Pretty much every sauna has a thermometer.
Many sauna aficionados also have a hygrometer in their saunas. This instrument measures humidity levels, which run from a dry 5% upwards North of 20-30% when we blast some water on the rocks, which creates steam, which is a critical component to a sauna (otherwise it is not a sauna).
“Sauna pros” in Finland, US, and other countries where people are nuts for sauna, can feel a third critically important element to good sauna:
If a good sauna had a Lämpömassa meter, the gauge would go up, as the heat goes up. And the gauge would stay up throughout many situations including when:
- water is tossed on the rocks
- many bodies settle onto the sauna bench
- some yahoo keeps the door open for an extended time
A sauna with good Lämpömassa is a differentiator.
How do we know our saunas have good Lämpömassa without a measuring instrument?
We feel it. Can you feel it?
What makes for good Lämpömassa in our saunas?
- A worthy heat source that produces a shit ton of BTUs.
- A well proportioned mass of stones atop the sauna stove
- A good mass of conductive material surrounding the sauna stove
- Dense walls, either log or well insulated with foil vapor barrier and thicker wood paneling the better.
Why is Lämpömassa so important?
A good sauna provides dense heat. Dense heat heats the entire body. This is when the magic happens. Light bulbs and toaster ovens do NOT create dense heat. This is not temperature and it is not humidity. A Lämpömassa meter will tell you so.