How to Choose the Color Temperature of Street Lights?

① Residential Areas and Leisure Scenarios (Prioritize Warm Yellow Light/Low Warm White Light)

Scenario characteristics: Focus on "comfort, tranquility, and not affecting residents' rest". The lighting intensity does not need to be too high to avoid light pollution.

Recommended color temperature: 2700K-3500K (2700K warm yellow light is the softest, suitable for community walkways and inter-building street lights; 3000K-3500K warm white light can be used in community squares to balance activity needs and comfort).

Taboo: Avoid cool white light above 4000K, which can make the environment appear cold, and the strong light at night may affect residents' sleep (glare interference in light pollution).

② Slow Traffic Scenarios (Prioritize Warm White Light)

Scenario characteristics: Sidewalks, non-motorized vehicle lanes, campus roads, etc., require "clearly identifying pedestrians and obstacles while reducing visual fatigue".

Recommended color temperature: 3500K-4000K (Warm white light has good color rendering, can accurately restore details such as pedestrians' clothing and road potholes, avoiding "color distortion" under warm yellow light, and is softer than cool white light, suitable for long-term walking/cycling).

③ Fast Traffic Scenarios (Prioritize Cool White Light)

Scenario characteristics: Arterial roads, secondary trunk roads, highways, bridges, etc. The core demand is "high brightness and high recognition to help drivers quickly capture road conditions (such as pedestrians, road signs, and vehicles)".

Recommended color temperature: 4000K-5000K (Cool white light has high light efficiency, higher road illumination under the same power, and can clearly restore the color of road signs (such as red for prohibition and green for instructions), reducing drivers' visual delay).

Taboo: Avoid warm yellow light below 3000K. Under low color temperature, the road brightness is insufficient, and it is easy to be confused with the red color of "brake lights" and "warning lights", increasing potential safety hazards.

④ Special Scenarios (Customized Selection)

Historical districts/ancient buildings: Need to balance lighting and "protecting building colors", recommend 2700K-3000K warm yellow light (low color temperature avoids strong light from damaging the paint and murals of ancient buildings, and is in line with the historical atmosphere).

Tunnels/underground passages: The entrance/exit requires "transitional color temperature" (such as 5000K cold white light at the entrance to connect with outdoor strong light, and 4000K cool white light inside to avoid visual blind spots caused by "sudden brightness changes"); color temperature below 3000K is prohibited inside to prevent insufficient brightness.

Rainy/foggy areas: Prioritize 2700K-3000K warm yellow light (warm yellow light has a longer wavelength and strong penetration. In foggy weather, it can reduce "veiling reflection" and make the road clearer; cool white light is easy to scatter in fog, which instead reduces visibility).

The adaptability of human eyes to color temperature directly affects fatigue. Pay attention to two key points:

Avoid high-color-temperature blue light pollution: Cold white light above 5000K contains a lot of short-wave blue light. Long-term exposure at night will inhibit the secretion of "melatonin" (affecting sleep), and it is more irritating to the eyes of the elderly and children, so it is only used for a short time in special scenarios.

Avoid insufficient brightness at low color temperatures: If the power of warm yellow light below 3000K is insufficient, it will cause the road to be "dark". Pedestrians/drivers need to struggle to distinguish road conditions, which instead increases fatigue. It is necessary to match sufficient "illumination" (such as ≥5lux for residential street lights and ≥20lux for arterial roads).

Street lights with different color temperatures have different energy-saving properties when paired with light sources (such as LED and high-pressure sodium lamps), so it is necessary to select them in combination with the light source type:

LED street lights: The mainstream choice, with a wide adjustable color temperature range (2700K-5000K). Moreover, high-color-temperature (4000K-5000K) LEDs have higher light efficiency (such as 4000K LEDs have a light efficiency of about 130lm/W, and 2700K about 110lm/W), which is more energy-saving for long-term use.

High-pressure sodium lamps: Traditional light sources with a fixed color temperature (2000K-2500K warm yellow light), low light efficiency (about 80lm/W), and high energy consumption. They are gradually replaced by LEDs and are only suitable for the renovation of old communities with limited budgets (note: sodium lamps have poor color rendering, which is easy to cause color distortion).

To pursue "energy saving + comfort", prioritize 3500K-4000K LED street lights, which balance light efficiency and visual experience.