40 percent energy saving
The study at Kungsholmen aimed to find out how smart lighting control system can be used to reduce energy consumption in urban environments - without affecting the safety and visual comfort. The results showed it was possible to reduce energy consumption by 40 percent through the installation of sophisticated lighting control systems.
Fagerhult in cooperation
The City of Stockholm paid for the technology infrastructure. The project was part-financed by the Swedish Energy Agency through Sust ( Sustainable Innovation ) who has coordinated the project. Fagerhult and Tritech has developed the luminaires and control systems and contributed with their lighting and technical expertise.
A clear favourite
Five different lighting scenarios were tested and evaluated in the autumn of 2012. The solution that is currently in place was a clear favorite, according to a study done by Harita Undurty Surya and Efi Stragali (supervisor) at the Royal Technical University's ( KTH ) lighting laboratory.
A total of 750 meters and 34 LED luminaires have been placed along a bicycle and walking path in the centre of Stockholm. Each fixture has sensors that detect when a pedestrian or cyclist is approaching. The luminaire is individually controlled, but they still interact with each other. If no movement is detected the lighting is reduced to half the brightness (left picture), but once someone approaches the space, the lights automatically turn up to the full level in groups of seven (right picture).
Four luminaires provide light for approximate 60 meters in front of the pedestrian or cyclist, while three fixtures light behind them. After one minute the light level is reduced to the subdued level as the road user leaves the area.
In Stockholm's parks and public streets there are around 50,000 points of light that consumes an estimated 14 million kWh per year. " The savings potential is enormous. The technique is very interesting for the future," says Anders Hedlund, lighting engineer at Trafikkontoret, City of Stockholm.
Undurty Surya Harita, B.Arch, M.Sc in Architectural Lighting Design
Harita is an architect from India who after graduating in architecture decided to immerse herself further in the subject lighting design. This led her to the master's program at KTH , the Royal Institute of Technology in Stockholm, Sweden.
"Light and People" is the topic that interests her most, and according to her, is the most important element in lighting design.