What is an Escape Route Pressurization System and Why is it Necessary?

In a fire, the greatest threat is often not the flames themselves, but the smoke. Smoke obstructs visibility, hindering evacuation, and can be fatal if inhaled. For this very reason, escape route pressurization systems aim to isolate escape stairwells, fire safety lobbies, and elevator shafts from the rest of the building in terms of smoke.

The system creates a positive pressure in the escape space by pumping clean air into it in a controlled manner. Thanks to this pressure difference, smoke cannot enter the escape route through doorways or open doors; people evacuating and firefighters responding inside can move in a smoke-free, safe space.

Pressurization is not a 'install and forget' system. Fans, dampers, sensors, and backup power supplies working together at the correct pressure and airflow will prevent the system from providing the expected protection on a fire day. Therefore, periodic inspections are a far more critical layer of assurance than the mere existence of the system.

• Purpose: To protect escape staircases and safety halls from smoke ingress.
• Method: To create positive pressure in the escape volume relative to adjacent compartments.
• Result: a smoke-free, safe escape route for evacuation and fire intervention.

The Difference Between Pressurization and Smoke Extraction

These two systems are often confused, but their operating principles are opposite and they maintain different volumes. Smoke extraction (smoke control) systems aim to remove smoke from the area where it is generated—for example, a parking lot, atrium, or production area. A pressurization system, on the other hand, does not extract smoke; it prevents smoke from entering the escape route in the first place by pumping air into it.

In short: smoke extraction works on the principle of 'expelling smoke', while pressurization works on the principle of 'pushing smoke in'. One draws/expels smoke with negative pressure, the other pushes it out with positive pressure. Both can exist together in a building and often complement each other, but they are separate systems; the presence of one does not replace the other.

It is important to emphasize this distinction: the presence of a smoke extraction system in a building does not mean that escape stairwell pressurization is controlled. The two systems are designed separately, tested separately, and reported separately.

• Smoke extraction: removes smoke from the area where it is located (negative control)
• Pressurization: prevents smoke from entering by forcing air into the escape route (positive pressure)
• The two systems complement each other, but one cannot replace the other.
• Each system is designed separately, tested separately, and reported on separately.

Legal Basis: BYKHY and Performance Criteria

The legal basis for escape route pressurization is the Regulation on Fire Protection of Buildings (BYKHY; Official Gazette dated 19.12.2007 and numbered 26735). The regulation mandates the pressurization of escape staircases in buildings exceeding 51.50 m in height.

BYKHY defines the performance that the system must provide directly with numerical criteria. When the doors are closed, the pressure difference between the escape volume and the adjacent volume must be at least 50 Pa; however, the pressure should not prevent a person from opening the escape door, meaning the door opening force should not exceed 110 N. When the door is opened during escape, the average air velocity passing through the door opening must be at least 1 m/s.

These criteria represent a design that must be balanced: the pressure must be high enough to keep the smoke out, and low enough not to prevent the door from being opened manually. Periodic inspection verifies whether this balance is still achieved in the field by measuring it. Periodic testing and inspection of the system within this scope is mandatory according to BYKHY (Turkish Standards Institution for Safety and Quality).

• Basis: BYKHY, RG 19.12.2007 / 26735
• Obligation threshold: buildings with a height exceeding 51.50 m.
• Pressure difference at the closed door: at least 50 Pa
• Door opening force: maximum 110 N
• Average air speed with an open door: at least 1 m/s

System Components: Fan, Damper, Sensor

The performance of the pressurization system is the result of all its components working correctly together, not individual components. The main supply fan provides the necessary airflow to the escape space; ducts and vents distribute this air throughout the stairwell. Pressure control (overpressure relief) dampers keep the pressure in the space within the target range, preventing both insufficient pressure and pressure that would prevent doors from opening.

Pressure sensors and the control panel are the brain of the system: they measure the instantaneous pressure in the escape space and manage the dampers and fan speed accordingly. Thanks to integration with the fire detection system, the system automatically activates in case of an alarm. The correct positioning and response times of the dampers, actuators, and sensors are all aspects that must be individually monitored during control.

This component chain encompasses both mechanical (fan, duct, damper, airflow) and electrical (control panel, sensor, actuator, fire alarm integration) disciplines. AES Innovation's approach to this service is based precisely on this mechanical-electrical intersection.

• Supply fan and air distribution ducts
• Pressure control / overpressure relief dampers and actuators
• Pressure sensors and automatic control panel
• Integration with fire detection system (automatic activation)

Measurements taken during the inspection: Pressure, Air Velocity, Gate Force.

The essence of periodic inspection is to verify, through measurement, whether the system actually meets the design criteria in the field. These measurements, carried out with calibrated devices, are evaluated according to performance targets based on BYKHY and TS EN 12101-6.

Measurements are repeated under different scenarios: pressure difference with doors closed, air velocity with selected doors open, and door opening force in all scenarios. Meeting one criterion does not mean the other can be disregarded; for example, if the door force exceeds 110 N while maintaining a pressure of 50 Pa, this indicates that the system is unsuitable in another respect.

Measurement results are reported in comparison with the criteria; if a discrepancy is detected, the cause (fan flow rate, damper adjustment, leakage, sensor calibration, etc.) is identified and corrective recommendations are provided.

• Pressure difference measurement in a closed door (target ≥ 50 Pa)
• Average air velocity measurement with an open door (target ≥ 1 m/s)
• Door opening force measurement (target ≤ 110 N)
• Observation of damper response, fan flow rate, and sensor behavior.
• Comparative analysis of results and causes of nonconformity using the criterion.

Electrical Side: Backup Power and Generator Automatic Switching

The pressurization system is most likely to be affected by a power outage at the moment it is most needed – during a fire. Therefore, it is critical that the system is powered by a backup power source (usually a diesel generator) and can automatically switch to this source if the grid fails. No matter how good the fan is, its protection is lost if the power goes out.

Therefore, the inspection verifies not only the fan's operation but also the activation of the automatic transfer switch (ATS), the stable operation of the generator under load, and the uninterrupted performance of the system. The integration of fire alarm and pressurization is also part of this electrical verification.

The fan, damper, and pressure system constitute the mechanical side; the backup power, generator automatic switching, and alarm integration form the electrical side. AES Innovation's team profile is designed to work precisely at the intersection of these two disciplines; the system is meaningfully validated when mechanical and electrical engineering are considered together, rather than as a single discipline.

• Verification of automatic switching to backup power in case of a power outage.
• Checking the response of the automatic transfer switch (ATS).
• Stable operation of the diesel generator under load.
• Testing the integration of fire alarm and pressurization.

Testing Periods: Weekly, Monthly, Yearly

TS EN 12101-6-based good practice stipulates testing the pressurization system at varying frequencies and depths. Frequent and simple tests ensure the equipment is 'operational'; infrequent and comprehensive tests ensure the system as a whole meets the performance criteria.

This phased approach ensures the system remains ready throughout the year. Weekly and monthly tests are routine checks that can be carried out by the facility operator; however, the full annual system performance test, which requires measurement and evaluation, should be performed by a qualified engineer.

• Weekly: fan operation test
• Monthly: automatic switch-on test to backup power supply (at least 1 hour on diesel generator)
• Annual: full system performance test (pressure, air speed, gate force measurements)

Who should conduct the inspection, and what should be reported?

Annual performance checks of the pressurization system must be carried out by qualified engineers capable of evaluating both the mechanical (fan, airflow, pressure, damper) and electrical (backup power, generator switching, alarm integration) aspects. It is essential that measurements are taken with calibrated devices and that the results are interpreted according to the BYKHY and TS EN 12101-6 criteria.

AES Innovation provides this service as an engineering assessment measuring the integrity of the system at the mechanical-electrical junction, resulting in a technical report prepared by a qualified mechanical/electrical engineer. This report includes a comparison of the measured values with the criteria, identified nonconformities, and corrective recommendations.

This is an engineering technical assessment report; it is not an accredited inspection report, certificate, or conformity document. Its purpose is to provide the facility owner and relevant authorities with an unbiased and measurable demonstration of the system's performance.

• Evaluated by: a qualified mechanical and/or electrical engineer
• Method: Measurement with calibrated devices + comparison with criteria.
• Output: Authorized engineer's technical report (measurements, discrepancies, recommendations)
• Scope: engineering assessment — not an accredited inspection/certification.

Summary and Information Note

Escape route pressurization systems are mandatory in buildings exceeding 51.50 m in height and provide protection not only upon installation but also through regular testing. Meeting criteria such as a pressure difference of ≥50 Pa at the closed door, a door force of ≤110 N, and an air velocity of ≥1 m/s at the open door, as well as ensuring the system switches seamlessly to backup power in the event of a mains outage, can only be verified through measurement and observation on-site.

AES Innovation conducts this assessment using an approach that combines mechanical and electrical disciplines, resulting in an authorized engineering technical report. It is important to emphasize that the system has a protective layer that is different from and independent of smoke extraction systems.

Information note: This page is for general informational purposes only and does not substitute for engineering advice or legal opinion. The regulations and performance criteria cited are summaries only; the exact requirements for each building may vary depending on the building characteristics and current applicable legislation. Binding assessment is based on site measurements by a qualified engineer and the current text of the relevant legislation.

Related Services

• Smoke Evacuation
• Fire Installation
• Fire Damper

Frequently Asked Questions

In which buildings is a pressurization system mandatory?

According to the Regulation on Fire Protection of Buildings (BYKHY), pressurization of escape stairwells is mandatory in buildings exceeding 51.50 m in height. In these buildings, periodic inspection and testing of the system are as much a requirement as its installation.

Are pressurization and smoke extraction systems the same thing?

No. A smoke extraction system removes smoke from the area where it is located; a pressurization system prevents smoke from entering the escape route by pumping air into it. These are two systems that operate on different principles, are designed separately, and are tested separately; one is not a substitute for the other.

What values are measured during the control?

Three main criteria are measured: pressure difference at closed door (minimum 50 Pa), door opening force (maximum 110 N), and average air velocity at open door (minimum 1 m/s). Additionally, fan flow rate, damper response, sensor behavior, and automatic switching to backup power are observed.

How often should the system be tested?

According to TS EN 12101-6 best practice, fans are run weekly, automatic switching to backup power is tested at least once a month (at least 1 hour on the diesel generator), and a full system performance test is carried out annually. While weekly/monthly tests can be conducted by the operator, the annual performance test requires a qualified engineer.

Why is electrical backup power part of the control system?

The city power grid may be interrupted during a fire. For the system to continue operating at that moment, it needs to automatically switch to a backup power source (usually a diesel generator). Therefore, the activation of the automatic transfer switch, the stable operation of the generator under load, and the integration of the fire alarm are also verified — this requires an evaluation of the system at the machine-electrical junction.

Does AES Innovation provide certification for this service?

No. As part of this service, AES Innovation prepares a technical report by an authorized mechanical/electrical engineer; this is a measurement-based engineering assessment and is not an accredited inspection report, certificate, or conformity document. The report includes measured values, comparison with criteria, nonconformities, and corrective recommendations.