rating ranging from IP65 to IP68. Recessed ground lighting and lighting in areas with harsh weather conditions, where exposure to water is expected, generally have IP ratings of IP67 or IP68.
What does IK rating mean?
IK rating (Impact Protection) describes how well an object, such as a luminaire, can resist impact, on a scale from 0 to 10. Higher numbers indicate better protection from things like vandalism or fall damage.
Common IK ratings include:
- IK06: Protection against 1 joules of impact. Equivalent to the impact of 0.25kg mass dropped from 400mm above the impacted surface.
- IK07: Protection against 2 joules of impact. Equivalent to the impact of a 0.5 kg mass dropped from 400 mm above the impacted surface.
- IK08: Protection against 5 joules of impact. Equivalent to the impact of 3.75kg mass being dropped from 300mm above the impacted surface.
- IK09: Protection against 10 joules of impact. Equivalent to the impact of a 2.5 kg mass dropped from 400 mm above the impacted surface.
- IK10: Protection against 20 joules of impact. Equivalent to impact of 5kg mass dropped from 400mm above impacted surface.
Outdoor lighting systems typically have IK ratings ranging from IK07 to IK10. Lights in busy areas with potential for vandalism or accidental damage such as streets and car parks generally have higher ratings.