While there is a vast variety of different types of saunas, the fundamental difference comes down to three different types of saunas, defined by different heating methods.
This type of saunas is what most people imagine when they think of saunas. In a continuous heating sauna, a heater – usually electrical but alternatively also wood or coal fired – is used to heat up the sauna room to your desired temperature of typically between 70 and 100 degrees. The heater then continues heating the sauna while you use it. Most Finnish style saunas use this type of heating. In fact most of the heaters actually come from Finland.
In heat storage or pre-heated saunas the heating takes place before you use the sauna. Usually several hours before you use it. These saunas are equipped with a large thermal mass, typically meaning several hundred kilograms of stones surrounding a wood or coal heater. This thermal mass is heated up for several hours before you use the sauna. The fire is then put out and the sauna retains its heat simply from the heat stored in the thermal mass. Banyas and outdoor Finnish saunas often use this technique.
Infrared saunas use an altogether different technology. An infrared sauna does not heat the sauna room but instead transfers heat directly to your skin. In this type of sauna infrared light emitters are installed in the walls, benches and ceiling of the sauna. The infrared light emitted is invisible to your eyes and turns into heat as it gets absorbed by your skin. The major differences to the other types of saunas is that infrared saunas require little or no pre-heating and much less thermal insulation, which in turn means that they offer more design freedom, such as including large glass walls.
Based on these three different types of heating, a few notable types of saunas, with familiar names, exist.
A Finnish Sauna uses either continuous heating or heat storage and operates at the higher end of the temperature range. Water can be splashed on the heater or the thermal mass to increase humidity but the sauna is mostly enjoyed dry.
The Smoke Sauna is a special type of saunas using the heat storage method. Instead of venting the smoke from the fire that is used to heat up the thermal mass, the smoke is ‘trapped’ inside the sauna room. Over time this darkens all surfaces inside the smoke sauna and it gives the sauna a particular, smoky feel and smell. To avoid soot from covering the benches and eventually you, we typically build smoke rooms in such a way that you can remove the benches during the heating phase.
The typical Russian and Eastern European Banya falls somewhere between the steam bath and the sauna. While the Banya looks like a sauna, it continuously uses water to maintain a constantly high humidity level and steam concentration. If you do not have space for a steam bath and a sauna, the Banya is an interesting alternative.