DTU Nanolab on saving electricity

The air in DTU Nanolab’s cleanroom is replaced with clean air up to 200 times per hour using a comprehensive ventilation system.

Air purification is important, because structures down to 10 nanometres—such as photodiodes and chips with sensor function—are produced in the cleanroom. If the cleanroom air is not kept completely clean, this may damage the highly sensitive micro-electromechanical systems.

But now—in the period from 6 p.m. to 6 a.m.—DTU Nanolab will power down the motors running the ventilators to save electricity at a time of high energy prices. DTU Nanolab’s total energy consumption is around four gigawatt hours a year.

“By reducing the speed of the ventilators and lowering the recirculation by 30 percent in the cleanroom, we can reduce our energy consumption by 68 percent between 6 p.m. and 6 a.m.,” says Head of Operations Leif Steen Johansen.

Same level of safety
Together with Facility Manager Jan Vasland Eriksen, the operations manager ensures that the air quality complies with the ISO 14644 standard for a clean room by continuously measuring the concentration of particles.

“The cost is a potentially lower degree of purity. We don’t compromise on safety,” says Head of Operations Leif Steen Johansen about DTU Nanolab’s latest energy saving initiative.

The 40–50 users who work in the cleanroom on a daily basis are the biggest source of pollution. They include students, researchers, operational staff, and company employees who rent space in DTU Nanolab to use the facilities. They all submit particles such as hair, dandruff, and dust into the air, which may be deposited on the micro and nano devices and destroy their function.

Therefore, DTU Nanolab is reducing the cleaning measures during the evenings and on weekends, when there are fewest people in the cleanroom.


The majority of DTU Nanolab’s 1350 square metres consists of pipes. “We have pipes that connect other pipes on several other lower levels. Every time you have bends on pipes that go from one level to another, you have a loss of pressure. That loss is primarily flow-driven. When we lower the flow—that is the air recirculation—the loss in the pipe system is reduced,” says Jan Vasland Eriksen.
Less pressure loss
DTU Nanolab is located at Ørsteds Plads on DTU Lyngby Campus. A building of 1350 m2 spreading across three floors above ground as well as a basement. What you cannot see from the outside is the ingenious system of ventilation ducts, pipes, cables, and technical installations that make up the entire first and second floors and ensure a constant recirculation of the air in the cleanroom.

When DTU Nanolab lowers air recirculation, it affects the pressure in the ventilation system. The loss of pressure inside the pipes is reduced, and the ventilation system will work less hard to clean the air and therefore consume less power.

In addition to lowering the air circulation, DTU Nanolab also plan to replace the filters that the air passes through before being blown into the cleanroom. They exchange the filters with some that offer lower pressure loss.

“We’ve already done this in parts of the cleanroom, but we would like to extend it to the rest of the cleanroom, which is a bit older,” says Leif Steen Johansen.

Biggest energy saving measures
Together, the two energy efficiency initiatives, lowering the air circulation and replacement of filters, will provide the biggest energy consumption savings at DTU Nanolab, according to the two technicians.

“Overall, with the measures we’re taking, we hope to be able to save up to 10 per cent of our total energy consumption, which is around four gigawatt hours a year,” explains Jan Vasland Eriksen.

At current electricity prices—for example DKK 4 per kWh—this equals savings of DKK 1.6 million.

In connection with a minor refurbishment and programming, the ventilation units have now been connected to Campus Services CTS system, which is a building control system. This enables Campus Service to control the main ventilators and Fan Filter Units (FFU) centrally. This also means that DTU Nanolab does not have to reduce the flow manually in the evenings and on weekends.