This is an addendum to Trumpkin’s Notes On Building A Sauna which should be read for more information.
IR vs Sauna
First, IR Booths / IR Cabins are not sauna. A sauna is a room heated by stones upon which water is thrown to create steam and control the humidity. This steam, along with pure fresh air, and even convective heat evenly around your entire body result in the löyly (good sauna environment) that sauna is known for.
IR booths do not have stones nor do you throw water on imaginary stones to create steam. IR booths do not have convective heat nor is the heat even around bathers bodies. IR booths do not have the capability of löyly.
Sauna and IR booths are however somewhat similar and, despite what some say, one is not necessarily better than the other. In both you are in an enclosed space and some part of your body is being heated. Both frequently have walls, ceilings and benches of wood. That’s about it for similarities.
The experience between IR and sauna is quite different, how our bodies react is different and the health benefits are different.
Heat – In a sauna you are heated by convection and conduction while in an IR cabin you are heated by radiation. Good sauna builders try to eliminate radiant heat as best they can.
Löyly – In a sauna you throw water on the stones to temporarily (except in American saunas with poor ventilation) increase the humidity and experience löyly. Repeated every few minutes provides an experience of humid/dry/humid/dry/humid/dry that is very comforting and healthy (similar to hot/cold/hot/cold/hot/cold being both comforting and likely the primary health benefit). Löyly is a core element of Finnish sauna and something that you don’t have in an IR cabin.
Dry vs Humid – An IR cabin is purely a very dry heat. Sauna is naturally dry but throwing water on the stones creates a more humid environment, though not nearly as humid as a Turkish Bath or Steam Room.
Full Body vs Skin Deep – In a sauna you are breathing much warmer air so your respiratory system is experiencing something similar to the rest of your body – you’re more even inside and outside. In an IR cabin your body is experiencing much greater warmth than your respiratory system.
Evenness – Your body experiences more even warmth all around in sauna (again, Finnish sauna, as many American saunas are extremely uneven) vs IR that is much less even and often only on 3 sides. Many of the health benefits of sauna such as improved immunity and cardiovascular system as well as the enjoyment are from the cycling of hot/cold/hot/cold/hot/cold. This is not as possible nor as comfortable with IR because with IR the heat is only skin deep.
Health – The differences in health benefits are unknown. While there is good information on sauna, there is very little on IR cabins. Some info on NIR and FIR treatments is appropriated for IR cabins but it’s not necessarily the same so be cautious. My guess is a bit of overlap of a few benefits and then a few that are exclusive to one or the other.
Space – An IR booth is by necessity quite small as you need to be near the IR panels to get any benefit. Saunas are generally much larger and can be as large as you want.
Social vs Solitary – Sauna is one or many people and is very often as much a social experience as anything. IR cabins are, by necessity, usually solitary.
IR Cabin vs Finnish Sauna vs American Sauna
There is a much greater difference between a Finnish sauna vs IR than a typical American sauna vs IR. An American sauna with poor ventilation, low ceiling, low benches and seating too close to the heater is, from an enjoyment standpoint, not much different than IR. A proper Finnish Sauna is, for me anyway, much more enjoyable.
Some vendors sell combination IR and Sauna units. From an IR standpoint these likely work just as well as any IR Booth/Cabin. The sauna experience is quite compromised though. One problem is that the IR panels reduce the amount of exposed wood surface in the sauna which reduces the hygrothermic benefit of soft wood. These panels also produce direct radiant heat, even when turned off, when heated by the sauna heater. This is uncomfortable and results in uneven heating both of which we want to avoid in a sauna.