Basic fan-only ventilation units can use as little as about 6 watts, for highly efficient models, while many standard units often use around 60 watts or more. In general, electricity usage is related to airflow, measured in cubic feet per minute (cfm) and the fan's energy-efficiency.

Is it bad to leave bathroom fan on?

Experts say bathroom fans can become overheated when clogged by lint and dust, when left on too long or because of simple failure. The heat can ignite the lint, causing the fire. ... Run the fan for only short periods, and never leave it on overnight or while no one is home.

How much does it cost to run a bathroom fan?

Bathroom exhaust fans are not expensive to run when they are working only when necessary. On average it costs $3.5 per year to run a modern correctly sized fan. Heated bath fans are much more expensive to run costing an average of $113 per year.