Many factors are involved such as room size, room construction materials, what rate your electric company charges, etc.
An average residential traditional sauna is approx. 6' x 6' x 7' (4 people) and requires a 220/240v 6KW heater. If the cost per kilowatt hour is 10 cents, the heating cost per hour is 60 cents.
An infrared average size is 34" x 45" x 66" (1-2 persons) with a power source of 120V and has an output of 1.6KW. If the cost per kilowatt hour is 10 cents, then the heating cost per hours is 16 cents.
Thanks for the response. I am surprised at the cost between the two, that is quite a difference. I don't think we would ever eliminate our traditional sauna since our clients love it, but the lower operating costs sure make the infrared more attractive as an additional offering.