Indoor climate

Most of us spend 80-90% of our lives indoors. The indoor climate therefore is of vital importance to our well-being.

Several factors affect the indoor climate:

  • Moisture from ourselves, from drying clothes, cooking and hot water.
  • Pollution from the air outside (traffic and wood stoves)
  • Dust, pollen and mould spores
  • Substances from pets

Chemicals from cleaning products, candles, furniture, electronics, toys and construction materials also affect the indoor climate. Airing out 2 x 5 minutes every day and keeping the home clean and free of moisture ensures the best conditions for a healthy indoor climate.

Humidity of 45 percent at a temperature of around 20 degrees is optimal for our organism.

Air out 2 x 5 minutes
every day


Fugt er en af de vigtigtste faktorer at holde i skak, for at opnå et sundt indeklima. Fugt giver nemlig gode vækstbetingelser for skimmelsvamp og husstøvmider, og nedbryder samtidig byggematerialer. Derved afgives organiske materialer og kemikalier til luften, som kan irritere dem der udsættes for dem.

Symptomerne ses som irritation i øjne, næse og øvre luftveje, hovedpine, træthed, hoste og hududslet. Personer med høfeber og astma er særligt følsomme. Desuden kan det give øget risiko for luftvejsinfektioner.

A family of two adults and two children emit about 10 litres of water a day to their home. Laundry hung indoors adds at least 2 litres per wash.

If there is high humidity in the home, it is often seen as indoor condensation on cold surfaces such as windows. Condensation on windows with only one layer of glass will always occur, but is not normal on double glazing.

Condensation can also form on cold surfaces in places with poor insulation (cold bridge) or on the internal walls between unheated and heated living space. A room should not be colder than 17-18 °C at any time. This is also true in the bedroom. If a room generally has a bad musty smell, it is ALWAYS a sign of high humidity and mould growth.

In order to avoid condensation indoors, keep a constant and uniform temperature between 20 and 22 °C and relative air humidity (RH) between 50 and 60% in every room. (RH in winter should be around 40%). This also applies to rooms which are not used as often. The actual RH in a room can easily be measured using a hygrometer.

Mould grows especially on (or behind) wallpaper, wood, paint and plasterboard. Conditions will be ideal when the aforementioned organic materials have a moisture content corresponding to RH of 75-80%.

If moisture damage occurs, it should therefore be repaired as soon as possible. If moisture damage is left untouched for several weeks, it will often result in the development of mould growth and thus the release of spores into the air indoors.

Dust mites also thrive best in a moist environment, especially in the bedroom. In addition to the frequent change of bed clothes, this is yet another good reason to keep a low RH.

5 good reasons to keep relative humidity inside the home at between 50-60%:

1. Counteracts mould growth
2. Prevents bad odours
3. Ensures a healthy home and interior
4. You get a good night's sleep
5. Reduced risk of allergies

Moisture when it is cold

The air indoors is drier in the cold months, affecting moisture balance in the skin, interior and structural parts in wood.

We usually first notice this on our lips, but irritated, dry eyes and itching are also a sure sign. And just as we humans need water to keep skin strong and healthy, furniture and structural parts in the home also need moisture to stay nice and healthy.

Short-term remedies can be a good moisturising cream, eye drops, and for furniture, a good furniture oil. A more enduring solution though is to make sure that RH does not fall below 45%.

Læs mere om luftbefugtere her

The relative humidity in winter should not get below 45%.

Dust and pollen


Dust has a large surface, providing plenty of room for dust mites, pollen, mould spores and other things from ourselves and our pets. Phthalates also find space in dust around the home. The longer dust is allowed to accumulate, the more substances can gather.

Studies from 1998 show that 7.1% of all Danes suffer from dust mite allergy. The number is probably higher today. The current estimated is about 10%. 50% of all asthma patients are also sensitive to dust mites.

Clean air in the living room – and especially in the bedroom – means a great deal to our general well-being, even if we are not suffering from allergies. A dusty environment can cause symptoms such as headaches, difficulty concentrating, irritated eyes, allergies and asthma.

Read more about air purifiers.


If you have hay fever and are allergic to pollen, airing out early in the morning and late at night when there is a minimum of pollen in the air is generally recommended. Avoid drying clothes outdoors in season, since pollen will attach to the fabric, causing you a lot of problems.

You can't avoid pollen being brought into the home from the outside. It comes in on your hair, clothes, shoes, bags and through ventilation ducts, etc.

Vacuuming at least once a week is necessary, organising the home to make it easy to clean is recommended. Make sure that your vacuum cleaner can get everywhere – especially under the beds and sofas where dust loves to gather.

An air purifier with an ionised HEPA filter is a good solution for an allergenic and dust-free indoor climate.