What is a supply air opening in SHEV systems?
Supply air openings are an integral part of every SHEVS. In the event of a fire, they enable the targeted supply of fresh air from outside into the building. Without this air flow, smoke cannot be dissipated effectively as there is no necessary pressure equalization.
Core functions of the supply air opening:
- Generation of a directed air flow
- Support of the thermal lift
- Improving visibility
- Ensuring low-smoke escape routes
- Effective operation of the SHEVS
Legal basis and technical requirements
The installation and operation of supply air openings is regulated by various regulations:
- DIN 18232 (smoke and heat control)
- Model building regulations (MBO) and state building regulations
- M-HHR, M-LüAR, VdS guidelines
- Workplace Ordinance (ArbStättV) depending on use
Minimum technical requirements for supply air openings
For a supply air opening to function reliably in an emergency, it must meet specific technical requirements. The area of the supply air opening must be at least 50 percent of the exhaust air area to ensure an effective air flow.
It is also important that the openings are positioned close to the floor, for example by installing louvre windows or similar construction elements. The control can be either automatic or manual - the decisive factor is that the opening is reliably activated in the event of a fire.
Special requirements in high-rise buildings
High-rise buildings with a floor height of over 22 meters are subject to special fire protection requirements. Natural supply air openings are generally not sufficient here to ensure safe and effective smoke extraction.
Motor-controlled openings or mechanical supply air systems are therefore required. These systems enable targeted control of the air supply - both floor-by-floor and pressure-regulated. A connection to stairwell pressurization systems (RDA) is mandatory. In addition, the air routing must be designed in such a way that it functions reliably even when fire compartments are formed and prevents smoke from spreading.
Manual air intake by the fire department
Automatic air supply systems are not available in every building. In such cases, the fire department takes over the manual creation of the fresh air supply. For this purpose, firefighters open doors, windows or special flaps in the lower part of the building.
In addition, electric fans can be used to increase the air flow and support effective smoke extraction. Precise coordination with the exhaust air openings is essential here. Uncontrolled air supply can pose considerable risks - including the ignition of smoke gases or the unwanted spread of smoke to other parts of the building.
FAQ
What happens if there is no supply air opening?
Is automatic opening mandatory?
Who is responsible for tuning the supply air?
Is there a minimum size for supply air openings?