Sports fields used to be located outside the city, but as the cities have grown, many sports fields are now located in the middle of housing areas close to people’s gardens. And doing sports has become very popular. Each year, 30 artificial turf pitches pop up around the country, and the clubs want to play until late in the evening.

Consequently, the problem with neighbours complaining about the strong light has grown steadily bigger in recent years.

Some municipalities have tried it implementing rules for when the stadium lights are allowed to be on, and even with rules for the level of brightness, neighbours are still bothered by the lights, and it has been difficult to find a solution that fits all.

Senior Researcher at DTU Fotonik Henrik Chresten Pedersen therefore didn’t hesitate when he was contacted by the Danish company NorthLED who wanted his help finding a solution.

New LED technology invention

Henrik works with light research, and he managed to invent an entirely new type of lens which ensures that the light only touches the field and also consumes less power.

“It hasn’t previously been possible to use the energy-saving LED technology for sports fields because the LED lights couldn’t be made to light only the field while mounted on tall masts. Fortunately, we’ve now solved this problem so the lens now not only reduces light pollution but also power consumption,” Henrik explains.

The lens is made from a piece of acrylic, which is placed in front of an LED light bulb. The acrylic piece ensures that the light is focused on the field. In fact, the new lens is so effective that it reduces light pollution with an impressive 90 per cent and energy consumption by 48 per cent.

The new LED light bulbs also last much longer.

“The LED light bulbs last, on average, 50,000 hours, whereas the old halogen light bulbs only lasted approx. 1000-3000 hours. It’s a great advantage that the light bulbs last as long as they do, because its quite difficult to change a light bulb on a 18 metre mast,” says Henrik.

Lamps tested since autumn

In order for the lens to be used for sports fields, it has been built into the panels of specially designed lamps, which can be mounted on masts. NorthLED has been responsible for this part of the job.

Since this autumn, the new lens has been tested in Roskilde, and Himmelev-Veddelev Boldklub (Himmelev-Veddelev football club) and the club’s neighbours in the Roskilde municipality were thus among the first to benefit from the new invention.

“We are very excited about our new lights. They’re much more clear. Previously the lights would only cover parts of the field, but now the whole field is properly lighted. It’s a notable improvement from the old lighting, which consisted of halogen light bulbs. And the light no longer bothers the neighbours,” says Chairman of the Himmelev-Veddelev Boldklub Carsten Reinholdt.

He has not heard from disgruntled neighbours since the new lights were installed in autumn. And as an added bonus, he can now control the lights from an app on his mobile phone, so he is very pleased.

Himmelev-Veddelev Boldklub has kept the old halogen stadium lights, however. The new field, with its new lights, now aims to show other municipalities, installers and engineers how big the difference is between the old lights and the new. The Aarhus, Rudersdal and Silkeborg municipalities are all considering having the new lights installed.

The project and testing of the lights were completed in January 2018, and Henrik Chresten Pedersen and the NorthLED company have filed for a joint patent for the lens.

Source: DTU