Today’s buildings must meet high standards of energy performance and fire safety. On the one hand, air tightness limits heat loss and improves energy efficiency. On the other hand, fire compartmentalisation prevents the spread of flames and smoke. However, ventilation systems create openings in the building envelope. How can these two technical requirements be reconciled without compromising regulatory compliance ?
This question has become increasingly important in modern construction. Buildings are expected to consume less energy while maintaining high levels of safety for occupants. Architects and engineers must therefore integrate multiple technical constraints within the same design. Airtightness, ventilation and fire safety are not isolated considerations but interconnected elements that must function together within the building envelope.
Understanding airtightness in a building
Airtightness refers to a building’s ability to limit uncontrolled air infiltration through its envelope. It is generally measured by an airtightness test, often called a ‘blower door test’, which assesses the overall level of leakage.
This test places the building under pressure or vacuum conditions in order to detect air leaks. By measuring the air flow required to maintain a specific pressure difference, professionals can determine how well the building envelope performs. A lower leakage rate generally indicates better airtightness and therefore better energy performance.
Good airtightness allows you to :
- Reduce heat loss
- Improve thermal comfort
- Limit energy consumption
In addition, improved airtightness contributes to better indoor environmental quality. When uncontrolled air infiltration is reduced, ventilation systems can operate more efficiently and distribute fresh air more evenly throughout the building.
However, each technical penetration represents a potential point of leakage. Ducts, conduits and ventilation grilles must therefore be integrated with precision in order to avoid unwanted infiltration.
Thus, energy performance depends largely on the quality of the construction details. Even small gaps around installations or poorly sealed penetrations can significantly affect the overall airtightness level of a building.
The principle of fire compartmentalisation
Passive fire protection is based on dividing the building into compartments. Fire walls classified as EI30, EI60 or EI90 are designed to withstand fire for a specified period of time.
These classifications indicate the duration during which the wall maintains both its integrity and insulation capacity. During this period, the structure prevents flames, smoke and heat from spreading to adjacent compartments.
Compartmentalisation has two main objectives :
- To limit the spread of flames
- To slow down the spread of smoke
This strategy plays a crucial role in protecting occupants. By containing a fire within a specific zone, evacuation can take place more safely and emergency services have more time to intervene.
However, the effectiveness of these walls depends on their continuity. When an opening is created for ventilation, this continuity can be compromised. A standard grille that is not suitable can become a passageway for fire or smoke.
Therefore, any opening in a fire wall must be treated with an appropriate device. Properly designed systems ensure that the wall maintains its fire resistance performance even when technical penetrations are present.
Where does the difficulty lie ?
The difficulty arises when several technical requirements overlap. Indeed, a high-performance building must :
- Ensure adequate ventilation
- Maintain a sealed envelope
- Comply with fire resistance requirements
These objectives may seem contradictory. An opening promotes air circulation, but it can compromise airtightness. Similarly, a poorly integrated fire protection device can cause peripheral leaks.
In addition, construction projects often involve multiple stakeholders working on different technical systems. Without proper coordination, the installation of ventilation equipment or fire protection elements can create inconsistencies in the building envelope.
So, the question is not one of choosing between ventilation, airtightness or safety, but of coordinating these parameters from the design stage onwards.
Existing technical solutions
Several solutions are available to combine airtightness and fire protection. It is useful to analyse the various devices available on the European market in order to understand how they work, their certifications and their installation requirements. Specialised resources such as https://tei.lu/en/ present, for example, various systems related to fire dampers and intumescent devices used in passive protection.
These systems are designed specifically to address the challenges associated with ventilation openings in fire-resistant walls. Their performance is usually verified through laboratory testing and certification processes that ensure compliance with European standards.
Intumescent devices
Intumescent grilles or elements allow air to circulate under normal conditions. In the event of a significant rise in temperature, the material expands and blocks the opening. Compartmentalisation is then restored.
The expansion of the intumescent material occurs when it is exposed to high temperatures generated by fire. The material can increase several times its original volume, effectively sealing the opening and preventing the spread of flames and hot gases.
This type of device must be certified according to the applicable standards and installed in accordance with technical requirements. Correct positioning and proper anchoring are essential to ensure that the device performs as intended during a fire event.
Peripheral treatment of penetrations
Sealing does not depend solely on the product itself. The treatment of joints, fixings and interfaces with the wall is crucial.
Installation quality plays a major role in both airtightness and fire resistance. Sealants, collars or specific sealing systems are often used to ensure that the penetration remains airtight while preserving the fire resistance of the wall.
Precise installation allows :
- Limited air infiltration
- Fire continuity
- Avoidance of defects during inspections
Thus, overall performance depends on the entire system, not just a single component. A well-designed solution integrates both the fire protection device and the airtightness treatment around it.
Coordination between project stakeholders
Furthermore, early coordination between architects, HVAC engineers and fire safety specialists reduces the risk of incompatibility. An integrated solution from the design phase limits modifications at the end of the project.
During the planning stage, technical drawings and specifications should clearly indicate the location and type of penetrations. This allows each specialist to anticipate constraints and propose suitable solutions before construction begins.
This approach promotes greater technical and regulatory consistency. It also reduces delays and avoids costly adjustments during the final stages of the project.
Example of application in a residential building
In a recent apartment building, energy requirements dictate a high-performance envelope. At the same time, regulations require strict compartmentalisation between dwellings.
In this context, ventilation openings must be equipped with appropriate devices. These allow :
- Air to pass through during normal operation
- Automatic closure in the event of a fire
- Maintenance of the required fire resistance
Such installations illustrate how modern construction techniques integrate both energy efficiency and fire safety considerations. When properly designed and installed, these systems contribute to the overall reliability of the building envelope.
As a result, the building retains its energy performance while complying with safety regulations.
An increasingly common issue
With changing energy standards and urban densification, combining airtightness and fire protection is becoming a key challenge. Energy-efficient buildings require precise, documented technical solutions.
New regulations across Europe increasingly emphasise both energy performance and safety requirements. As a consequence, designers must ensure that technical installations do not undermine the integrity of fire-resistant structures or the airtightness of the building envelope.
It is therefore necessary to assess each wall penetration, each grille and each duct in terms of both requirements. A comprehensive approach helps to avoid non-compliance and ensure the safety of occupants.
Air tightness and fire protection have different but complementary objectives. The former aims to improve energy performance, while the latter aims to protect people and property.
However, their coexistence requires rigorous design and solutions adapted to the constraints of the project. By anticipating these challenges early on in the design phase, it is possible to effectively reconcile ventilation, thermal performance and fire compartmentalisation.
This issue illustrates the importance of a cross-disciplinary technical approach in the design of modern buildings.