I’m not sure there is a definitive answer, at least an official one. I’d compare it to asking how long is a piece of string is, without having a tape measure to hand. Raising energy costs throughout, various modes of running, length of use and the size of the room that being heated or purifier.  

Thankfully, compared to other months, I’ve tracked a reduction in my house bill by using my purifiers AUTO mode. I’d suggest this is something you look into. Even dropping the temperature by a degree or two can make all the difference.

Hi. I’ve found it to be incredibly difficult to get an accurate cost for a base model fan, let along one for a purifier. It’s dependant on factors such as, airflow setting (heating/purifying), fan speed (0-10), operation space (Room size), energy cost (price per kilowatt) and wattage. Thankfully I found an example online which i was happy to accept.  

Most HEPA air purifiers consume around 50-100 watts per hour. With 12 hours of daily operation, the electricity will be around £3-5 a month or £36-60 annually. Where you have the unit in use for 24 hours operation, you just multiply the numbers by 2.

@Charlie Great question! It can be difficult to give a completely accurate response. It depends on how often you use the machine, airflow and temperature settings, current in-home temperature, and cost of electric within your municipality. All those will go into the overall factor, for the cost to run your unit.