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Documented analyses of the effect of living spaces on the body, grounded in the current state of published knowledge.

Sauna and cold plunge: what the data show, and what they do not

Featured · 6 August 2026 · 9 min read

Sauna and cold plunge: what the data show, and what they do not

The two most requested pieces of equipment in recovery projects rest on very uneven levels of evidence. One is backed by cohorts of several thousand people, the other by a short and contradictory literature.

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0228 July 2026 · 8 min readHumidity: the one quantity that decides what grows in your homeA household produces two to four litres of water vapour a day. What becomes of that vapour depends on a single quantity, relative humidity, and on a single weak point, the coldest surface in the home.

Humidity: the one quantity that decides what grows in your home

0314 July 2026 · 8 min readThe 3-30-300 rule: what a view of nature really changesThree visible trees, thirty per cent canopy cover, a park within three hundred metres. The rule is easy to remember and easy to check. Its evidence base is more uneven than it is usually made to sound.

The 3-30-300 rule: what a view of nature really changes

042 July 2026 · 7 min readMaking it dark: how few lux it takes to suppress melatoninMelatonin does not require absolute darkness, it requires very little light at the right time. A few lux at eye level are enough to hold back its production.

Making it dark: how few lux it takes to suppress melatonin

0525 June 2026 · 7 min readBedroom temperature: why the body has to cool down in order to sleepFalling asleep begins with a drop in core temperature. A bedroom that is too warm prevents that drop, and it is one of the few mechanisms of sleep that can be measured and corrected inside a home.

Bedroom temperature: why the body has to cool down in order to sleep

0611 June 2026 · 8 min readRadon: a gas nothing announces, and two months are enough to measureRadon is odourless, colourless, and causes no immediate discomfort. It is the second leading cause of lung cancer after tobacco, and the only one whose measurement costs a few tens of euros.

Radon: a gas nothing announces, and two months are enough to measure

0721 May 2026 · 8 min readWhat lead is still doing in tap water in 2026Lead no longer comes from treatment plants or trunk mains. It comes from the last few metres: the building’s service line, old risers, solder joints and brass fittings.

What lead is still doing in tap water in 2026

0819 May 2026 · 9 min readFormaldehyde, PFAS, flame retardants: what furniture emitsNew furniture is not an inert object: it releases for months what was used to make it. Here is what is established, what is not, and what can be decided at the point of purchase.

Formaldehyde, PFAS, flame retardants: what furniture emits

099 April 2026 · 7 min readBedroom CO2 at night: why a closed window makes sleep lighterIn a closed bedroom, carbon dioxide climbs while you sleep, often to three times the outdoor value. At those levels it is not a poison: it is the cheapest available marker of air change.

Bedroom CO2 at night: why a closed window makes sleep lighter

1024 March 2026 · 8 min readThe noise you stopped hearing: 53 decibels and sleepYou stop hearing the road after a few weeks, but the overnight recordings do not change. Reported annoyance is therefore a poor instrument, which is why we measure instead.

The noise you stopped hearing: 53 decibels and sleep

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