Notes
Twelve working notes, from cost to chiller sizing in a heatwave
Written for owners, operators and architects who want the arithmetic before the conversation. Numbers come with their sources; rules come with the authority to ask, not a guess.
The 38/4 pair, step by step
The routine, the plant behind it, the arithmetic of heating 1,800 litres and a plain safety note.
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Salt air on timber, glass and steel
Where salt travels, why 316 steel, how timber ages and a yearly checklist for coastal saunas.
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Finnish or infrared, for a villa
Stone heater or infrared panels: temperature, start-up, power and feel, and which suits a villa.
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What a wall of glass costs in electricity
What a square metre of sauna glass loses, why heaters step up for it and what a session costs to run.
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Outdoor sauna cost in euros, line by line
Ranges in euros by size, the nine lines of a quote and what changes by country.
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Cold plunge pools in a Mediterranean summer
Four sources of heat, three chiller classes and the shade and cover that matter more than a bigger machine.
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From sea swimming to sauna and cold dip
The Irish habit, the cabin and cold dip it asks for at home, the deck that makes it work in November.
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A sauna and plunge circuit for lets
From check-in to changeover: guest flow, covers, the cleaner's routine, registration and the listing.
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Outdoor sauna permits, country by country
What we could verify on official sources in four countries, and the five questions to put to any town hall.
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Single-phase or three-phase at the villa
Amps for a heater and a chiller, when single-phase is enough and what to ask your electrician.
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Keeping a shared plunge pool clean
Filtration, UV, ozone and chlorine, bather load, water changes and the log sheet that proves it.
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Recovery rooms members actually use
Size by the match, run it by a rota, draw the floor for wet feet and leave out what you will not clean.
Read onSections on this page
Missing a topic? Send the question on WhatsApp and the note may become the thirteenth.
By topic
- Money: what a custom outdoor sauna costs; the energy of a glass cabin.
- Rules and power: permits compared; villa mains or three-phase.
- Heat and cold: cold plunge in a Mediterranean summer; how a 38/4 pair works.
- The coast: salt air, timber, glass and steel; from sea swimming to sauna and cold dip.
- Business: holiday-let circuit; padel clubs and gyms; hygiene for commercial pools.
- Choosing: Finnish or infrared.
Three reading orders
- A villa owner: start with what an outdoor sauna costs, then permits compared, then villa mains or three-phase.
- A hotel or club operator: start with hygiene for commercial plunge pools, then the holiday-let circuit or recovery rooms for clubs.
- An owner on the Atlantic coast: start with salt air, timber, glass and steel, then the energy of a glass cabin, then sea swimming to sauna and cold dip.
How these notes are written
Each note gives its numbers with a source and a year, separates what we could confirm on an official text from what you must ask your authority, and says when a figure is our own arithmetic. The notes are dated October 2026. Rules change, so a note that cites a regulation names it, and the date it was read, so that you can check it is still current. If you spot a mistake, say so on WhatsApp and the page is corrected.