Two Japanese companies have sparked a debate on running ventilation fans for 24 hours in bathhouses. The topic is triggering fresh conversations about power consumption, safety, and interior design in Japan. Advocates argue that continuous ventilation prevents the growth of mold and bacteria, while opponents claim it's an energy-wasting practice yielding little benefit.

The practice of running ventilation fans 24/7 originated as a part of Japanese lifestyle to counter dampness and hygiene issues in their bathhouses, an essential component in Japanese homes. While energy conservation is a valued principle in Japanese society, it has created a tension between ensuring a comfortable living environment and reducing energy consumption.

In the US and EU, the usage of ventilation systems is generally dependent on the specific needs of the building and its inhabitants. There is no widespread culture of running bathroom fans continuously, though the debate about energy efficiency vs. comfort is a common theme globally.