Mr Tsujimoto said: “Cooling and fresh air machines must be silent and must consume less energy. We must be able to reduce the big energy consumption of cooling machines in Japan and reduce the noise of these machines.

“The requirements changed during the past 100 years. In the beginning, the focus was on the life period, later on the ventilation system performance. The energy consumption has been important for roughly 20 years. Furthermore, people have evaluated noise as pollution of the environment or as noise disturbance for the past few years.”

Ziehl-Abegg is a leader in bionic fan design, with its engineers having transferred characteristics from the owl, the eagle, the humpback whale, and even trees into fan designs, always with the aim to reduce noise and to optimise the fans’ aerodynamics to reduce energy consumption.

Mr Tsujimoto concluded: “There are two possibilities: the planning of new buildings and the refurbishment of existing buildings. The ventilation system of old buildings is often too noisy and consumes too much energy. If you refurbish with energy saving fans, it is not necessary to modify the tube system.”