Deep Dive | Optimal humidity in living spaces

Why is humidity important?

Deep dive into the topic:

Between 40 and 60 percent humidity is optimal.

The optimal humidity is between 40 and 60 percent. This range ensures well-being, protects our health, preserves the building structure, and extends the lifespan of furniture, musical instruments, or parquet flooring. Deviations upwards or downwards, however, can cause noticeable discomfort and even damage.

Air that is too dry: An underestimated danger in winter

When the relative humidity falls below 40%, this is referred to as dry indoor air – a common phenomenon in winter, when cold outdoor air in indoor spaces is heavily dehumidified by heating.

Possible consequences:

  • Irritation of mucous membranes (nose, throat, bronchi)

  • Dry, itchy skin and chapped lips

  • Burning or dry eyes

  • Sleep disturbances, increased snoring

  • Higher risk of infection: Flu viruses remain active longer in dry air

Objects also suffer:

  • Wood (furniture, parquet, musical instruments) warps and cracks

  • Paintings or paper products can become brittle

  • Static charge of textiles and plastics

💡 Tip: Ensure sufficient humidity during the heating season, especially in bedrooms and children's rooms.

Air that is too humid: Mold, allergens and energy loss

A permanently high humidity level of over 60% relative humidity promotes microbial growth and also has a negative impact.

Risks of excessive humidity:

  • Mold formation on walls, behind cabinets or on windows

  • Increase in dust mites – bad for allergy sufferers

  • Fatigue and sleep problems due to "heavy" air

  • Higher energy consumption: damp walls insulate less effectively

Particularly at risk are:

  • Bathrooms and kitchens (steam generation)

  • Bedrooms (lots of moisture generated by breathing at night)

  • Basements (cool walls = risk of condensation)

💡 Tip: Ventilate actively after showering, cooking or sleeping. Damp air must be expelled before it settles.

Relative vs. absolute humidity: What matters in everyday life?

The relative humidity (RH) indicates how much moisture is in the air compared to the maximum possible at a given temperature – in percent.

The absolute humidity, on the other hand, measures the actual amount of water in grams per cubic meter. For living spaces, relative humidity is the decisive parameter, as it provides information about the subjective indoor climate.

📏 Measuring made easy: A digital hygrometer helps to keep an eye on humidity. Ideally combined with a thermometer.

Optimal Humidity & Temperature – Explained Room by Room

Optimal relative humidity – Room by room

Room Recommended humidity Ideal temperature Why?
Living room / Office 40–60 % 20–22 °C Frequent occupancy, comfort zone
Bedroom 40–60 % 16–18 °C Less heated, moisture increase at night due to breathing
Children's room 40–60 % 20–23 °C Children react more sensitively to dryness
Kitchen 50–60 % 18–20 °C Steam when cooking → ventilate immediately
Bathroom 50–70 % (short-term) 20–23 °C High moisture peaks, but good ventilation necessary
Basement 50–65 % 10–15 °C Risk of summer condensation – only ventilate when outdoor air is cool

 

Optimal absolute humidity – Room by room

Room Temp. (°C) Rel. humidity (%) Recommended absolute humidity (g/m³)
Living room / Office 20–22 °C 40–60 % 6.9 – 12.7 g/m³
Bedroom 16–18 °C 40–60 % 5.5 – 10.0 g/m³
Children's room 20–23 °C 40–60 % 6.9 – 13.4 g/m³
Kitchen 18–20 °C 50–60 % 7.6 – 11.5 g/m³
Bathroom 20–23 °C 50–70 % 8.4 – 15.6 g/m³
Basement 10–15 °C 50–65 % 4.7 – 8.3 g/m³

📌 Notes:

  • The values are rounded and based on the physical saturation values for water vapor at the respective temperature (e.g., 100% RH at 20°C = approx. 17.3 g/m³).

  • These figures are helpful for professional indoor air analysis or when using dehumidifiers/humidifiers with absolute value display.

  • In everyday life, the relative humidity is usually sufficient as a guideline – however, absolute humidity is particularly helpful for ventilation strategies, e.g., to avoid summer condensation in the basement.


Special considerations in different seasons

  • Winter: Cold outside air is extremely dry → when heating, the relative humidity often drops below 30%. Dry air leads to typical winter complaints (cough, dry skin, susceptibility to infection).

  • Summer: Warm air contains a lot of water vapor. If it gets into cool rooms (e.g., basement), it can condense on cold walls – risk of mold due to summer condensation!

🔁 Correct ventilation:

  • Winter: Shock ventilation 3–4 times a day for 5–10 minutes

  • Summer: Ventilate only when it is cooler and drier outside (morning/late evening)

Measures for a healthy indoor climate

If the air is too dry:

  • Use humidifiers with a hygrostat (clean regularly!)

  • Indoor plants (e.g., spider plant, papyrus, areca palm)

  • Place bowls of water on heaters

  • Hang damp cloths (wet laundry on a drying rack) overnight

If the air is too humid:

  • Ventilate intensively after cooking, showering or sleeping

  • Place furniture away from the wall

  • Use dehumidifiers

  • Ventilate basements only when outdoor air is dry

Conclusion: The right humidity protects people, furniture and walls

An indoor climate with 40 to 60% relative humidity is the key to health, comfort, and the preservation of value in your living spaces. With simple means such as regular ventilation, plants, or mobile technical devices, air quality can be specifically controlled. This makes your home a real place of well-being – in summer as in winter.

Expert knowledge from Stylies, the Swiss manufacturer of high-quality climate control devices, in cooperation with Daniel Gwerder Salesbroker GmbH. For over 20 years, Daniel Gwerder has been dedicated to healthy indoor air and shares his profound knowledge here – understandable, preventive, and practical.

👉 Find out more about Daniel on LinkedIn
👉 Discover Stylies climate control devices at Stylies