DEKRA experts see great potential for a healthier indoor climate
The Perfect Climate Inside the Home
Oct 16, 2026- Rooms are often too humid, too dry, or contaminated
- Periodic ventilation and air purifiers ensure the ideal climate
- Tip: Use a hygrometer to monitor humidity
As a rule, people spend the most time within their own four walls. Surveys show that many of them spend up to 90 percent of the day in closed rooms. But that may not be good for them. DEKRA experts warn that the air inside rooms is often too dry, too humid, stale, or contaminated with harmful substances, dust, or mold – which reduces wellbeing and harbors risks to health. The question is what residents can do to change this and improve the indoor climate.
“Generally speaking, one measure alone won’t create the perfect indoor climate. Like a puzzle, it consists of many small pieces that must be constantly reconfigured,” says Mike Verhoeven, a building expert at DEKRA. Ideally, the temperature inside a home should be between 20 and 23 degrees Celsius, with atmospheric humidity between 40 and 60 percent, the rooms ventilated regularly, and the air largely free from harmful substances.
Air inside rooms often too dry or too humid
Achieving these ideal conditions is often difficult – not just during hot summers. Air that is too humid or too dry is not good for people’s health. Excessive dryness can dry the mucous membranes, cause eye irritations, nosebleeds, and itchy skin, and increase the risk of infection. Too little moisture in the air is also bad for furniture, wooden flooring, and plants. In such cases, a humidifier can help to improve air quality.
By contrast, excessive atmospheric humidity (above 60 percent) can result in mold formation, coughing, sneezing, allergies, and eye and skin irritations, especially in cold rooms. Moreover, condensation and mold can damage walls, fixtures, furniture, and clothing. “If moisture is detected too late, it may also affect the fabric of the building itself,” warns DEKRA expert Verhoeven. That is why cellars and craft rooms should always be checked.
Remove moisture to the outside
The good news is that it is possible to prevent problems by permanently removing high levels of moisture from the air inside a home. It is important to ventilate rooms for a number of minutes several times a day, if possible creating a through-draft. This is effective and saves energy. Important: The steam produced when showering and cooking should not be vented within the home but to the outside. The doors to unheated rooms should be kept closed and furniture should not be placed too close to walls so that the air can circulate. These measures also help to stop mold forming. The DEKRA building expert recommends installing a hygrometer. “This means you can always keep an eye on the humidity.”
Sources of harmful substances in the home
The air inside the home contains many times more harmful substances than the air outside. Regular ventilation is usually sufficient to prevent the accumulation of harmful substances and particulates in rooms. Possible sources of harmful substances are construction materials, paints, furniture, and carpets. In newly renovated apartments and houses in particular, formaldehyde can be emitted from furniture and wooden components and volatile organic compounds (VOCs) from carpet adhesive and paints. That is why it is important to choose low-emission products that have been tested for their environmental compatibility – such as those with Germany’s Blue Angel ecolabel – for renovations and purchases.
Help from air filters and indoor plants
Stoves and open fires usually emit CO, CO2, and soot. Moreover, the air inside rooms can be contaminated by perfume oils, plastic items, and harsh cleaning products. In addition, the printers and copiers used in home offices often emit harmful particulates. Air purifiers fitted with activated carbon filters, for example, help to improve air quality. Certain indoor plants also make the indoor climate more pleasant.
Some modern homes are already equipped with building climate systems that measure various parameters such as temperature, humidity, CO2, and harmful substances and optimize the air quality. Care should be taken to replace air filters regularly (usually every three to six months), ensure the unhindered flow of air, and have the systems serviced by qualified technicians. It also makes sense for users to familiarize themselves with their system’s ventilation functions.
Tips for ensuring a good indoor climate
- Install a hygrometer: The relative atmospheric humidity should be between 40 and 60 percent.
- Rooms should be ventilated several times a day to remove moisture to the outside.
- A humidifier can help if the air is too dry.
- Use an air purifier to remove particulates and harmful substances.
- Choose products with proven environmental compatibility.
- Ensure an optimal indoor temperature of between 20 and 23 degrees.
- Have building climate systems serviced regularly and replace the air filters.
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