[Draft]
A Thermal Suite is exactly what the name implies – a collection of thermal experiences.
It can be as simple as a sauna, shower and a place to sit outside or a complex with dozens of experiences such as Tropical Islands or Therme Erding.
A typical residential thermal suite might include a common area with cold plunge, showers and lounge chairs, a 4 person sauna, a 4 person steam bath / thermarium and a hot tub / vitality pool outside.
What’s A Spa? – Traditionally a spa is a pool of naturally heated mineral water to bathe in. Unless you have a hot spring you don’t really have a spa. Recently we Americans, as we’ve done with many words from Europe, have tried to apply it to anything and everything thinking it makes us sound more sophisticated. The result is that words completely lose their meaning. Big deal? Not particularly. But some people view those using terms like spa incorrectly as kind of ignorant. So better to use ‘thermal suite’, ‘salon’, ‘hot tub’ or ‘vitality pool’, ‘beauty parlor’, ‘resort’ or whatever word better and more accurately describes what we’re talking about.
There are several foundational elements to keep in mind throughout the design process as a whole and for each space.
Hot, Cold, Rest, Rinse, Repeat
Thermal experiences rest on a foundation of Hot, Cold, Rest, Rinse, Repeat. Whether for simple enjoyment or gaining health and wellness benefits we want to be able to comfortably do multiple hot cold rounds – contrast therapy.
Our thermal suite should support this with dedicated areas for each Hot, Cold, Rest and Rinse. And the ability to move comfortably and easily, while nude and wet, between them.
- Hot – Sauna, Steam Bath, Vitality Pool (hot tub)
- Cold – Outside air, Cold Plunge, Avanto, Snow Room, Rolling in the snow.
- Rest – Benches, lounge chairs, reading nook, café
- Rinse – Showers, Dump Buckets
Social
Thermal suites are a social space. An area to enjoy alone, with family and with friends.
It should be a space that’s aesthetically pleasing and where we and others enjoy spending time.
The indoor and outdoor common areas should include areas to socialize while we rest between rounds.
There’s a balance of maintaining social connections with privacy that we’ll get in to later.
Hygiene
A thermal suite can be a haven for bacteria and other undesirable gook but good design can make it much easier to avoid problems.
Nude – Textiles such as swimsuits are impossible to keep bacteria free and similarly any skin covered by textiles will become a bacteria factory. Insuring that people are comfortable being nude is critical.
Showers – We want to make rinsing frequently as quick, easy and enjoyable as possible. Everyone should rinse at least once per round and twice per round is not unusual.
Surfaces – As much as practical we want to use surfaces that are easy to keep clean such as tile.
Access – We should be able to easily access areas for cleaning such as under the benches of a sauna. Similarly we should avoid creating difficult to clean places.
Storage – Keeping cleaning supplies easily accessible makes cleaning easier and so we are more likely to do it frequently.
Water – Being able to easily hose things down is a wonderful thing.
Inside / Outside
A connection to outside makes for a more enjoyable experience. Ideally we want a common area that is contiguous inside and outside both physically and visually.
Physically – At a minimum we should be able to easily walk outside to cool off and get some fresh air each round. This without traipsing through public areas or any areas where dripping water would be unwelcome.
Better is if the common area has an outside wall with doors and windows and better still with sliding doors that can largely eliminate any separation when weather conditions are appropriate.
In very temperate areas the common area can be completely outside.
Visually – Natural sunlight and moonlight are much more pleasant than articial light and being able to see outside is usually quite relaxing. So lots of glass windows and doors is a good thing.
A full or partial conservatory or orangery can make for a wonderful common area. Shades to reduce sun on us are beneficial however.
Inside Only – If the thermal suite is entirely inside then we need to insure a comfortable place to rest.
Nude
Thermal experiences are all best enjoyed nude. And yes, even for groups of mixed sex. This influences our design in two ways;
Privacy – We want to be able to relax and that’s difficult, particularly for Americans, when we feel exposed. We want to feel protected throughout our thermal suite from outside as well as within it.
Hygiene – If we are nude and practice good hygiene then the bacterial loads in pools and elsewhere are much lower than if we wear swimsuits.
For more see Saunas, Nudity & Victoria in the menu above.
Regard For Others
Not a design element but critical. Everyone must have regard and consideration for everyone else. This goes from not staring at people to being calm and quiet so that we don’t disturb others.
Common Area
This is the space that connects everything together and usually includes places to rest, a cold plunge and several showers among other amenities.
It can be purely inside, purely outside, or a combination of both. A common area that’s contiguous inside and outside works very well.
Like all areas of a thermal suite this is a wet area so should support people walking around wet and should be able to be hosed down for cleaning.
Aesthetics – We’ll typically spend a lot of time here (and if well designed then even we’ll spend time here even when we’re not utilizing any thermal experiences). Simple and calming are good but some might prefer a more ornate area.
Floor Surfaces – The surfaces of floors should be non-slippery but also not rough. They should be comfortable to walk and stand on barefooted.
Heated Floors – In colder environments all of the floors of the commons, sauna and steam baths should be heated.
Hooks – Lots (and lots and lots) of hooks to hang towels and robes on.
Porch
A covered area that allows people to go outside when its raining or snowing is a very good addition. This can also protect against sun.
Showers
A key for the showers is quick and easy. We want ourselves and others to rinse frequently. Doors, curtains, and circuitous routes all add difficulty so avoid those. Similarly, we want to be able to maintain uninterrupted social connections so should be able to maintain conversations while showering.
About one shower for every two people works well though more than that can reduce problems of having to wait on others.
Thermostatic Controls – Good thermostatic controls that provide accurate and consistent water temps are worth the cost.
Shower Head Configuration – A single fixed head can work but a hand-held on a rail is better. Best is to have both a fixed head (wall mounted or rain) and hand-held.
Shower Heads – For a single wall mounted fixed head I don’t think a traditional Speakman can be beat. Avoid head with wide spray patterns as these can result in others being accidentally sprayed.
Foot Wash – A foot wash, as part of a shower unit or separate, can help to keep floors from getting gritty. A separate dedicated foot wash near the entry door from outside works well.
Experience Showers – There are a variety of options for these. Personally I’m not a big fan but many people like them.
Configurations
Best and least expensive is a simple Open Line along a wall of the common area with a single trough drain. Heads here should be spaced about 750mm to 1000mm, or more, apart.
Two showers on a common area wall. The glass wall sauna creates a privacy problem for both those in the sauna and those showering – a solid wall would have been better here. I would also prefer a trough drain near the wall.
Two showers on wall just outside the sauna. Note the exhaust vent on the ceiling above. Again, I would have preferred a single trough drain near the wall.
Dividing walls that create open 3-Sided Cubicles can provide a bit more privacy. Each cubicle should be about 800-850mm wide and deep though larger is certainly fine. Dividers can be tiled walls, frosted glass, or stainless steel. Tile is much easier to keep looking clean.
A slightly more private Open 4-Sided Cubicle would be perhaps 900 x 1400 with the shower head on one end and an open entry on one side of the other end.
Two Open 4-Sided Showers Cubicles. The one on the far end provides the most privacy for those who desire it. The door on the right leads to the sauna.
Finally, a combination can work well. So perhaps an Open 4-Sided Shower Cube on the far end of a wall with a 3-sided next and then two on a common wall provides space for four people at a time with varying levels of ease vs privacy.
It’s best, particularly for open showers along a wall, for water to drain towards the wall to a trough drain. This avoids having others rinse water running across our feet, provides for a flatter surface to stand on, and is often less expensive than a round drain that requires more effort for sloping tile correctly.
Front to front facing showers can be awkward and are best avoided of possible.
Dump Buckets
Dump buckets are a wonderful way to cool down and rinse off.
Privacy
We want to maintain privacy to/from outside of the thermal suite as well as within.
Inside – This is the easiest since you can simply build walls to cordon off the thermal suite from view of the rest of the house. But it still requires careful planning.
Outside – Preserving privacy outside requires a bit more thought and effort but is worth it to provide a comfortable cooling off space, outdoor cold plunge or vitality pool.
Fences and hedges are the most obvious elements for this.
A sunken patio area can help.
I consulted on one project near Los Angeles where about half the back yard functioned as the common area. The sauna and steam bath were in two separate buildings. Cold plunge, vitality pool, showers and loungers were scattered about the outside area. There was a hedge/fence along both sides to screen from neighbors. The side away from the house was a hillside overlooking a populated valley so it had a short hedge that provided a bit of privacy from people in the valley but still allowed a good view.
Within – While we may be comfortable being nude amongst others in the thermal suite, we also don’t want to be on display. As well, some people are self conscious about showering.
It’s generally best for saunas and steam baths to have limited windows in to the common area. A glass door is good and maybe a smaller window. One exception is if there is a fantastic view to be had but even then the amount of glass should be limited and kept higher up.
Ventilation
Saunas and steam baths should have their own separate and dedicated ventilation systems.
Common Area Ventilation – Should be its own separate dedicated system providing about 10 l/s (20 CFM) per person. A system that varies ventilation rates based on CO2 can save energy while also providing adequate ventilation to maintain healthy CO2 levels and air quality.
Common Area Heating – Best provided by in-floor hydronic.
Common Area Cooling – This can be a bit more difficult in warmer climates where opening windows or going outside doesn’t suffice.
A separate and dedicated forced air cooling system, either central or mini-split, is the best option. Note that the capacity must be designed for the higher humidity of this area.
Using the forced air cooling of a home combined with a good dehumidifier can sometimes work though is not ideal.
Note that radiant cooling is not a good option due to the higher humidity of the common area which will result in condensation on the cooling surfaces.
Common Area Temps – About 22°c seems a good temp to balance comfort with being able to cool down.
Lighting
Lighting is important and too often not given the attention it deserves.
Natural – Start with natural light from the sun, moon and stars. This via doors, windows, conservatories, skylights or light tubes.
Artificial Light:
Color Quality – Older incandescent lights provided a warm and comfortable full spectrum color quality and temp. LED’s and other sources don’t so so well. A high CRI (color rendering index) is good but is easily manipulated by manufacturers so look also for a high R9 (red) value of 85 or better. Better yet is a high TM-30 score.
Flicker – Some LED’s have a flicker that can cause headaches for some people. Something to be cautious of.
Color Temp – Warmer is generally more pleasing and relaxing than cooler. 2400-3000°k works well.
Colors – Colored lighting can work well. The best option here I believe is for each fixture to be individually controllable. We use Hue GU-10 downlights which allows us to create a number of different scenes from basic warm white to cooler blues and greens or warmer yellows, oranges and reds.
Light & Shadows – Shadows are just as important as lighted areas and create for a pleasing environment.
Privacy – Using dimmer levels/colors overall and in particular for showers can make people feel more comfortable.
Cleaning – For cleaning its good to have a lot of bright and shadowless light.
GWI’s Hydrothermal Guide – Though intended for commercial facilities, a home thermal suite isn’t too dissimilar so much of what’s in here applies.