In architectural design, the air-tightness of buildings is playing an increasingly central role. But what does this term mean and how does it affect our daily lives? The air tightness of a building envelope describes how well a building is protected from uncontrolled air exchange with the environment. An air tight envelope is of great importance, both for the indoor climate and for the energy efficiency of a building. With increasing awareness of sustainability and environmental protection, air tightness is becoming an ever more important focus for the construction industry. In the following article, we take a detailed look at the air tightness of buildings, explain its importance, discuss relevant regulations and standards, and shed light on the effects of poor air tightness. You will also learn more about air tightness measurement using the blower door test and why decentralised ventilation systems offer an effective solution. Join us as we explore the world of air tightness and discover why an air tight building is more than just a facade.
What does air-tightness of buildings mean?
Airtightness of buildings An airtight building ensures that ventilation can be controlled in a targeted manner, which is crucial for energy efficiency and the indoor climate. This means that heat can be kept inside the building in winter and kept out in summer. This not only helps to reduce heating and cooling costs, but also creates a pleasant and healthy indoor climate. It is important to understand that air tightness is not the same as air sealing. Air tight buildings prevent unwanted air exchange, while air sealing measures are used to prevent moisture from entering the building structure. To create a well-insulated and energy-efficient building, it is crucial to consider air tightness from the beginning of the construction planning and to carry out control measures during the construction process. Airtight building envelope Let's take a closer look at the concept of the ‘airtight building envelope’: in simple terms, this means that the building envelope is designed in such a way that air leakage is minimised. In new buildings, the focus is increasingly on achieving a high level of air tightness. This is due to the need for more energy-efficient buildings in order to meet strict regulations and reduce the ecological footprint. Building owners and architects are now paying particular attention to ensuring that the building envelope is well sealed to prevent air leakage. An important aspect of modern construction is the use of advanced building materials and techniques to improve the air tightness of the building envelope. From specialised sealants to high-quality insulation, every component of the construction process is optimised for better air sealing. Building regulations and standards have also evolved to emphasise the importance of an airtight building envelope. Regulations now require rigorous testing and verification of a building's airtightness to ensure compliance with energy efficiency guidelines.
Why is air tightness important for a healthy indoor climate?
Airtightness is a crucial factor for a healthy indoor climate. If the airtightness is insufficient, various negative effects can occur. Uncontrolled air exchange can result in problems such as draughts, uneven distribution of humidity and unwanted heat loss. Uncontrolled air flows can result in uneven temperatures in the rooms. Good air tightness provides control over the air exchange within the building, which has a positive effect on the comfort of the occupants. Another problem caused by a lack of air-tightness is energy loss. Valuable heating energy can escape through leaks in the building envelope, resulting in higher heating costs and increasing the environmental impact due to higher energy consumption. Humidity that enters the building through leaks can lead to mould and structural damage. Good air tightness helps to avoid these problems and thus to preserve the building fabric and interior fittings in the long term. Furthermore, air leaks in the building envelope can result in unwanted external noise, which can significantly impair the comfort of the living space. This disturbs the residents and prevents them from relaxing or working in peace. Airtight buildings also have the advantage that pollutants and allergens from the outside air cannot penetrate unhindered. This makes a significant contribution to improving air quality and protects residents from health problems. In addition, airtightness ensures that the ventilation technology used can work efficiently, as no unwanted air currents impede the exchange of air. To avoid these negative effects, careful planning and implementation of airtightness is crucial. Modern ventilation systems, such as decentralised ventilation solutions, can help to improve airtightness and ensure a healthy indoor climate.
The role of the Building Energy Act (GEG) in ensuring the air-tightness of buildings
The Building Energy Act (GEG) plays a crucial role in ensuring the air-tightness of buildings, as it sets binding standards for reducing energy consumption and improving energy efficiency. A central requirement of the GEG is to ensure a high level of air-tightness of the building envelope. This measure is of great importance in minimising energy losses due to uncontrolled air flows, so-called thermal bridges. Airtight building envelopes prevent heat from escaping unintentionally, which significantly reduces heating requirements and thus energy costs. In addition, improved airtightness helps to increase living comfort and prevent structural damage caused by humidity, such as mould formation. The GEG therefore not only promotes climate protection, but also the value retention and longevity of buildings. The Building Energy Act (GEG) explicitly refers to the air-tightness of buildings in several paragraphs, in particular with regard to the energy requirements for the building envelope. The wording of the law requires that buildings must be constructed in an ‘air-tight’ manner in accordance with the state of the art. This is stipulated in particular in § 13 GEG, which regulates the requirements for air-tightness. In detail, the GEG requires that the airtightness of the building envelope is ensured in order to minimise energy loss through uncontrolled air flows, also known as infiltration. The law allows the use of ventilation systems that can contribute to controlled ventilation and extraction, as long as they do not compromise energy efficiency requirements. The so-called blower door test is often used to check the air-tightness of a building. This test measures the air exchange rate of a building and ensures that the legally defined limits are adhered to. In summary, the GEG ensures that the energy efficiency of buildings is increased, energy consumption is reduced and living comfort is improved by imposing strict requirements on the air tightness of the building envelope.
Air tightness measurement: Blower-Door-Test
The blower door test is an essential procedure for measuring the air tightness of buildings. It is a method in which a fan is installed in a door or window of the building to determine the air permeability value. The pressure difference between the inside and outside can reveal potential leaks in the building envelope. During the test, the building is subjected to positive or negative pressure in order to identify weak points in the air-tightness. Special software measures the air permeability and enables targeted and efficient improvements. The results of the blower door test are of great importance, as they not only provide information about the air tightness, but are also decisive for the energy efficiency and comfort in a building. Good air tightness ensures reduced heat loss and prevents unwanted air exchange. The repair of leaks that are revealed by the blower door test can result in a significant reduction in energy consumption. The test is therefore not only important for identifying weak points, but also for improving the energy balance of a building.
Why decentralised ventilation systems are essential for air quality and comfort in airtight buildings
Decentralised ventilation systems provide an efficient solution for air circulation in buildings and make a significant contribution to improving the indoor climate. Decentralised ventilation allows individual rooms to be ventilated as required, without ventilating the entire building. This ensures optimal air quality and a pleasant living or working environment. Decentralised ventilation systems are essential in airtight buildings for several reasons: Air quality and humidity control: In airtight buildings, uncontrolled air circulation is minimised to reduce energy loss. However, this can also result in a decrease in indoor air quality, as pollutants, CO₂ and humidity are not adequately removed. Decentralised ventilation systems ensure a continuous air exchange, which is necessary to keep the indoor air fresh and to regulate humidity, which also prevents mould and other moisture damage. Energy efficiency: decentralised ventilation systems, especially those with heat recovery, allow fresh air to be introduced without losing the entire heat content of the interior. These systems are designed to use and reuse the energy that is already present in the building, which further increases the building's energy efficiency.Comfort and health: Good ventilation is essential for the comfort and health of the occupants. Decentralised ventilation systems help to maintain a comfortable indoor climate by ensuring that the air is not only renewed but also maintained at the correct temperature and humidity.Avoiding over- and under-pressurisation: In airtight buildings, over- or under-pressurisation can occur due to insufficient ventilation. Decentralised ventilation systems help to avoid these pressure imbalances by ensuring a continuous air flow and thus a stable indoor climate. Overall, decentralised ventilation systems help to overcome the challenges of airtight construction by ensuring the necessary ventilation, optimising energy efficiency and improving the quality of life in the building. The airtightness of buildings is an important issue that should not be underestimated. An airtight building envelope not only protects against heat loss and moisture damage, but also contributes significantly to a healthy indoor climate. Regular airtightness measurements such as the blower door test can be used to check and optimise the quality of the building envelope. Compliance with regulations such as the Energy Saving Ordinance is of great importance. A lack of air tightness can result in energy losses and mould formation. Efficient ventilation can help to remedy this and contribute to creating a healthy and energy-efficient indoor climate. Ultimately, it is clear that the air tightness of buildings has a decisive influence on comfort, energy efficiency and sustainability.
