A new age of outdoor lighting

"Light ramps" may someday replace older street lighting.

Jan Ejhed, Sweden's only professor of lighting design and director of Ljuslaboratoriet (the Lighting Laboratory) at KTH, wants to see some changes in street lighting.

"Street lights are far too often adapted to vehicle traffic. We need to change that way of thinking and illuminate sidewalks and the surrounding environment instead," Ejhed says.

For nearly 30 years he has conducted research on the application of light in built public environments, and how light in urban areas affects people.

At the seminar Outdoor Lighting '11 at Stockholm’s Army Museum on August 29 and 30, Jan Ejhed showed how lighting can be used to create safe urban environments.

"One of the most important things I want to convey is that society must start to re-evaluate street lighting. Illuminate the pavement and bike paths instead of having lights hung in the middle of the road," says Ejhed.

"Motorists will get a better view of the unprotected road users on the side of the road, and that will help avoid accidents. The headlights on modern cars are strong enough to sufficiently illuminate the roadway itself."

Ejhed says we’re at the beginning of a transformational change in the way public areas are lighted.

"For example, street lighting is usually upgraded with metal halogen lamps, which are mounted on the old lampposts with the fixture at the very top. But in the future it may prove to be more efficient with a light ramp, which lines up LED lights on panels about 50 cm long," he says.

Sodium-vapour lamps are also still in use. These produce a lot of light per watt, but they give off a yellowish, poor quality light. Metal halogen lamps are gaining in market share, but Ejhed believes LED lighting will eventually dominate.

"LED lighting, which is known to be the most environmentally friendly option in the production process, also provides highly flexible and energy-efficient lighting. Unfortunately, the lamps are still too expensive and the technology too immature to be fully utilised. This change will take time."