Everything you need to know about the air exchange rate

The air exchange rate is a decisive factor for air quality and energy consumption in buildings. Whether you are planning a new building project or carrying out a comprehensive refurbishment, understanding and correctly calculating the air exchange rate is essential to ensure both comfort and efficiency in your project. Whether in homes, offices or schools, the air exchange rate plays a crucial role in people’s well-being and health. In this article, you will learn what the air exchange rate is, why it is important and how to calculate it correctly.  

What is the air exchange rate?

The air exchange rate (AER) indicates how often the air in a room or building is exchanged within a certain period of time. It is usually expressed as the number of air changes per hour (h-¹). An air exchange rate of 0.5/h means that the air in the room is completely exchanged twice within an hour. A higher value means that the room air is renewed more frequently, resulting in better air quality. It is important to understand that the air exchange rate not only depends on the size of the room, but is also influenced by other factors such as the utilisation of the room, the number of people in the room, the furniture and appliances present and the condition of the building. The air exchange rate plays a crucial role in controlling air pollutants, regulating humidity and preventing mould growth. Adequate air exchange ensures fresh air in the room and helps to improve indoor air quality.  

Why is the air exchange rate important?

The air exchange rate is a decisive factor for the air quality in closed rooms and buildings. The regular exchange of stale air with fresh outside air ensures that pollutants, moisture, odours and other unwanted particles are effectively removed. A sufficient air exchange rate helps to create a healthy and pleasant indoor climate that has a positive effect on the health and well-being of the occupants or users. The air exchange rate is becoming increasingly important, especially in times when indoor air quality is playing an ever greater role. It helps to keep the concentration of air pollutants such as CO2, VOCs (volatile organic compounds) and mould spores at a low level, which can reduce the risk of health complaints. Adequate air exchange is also very important for preventing moisture problems and mould growth. Continuous air exchange regulates humidity, which helps to preserve the building fabric and prevent structural damage. The air exchange rate also plays a decisive role in the energy efficiency of buildings. Targeted control of ventilation systems can optimise energy requirements for heating and cooling, which can lead to cost savings in the long term.  

The most important arguments:

1. Improved air quality: an adequate air exchange rate helps to remove pollutants, CO₂ and moisture from the room, resulting in a better indoor climate and comfort.
2. Moisture protection: Especially in moisture-prone rooms such as kitchens and bathrooms, a sufficient air exchange rate prevents the formation of mould and other moisture problems.
3. Energy efficiency: The right balance in the air exchange rate helps to optimise energy consumption by enabling efficient use of heating and cooling systems.

Factors that influence the air exchange rate

There are various factors that influence this rate. For example, the air exchange rate can vary depending on the type of room. In residential buildings, a lower air exchange rate is often aimed for, while in certain environments such as laboratories or production facilities, a higher air exchange rate is required. One of the most important influencing factors is also the size of the room. The larger the room, the more air needs to be exchanged to ensure optimum air quality. The number of people in the room also plays a role. People continuously exhale air and produce CO2, which must be removed in order to supply fresh air. Room type and utilisation should also be taken into account:

In Germany, specialist planners are guided by DIN 1946-6 for residential ventilation and DIN EN 16798-3 for the ventilation of non-residential buildings. These standards specify detailed guide values that vary depending on building utilisation and room type. By complying with these standards, you can ensure that your ventilation systems fulfil the legal requirements and at the same time provide a comfortable indoor climate. Other important factors are the room temperature and humidity. High temperatures and humidity can have a negative impact on the air exchange rate, as the air becomes polluted more quickly. At the same time, external factors such as the outside temperature and the air quality outside also influence the air exchange rate inside a building. Accordingly, the building envelope and density and placement of windows will affect the air exchange rate.

In this context: In modern, well-insulated buildings, precise control of the air exchange rate is required to avoid energy losses due to excessive ventilation. Systems with heat recovery can be particularly advantageous here. These can ensure an efficient air exchange rate, whereas natural ventilation systems can vary depending on weather conditions. To achieve an optimal air exchange rate, all these factors must be carefully considered. A balance between air supply and extract is crucial for the health and well-being of the occupants and contributes significantly to the energy efficiency of a building.  

Summary: Ensure ideal air exchange

The following measures should be taken into account to optimise the air exchange rate:

1. Selecting the right ventilation systems: Decentralised ventilation systems such as those from Ventomaxx allow the air exchange rate to be precisely adapted to the needs of each room. Systems with heat recovery also contribute to energy efficiency.
2. Regular maintenance and filter replacement: To ensure consistently high air quality and efficient air circulation, regular maintenance of the ventilation systems and replacement of filters is essential.
3. Consideration of room size and use: Adapt the air exchange rate to the specific use and size of the room. In offices or schools, additional ventilation openings or more powerful systems may be required to cover the increased air requirements.
4. Integration of hygrostat functions: Modern ventilation systems are often equipped with hygrostat functions that automatically measure the humidity and adjust the ventilation accordingly. This helps to optimise energy consumption while maintaining a comfortable indoor climate.

Decentralised ventilation systems and air exchange rate

Decentralised ventilation systems play a decisive role in regulating the air exchange rate in buildings. These innovative systems enable efficient ventilation of individual rooms without having to rely on a centralised ventilation system. By individually controlling the air supply and extraction, you can adjust the air exchange rate to the needs of the respective environment.

1. individual adjustment of the air exchange rate Decentralised ventilation systems enable precise control of the air exchange rate in each room. This means that you can fulfil specific requirements for different rooms, such as higher air exchange rates in kitchens or bathrooms and lower ones in bedrooms. This improves comfort and can help to reduce energy costs by only renewing the amount of air that is actually needed.

2. flexibility of installation Decentralised ventilation systems offer great flexibility in installation, especially in renovation projects where a central ventilation installation may not be able to be retrofitted. Decentralised systems are often compact and can be easily integrated into existing structures. The installation of decentralised ventilation units can make a costly redesign of the building infrastructure unnecessary. Thanks to their modular design, they can also be installed retrospectively, which is particularly advantageous for renovation or refurbishment projects.

3 Energy efficiency and heat recovery Many decentralised ventilation systems are equipped with heat recovery functions. This means that the warm air removed from the room is used to preheat the fresh supply air. This optimises energy efficiency and reduces heating costs.

With systems such as the Ventomaxx WRG RONDO and WRG PLUS, you can achieve high energy efficiency by utilising the heat from the extract air to preheat the supply air. This is particularly advantageous in well-insulated buildings, where precise control of the air exchange rate is crucial. Overall, decentralised ventilation systems offer an efficient and flexible solution for controlling the air exchange rate in buildings. Thanks to their simple installation, individual control options and contribution to the quality of living, they are a forward-looking option for healthy and comfortable indoor air.  

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In the world of ventilation technology, sound information is essential to ensure an optimal indoor climate and to work in an energy-efficient manner. The resources mentioned offer a wide range of insights into relevant topics and present useful concepts for practical use. The air exchange rate plays a crucial role in indoor air quality. By calculating and optimising the air exchange rate, you can ensure that your rooms are always supplied with fresh air.

Take into account the various factors that can influence the air exchange rate and make sure you comply with the specifications to ensure an optimal indoor climate. Decentralised ventilation systems offer an efficient way to optimise the air exchange rate in your building and thus ensure a healthy and comfortable indoor climate.

Ensure that the air exchange rate in different environments meets your requirements to create ideal conditions. With proper consideration of the air exchange rate, you can create a comfortable and healthy indoor climate. At Ventomaxx, we understand the importance of the correct air exchange rate to the success of a building project. Our flexible and highly efficient ventilation systems offer you customised solutions for every requirement. With over 20 years of experience and a strong focus on quality and customer service, we are your expert partner. Let us advise you and find the perfect solution for your ventilation requirements.