A cooling design borrowed from church organs cuts noise and power bills.
In a former print works on the edge of the canal basin, a rack of servers runs flat out under a load test, and the loudest sound in the room is the radiator ticking. Normally, a rack doing this much work would roar. This one hums at about the volume of a kitchen fridge, and the company that built it believes the reason lies in a technique borrowed from the pipes of a church organ.
Ardent Acoustics was spun out of Calder University’s engineering department three years ago by two researchers who had been studying how air moves through narrow channels. One of them, Dr Ruth Okonkwo, had spent her doctorate on the physics of organ pipes, trying to understand why some ranks speak cleanly and others hiss. The other, Lukas Brennan, was working on heat transfer in electronics. They met at a departmental seminar and realised they were describing the same problem from opposite ends.
What organ builders knew
A conventional server is cooled by small, fast fans that push air across hot chips and out of the back of the case. The fans are cheap and effective but noisy, and much of the energy they use goes into turbulence – air tumbling over itself rather than carrying heat away. Organ builders have spent centuries shaping pipes and wind chests so that air flows steadily and quietly, at precisely controlled pressures.
Ardent’s design replaces the fans in each server with a shared wind chest at the base of the rack, fed by a single large, slow-turning blower. Air is distributed to each machine through tuned ducts whose length and shape are calculated to suppress the frequencies that make server rooms so tiring to work in. Inside each case, the airflow is guided over the processors by curved baffles modelled on the mouth of a flue pipe.
“An organ is a machine for moving a large amount of air very precisely and making exactly the sound you want. We wanted to move the same amount of air and make no sound at all. It turns out the maths is very similar.”
Okonkwo, now the company’s chief technology officer, said the hardest part was not the acoustics but the reliability. A single blower is a single point of failure, so the production design has two, each able to cool the full rack on its own, and the system switches between them without a pause.
Numbers from the trial
Independent tests carried out at the university over six months found that a fully loaded Ardent rack ran at 41 decibels, compared with around 72 for a standard rack with the same processors. Because the large blower is far more efficient than dozens of small fans, cooling power fell by about 38 per cent. Across the whole rack, including the computers themselves, electricity use was down by roughly 9 per cent – a figure that matters to anyone paying data centre bills.
The first customers are not the giant data centres but smaller operators who keep servers close to where people work: hospitals, universities, broadcasters and engineering firms. The Calder Royal Infirmary has installed two racks in a room next to its radiology department, where the noise of the old equipment had been a long-running complaint from staff.
Scaling up
Ardent employs nineteen people and raised £6.5 million from investors in the spring, including a regional investment fund and a family office in Port Selwyn. It plans to double its workforce next year and is looking for a larger site, ideally somewhere along the canal close to the university. Brennan, the chief executive, said the company had turned down two offers to license the design to large manufacturers. “We want to prove we can build it properly first,” he said. “Then we can talk about who else builds it.”
The organ builders, for their part, are amused. A firm in the hill towns that restores church instruments has been asked to advise on the next generation of ducts.
