What is bad indoor climate?

A poor indoor climate is an environment where the air quality is poor and the temperature and humidity are too high or low. This can result in a number of negative consequences such as headaches, fatigue, allergic reactions, irritation of the eyes, nose and throat, respiratory infections and worsening of asthma or other respiratory disorders. A poor indoor climate can also negatively affect productivity and cognitive abilities.

Poor indoor climate can be caused by a number of factors, such as lack of ventilation, pollution, moisture problems, poorly maintained air conditioning or other technical systems, as well as toxic chemicals or materials in building materials or fixtures. It is important to identify the causes and take measures to improve air quality, temperature and humidity in order to maintain a healthy and comfortable indoor climate.

It is important to note that a good indoor climate is not only important for the individual's health and well-being, but it can also have economic and societal benefits, such as improving productivity and reducing sickness absence in workplaces.

CO2 in the indoor climate

In our daily life, we are surrounded by CO2 without thinking about it. But what does it really mean when CO2 levels rise in our indoor environment? Let's dive into this important parameter for indoor climate quality.

What is CO2?

CO2, also known as carbon dioxide or carbon dioxide, is a natural gas that is colorless and odorless. It is found in the Earth's atmosphere as a by-product of various processes, such as hydrocarbon combustion, photosynthesis and respiration.

A typical person exhales about 450 liters of CO2 per day, which corresponds to approximately 900 grams. This happens when we inhale oxygen and exhale CO2 together with other substances through respiration and sweat secretion. Therefore, it is inevitable that the CO2 level also affects our indoor environment.

Why is CO2 a concern?

Although CO2 itself does not pose a direct danger, it acts as an indicator of other pollutants that humans and our environment can emit. Offgassing from furniture, objects and the bio-effluents that we produce through sweat and breathing contribute to elevated CO2 levels in closed spaces.

High CO2 levels can lead to unpleasant symptoms such as headaches, fatigue and reduced ability to concentrate. In addition, it increases the risk of airborne diseases and can worsen the temperature conditions in a room.

Limit values ​​and indicators

Outdoors, the CO2 concentration is usually around 380 ppm (parts per million), but this can vary depending on various factors such as the season.

The Norwegian Working Environment Authority and the building regulations have set limit and indicator values ​​for CO2 levels in indoor environments. For example, the Norwegian Working Environment Authority recommends a CO2 level below 1000 ppm for normal operation in schools, daycare centers and offices.

Actions at high CO2 levels

Although 1000 ppm is not an acute action limit, it signals that ventilation is not sufficient to remove pollutants effectively.

If these values ​​are exceeded, it is important to increase the air exchange, by venting, adjusting the ventilation system or reducing the number of people in the room in question.

Regndråber på vindue

Air humidity and indoor climate

The humidity in our surroundings plays a decisive role in our comfort and health. But what does it really mean when we talk about relative humidity and how does it affect our indoor climate? Let's explore this important parameter in more detail.

What is relative humidity?

Relative humidity is a measure of the amount of water vapor in the air in relation to the maximum amount of water vapor that the air can contain at the current temperature. It is typically stated as a percentage.

When air is heated, it can hold more water vapor, resulting in lower relative humidity. Conversely, when the air cools, it cannot hold as much water vapor, leading to higher relative humidity.

Recommendations and rules

There are various recommendations and regulations regarding relative humidity in the indoor climate, and they vary depending on various factors such as the nature of the workplace and local conditions. The Norwegian Working Environment Authority normally recommends a relative humidity between 25 and 60 percent to avoid discomfort. However, there are also other researchers and experts who give their perspectives on this topic.

Read more in At-guideline A.1.2-1

Effects of humidity on the indoor climate

  • Dry Air: Air with low relative humidity can feel uncomfortable and can cause irritation of the mucous membranes. In addition, it can increase the risk of respiratory diseases and infections.

  • Humid Air: Conversely, too high relative humidity can create a favorable environment for mold and other airborne particles. It can also increase the risk of spreading airborne diseases such as the influenza virus.

Recommendations from experts

Experts like Dr. Peder Wolkoff and Professor Lars Gunnarsen have different views on the optimal humidity. While some recommend a relative humidity of 40-60 percent to reduce nuisance and improve health, others suggest a slightly lower range of 30-50 percent to avoid mold problems.

Read more in Peder Wolkoff's article from 2022 on Videnskab.dk: The right humidity can reduce the risk of influenza (videnskab.dk) and in 'Can 'water' reduce the risk of infection' , which is published in Environment and Health No. 1, May 2021

Regulatory initiatives

Regulation of the humidity in the indoor climate can be achieved through various methods such as humidifying the air. Technological advances have made it possible to develop humidification systems that do not promote the growth of harmful microorganisms.

Read BFA's theme on their portal: Moisture and mould

Experience with humidifying the indoor climate

The indoor climate portal has mentioned two workplaces that humidify the indoor climate. Read about them here:

Gammel radiator med håndtag

Temperature and indoor climate

The temperature in our indoor environment plays a decisive role in our comfort and well-being. What are the general guidelines and how can we ensure comfortable temperature conditions in all indoor spaces? Let's explore this important aspect of indoor climate.

Optimum temperature

To create a comfortable environment, the temperature should generally be between 18 and 25°C, depending on the level of activity and individual preferences. This area allows for a comfortable balance between warmth and coolness that suits most people's needs.

The law and temperature regulation

While there is no specific legislation on temperatures in private homes and other indoor areas, we can look to general guidelines from occupational health and safety legislation as a guide. The Norwegian Working Environment Authority recommends, for example, that the temperature for sedentary work should normally be between 20-22°C and not exceed 25°C.

This is elaborated in the Norwegian Working Environment Authority's guidance no. A.1.12 , which is a guide to interpreting the applicable legislation.

Individual experiences of temperature

It is important to remember that people's experience of temperature can vary considerably. Some may prefer a slightly cooler temperature, while others prefer it slightly warmer. Therefore, it is important to pay attention to individual preferences and adjust the temperature accordingly.

Creation of pleasant indoor conditions

To ensure comfortable temperature conditions, it is important to have a reliable method of regulating the temperature in the home or other indoor environment. This may include using thermostats, radiators, air conditioning or other heating and cooling systems that suit the needs of the room.

Create the ideal indoor climate

Maintaining a comfortable temperature in our indoor environments is essential for our well-being and well-being. By understanding general guidelines and taking into account individual preferences, we can create optimal conditions that promote comfort and productivity in all indoor spaces.

Lampe med cirkulære hvide lamper

The influence of lighting on the indoor climate

Lighting plays a crucial role in our daily lives and can have a significant impact on our health and well-being. From daylight to artificial light, how do different light sources affect us and what measures can we take to ensure a healthy and comfortable light environment?

The importance of daylight

Daylight is not only important for our vision, but it also regulates our circadian rhythm and affects our mood and productivity. Studies have shown that a lack of daylight can lead to negative consequences, including sleep disturbances and low mood. Therefore, access to natural light in our indoor spaces is essential for our well-being.

Artificial light: Good and bad effects

Artificial light can have both positive and negative effects depending on how it is designed and used. Well-coordinated artificial lighting can improve our concentration and productivity, whereas poorly designed lighting can cause nuisances such as headaches and eye strain. It is therefore important to choose light sources and fixtures carefully to create a pleasant and functional lighting environment.

Dynamic light and biological time

Research has shown that light of different levels, colors and directions can affect our biological clock and circadian rhythm. Light in the bluish range, similar to daylight, synchronizes our biological clock and helps regulate our sleep-wake cycle. Furthermore, light has also been shown to affect our hormone production and physiological functions.


The Norwegian Working Environment Authority and the building regulations set requirements and guidelines for lighting in workplaces and other indoor environments. These regulations aim to ensure that the lighting is sufficient for the work tasks, while not causing nuisance or health problems. It is therefore important to comply with these rules to ensure a safe and healthy working environment.

The illuminance, measured in lux, should be appropriate for the type of work being carried out. For most tasks, the recommended level is between 200 and 500 lux, but for work that requires extra light, such as detailed technical drawing or precision work, the illuminance should be around 1000 to 1500 lux for optimum visibility and accuracy.

Artificial lighting - Instructions A.1.5

Future Trends and Technologies

With the rapid development of LED and laser light, new technologies are expected to play a greater role in improving our lighting environment. Future light sources may have antiseptic properties and mimic daylight to further improve our health and well-being.

Creating a healthy lighting environment

Creating the right lighting environment requires a combination of natural and artificial light carefully designed to meet our needs. By choosing high-quality light sources, regulating the brightness and avoiding annoying reflections, we can create comfortable and healthy lighting that supports our well-being in all indoor spaces.

To mennesker i et rum kigger ud af et vindue

The simple way to a better indoor climate

Opening the windows in a room can help improve the indoor climate in several ways:

  • Air exchange : Opening the windows creates a natural air flow that can help remove pollutants and CO2 from the room

  • Humidity control : Open windows lower humidity in the room and prevent mold growth and moisture-related problems

  • Temperature control : Open windows provide cooler air currents that lower the temperature.

However, it is important to note that open windows are not an option in all situations, especially in areas with highly polluted air or noisy environments. In these cases, it may be necessary to implement other measures to improve air quality, such as ventilation systems or air purifiers.

Sundhed.dk (2023).
Indoor climate, overview
Realdania (2020). Socio-economic gains from improved indoor climate.

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