Why is airtightness important?
An airtight building envelope is essential for achieving modern energy-efficiency standards, both in new buildings and in the refurbishment of existing properties. It prevents uncontrolled airflow through joints and leaks, helping to reduce energy losses, protect the building structure against moisture damage and improve indoor comfort. Energy-efficiency measures such as modern heating systems or high-performance windows can only deliver their full benefits if the building envelope remains airtight over the long term.
Airtightness and controlled ventilation
The misconception that buildings need to “breathe” through gaps and cracks is still widespread. In fact, uncontrolled air exchange does not improve air quality or create a healthy indoor climate. On the contrary, allergens and dust from insulation can mix with indoor air when air enters the building through leaks in the envelope. The necessary supply of fresh air should therefore be provided by regular window ventilation or mechanical ventilation systems.
Leaks in the building envelope not only cause heat loss but can also result in serious structural damage, as warm indoor air carries moisture into the building fabric, where it can condense. This creates a risk of condensation and mould growth.
Benefits of an airtight building envelope
A properly installed airtight building envelope offers numerous benefits:
- Maintaining energy efficiency
- Protection against moisture damage caused by air movement
- Prevention of draughts
- Improved indoor air quality
- Better sound insulation
- Reliable operation of ventilation systems
- A prerequisite for fire protection concepts using gaseous extinguishing agents
Airtightness in new and existing buildings
Airtightness is an important quality criterion both for new buildings and for energy-efficient refurbishment of existing properties. A carefully designed and installed airtight layer helps save energy and prevent structural damage caused by convective moisture transport over the long term.
Conclusion
Airtightness is fundamental to energy-efficient, durable buildings. It helps maintain energy efficiency, protects the structure, improves indoor comfort and creates the conditions for modern building services to function optimally. Airtightness is verified by means of a BlowerDoor test.
Frequently asked questions about airtightness
What does airtightness mean in a building?
Airtightness means that the building envelope prevents uncontrolled airflow through joints, connections and other gaps. It is an important prerequisite for energy-efficient, durable buildings. An airtight envelope reduces heat loss, protects the structure from moisture damage and contributes to indoor comfort.
What problems can leaks in the building envelope cause?
Leaks can lead to additional heat loss and unwanted airflow. If warm, moist indoor air passes through gaps into colder parts of the structure, moisture may condense there. Over time, this can damage building components.
How can you check whether a building is sufficiently airtight?
A building's airtightness is checked using a BlowerDoor test. The test measures the air permeability of the building envelope under defined test conditions. Existing leaks can also be located so that weak points can be identified precisely.