© Ralf Kreuels

Here come the sound guys

The team of engineering consultants from Teensma makes sure things are quiet wherever noise would disturb people, including residential areas with people who surf the Internet at high speed using fiber-optic connections.


Given that Peter van der Velde actually has nothing to do with ventilation and air conditioning, he has put a lot of thought into them in the last few years. As the managing director of the Dutch engineering firm Teensma, he and his staff of six usually work to keep people from being bothered by noise. Teensma insulates big industrial plants, improves acoustics in classrooms, or makes sure that electrical installations in residential areas don’t disturb anybody with their humming.

An example is the distributor stations for fiber-optic cables. They bring fast Internet access into the living room from the higher-level networks. The stations naturally have to be as close as possible to the users, but they shouldn’t make any noise. And this is where the air needed for cooling comes into play, the air that van der Velde has thought about so much lately.

Cooling with outside air

“Normal air conditioners are usually used to cool distributor stations in residential areas, but they’re often relatively loud and bother the neighbors. When we were tasked with making such a station quieter, first we developed insulation for the existing installation.

Small team, big job: The staff at Teensma make distributor stations for fast Internet in residential areas quieter. ( Photo | Ralf Kreuels)

Small team, big job: The staff at Teensma make distributor stations for fast Internet in residential areas quieter. ( Photo | Ralf Kreuels)

The result was a system that was quieter, but expensive to operate and so complex that only specially qualified technicians could work on it. Since we as engineers prefer to think things through from the beginning rather than from the end, we set ourselves the goal of significantly reducing noise at the source while also making the system design much simpler.”

So the team began work on a ventilation system that would cool the equipment in the distributor station using only outside air. This method had not yet been implemented successfully in such distributor stations and was viewed by many as insufficiently reliable. Van der Velde and his team worked mainly on the control system and the right filters for the ventilation system; moisture and particles must not be allowed to harm the sensitive equipment.

The engineers from Teensma were also very careful in their choice of fans, as van der Velde recalls: “From the beginning, we had ebm-papst and a competitor in mind for the required EC fans. We ordered products from both companies and tested them precisely in various installation scenarios. The results were clearly in favor of ebm-papst. On average, its fans were four to five decibels quieter than the ones from its competitor. And the information in the data sheets about air flow, pressure and noise level matched reality exactly. That may sound kind of trivial, but it’s definitely not something you can take for granted with a lot of manufacturers. Sometimes they’re a bit more optimistic with their values.”

80 percent less energy

The first prototype with ebm-papst fans confirmed the engineers’ assumption that fresh-air cooling with EC fans would result in a bundle of benefits. Just a few steps away from the distributor station, people no longer perceive its noise as disturbing. Due to their higher efficiency, the fans also give off less heat into the station’s interior and reduce its energy consumption drastically. The distributor station with fresh-air cooling uses 80 percent less energy than its predecessor with a conventional air conditioner.

The data from ebm-papst are exact. That sounds trivial, but it’s not something you can take for granted.

Peter van der Velde — Managing Director of Teensma

Beyond that, van der Velde can cite other advantages: “Ventilating with fresh air is very simple. Maintenance staff need no special qualifications. We can tell them everything they need to know in just a few hours. The system has fewer components, so it’s less likely to have malfunctions. Our product has been on the market for three years and there were only two malfunctions in that time, and they had nothing to do the fans. Another plus is controllability. They can be adjusted to the exact output needed for the season and the temperature.”

Faster streaming

Teensma has sold over 300 distributor stations to the Dutch fiber-optic network operator Reggefiber, and the German operator Deutsche Glasfaser has bought over 100 stations. The product from the small Dutch engineering firm does its part in many areas to give people fast streaming, games and shopping without having a humming box in front of their houses. Van der Velde is optimistic about the future, saying “I see lots of potential for our distributor stations in the coming years. Fast Internet is often taken for granted in big cities, but there’s still a lot to be done in rural areas. With our quiet and simple systems, we make it easier to expand the networks, especially in such regions.”

How the stations are cooled

Teensma packs all of a station’s equipment into a structure made of concrete, which makes climate control easier due to its delayed heat absorption and dissipation. Teensma sells stations in two sizes. Depending on their purpose, they can be as large as a garage or a small shed. The smaller units can supply several hundred households with a fiber-optic connection; the larger ones can supply over 2,000.

To cool the electronics in a station, RadiCal EC fans suck in cool outside air and convey it into the station under the floor. From there it flows into the room through a fine grill and cools the electronics as it flows by. The resulting warm air then flows beneath the ceiling and back to the outside. Since the EC fans can be smoothly adjusted, the temperature in the distributor stations remains below the standard operating temperature of the electronics regardless of the season and the ambient temperature.

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