Built around a natural geothermal spring, the baths receive nearly a million visitors a year who come to see how Roman engineers used the spring to provide bathing facilities for the temple and spa complex that occupied the site around 2,000 years ago.

The remains are now owned by Bath & North East Somerset Council, which has recently re-displayed the entire site. One improvement is a glass walkway, around four metres long by a metre wide. This allows people to walk across the main drain that carries overflow water from the baths to the River Avon. The problem was that condensation on the glass from the warm water obscured visitors' views of the drain.

To address the problem, ABB Drives Alliance member APDS installed a 0.37 kW ABB machinery drive controlling a fan.

The system ran at full speed, 50Hz, throughout the night on cheap rate electricity, clearing the condensation from the glass walkway panels in time for the museum opening at 9:00 or 9.30am.

It then ran at 33Hz throughout visitor hours to keep condensation away and to keep the noise produced by the fan to an acceptable level.

The fan and drive were in place for six months to prove the concept. The trial period proved that the method worked and two more fans driven by ABB machinery drives have now been installed.