Self-contained emergency lighting unit (BAES)

The BAES (Autonomous Emergency Lighting Unit) is a light fixture with an integrated battery that takes over in the event of a power outage to guide occupants to evacuation and secure hazardous areas. In France, it is used in public access buildings (ERP/ERT) and most commercial buildings, in addition to other fire safety systems. It is available in evacuation versions (exit pictograms), ambient/anti-panic versions (diffuse lighting of a specific area), or high-performance versions for specific premises. Recent models are LED, with a minimum battery life of approximately one hour and often include an Integrated Automatic Testing System (SATI) for periodic self-checks.

BAES: definition and essential components

A BAES (Emergency Response Unit) includes:

- a mains power supply and a battery (NiMH/LiFePO₄) which takes over automatically in the absence of voltage;

- an LED source (low consumption, long lifespan);

- a suitable optics (evacuation beam directed to the ground, wide environment);

- a standardized pictogram (arrow, "exit") for the evacuation version;

- a permanent mode (on when mains power is present) or a non-permanent mode (only lights up as a backup) depending on the needs;

- possibly a SATI for monthly/annual testing (operation + autonomy) and fault log.

Typical placement : above exits, at changes of direction, at the bottom/top of staircases, at circulation intersections, near first aid stations and firefighting equipment. The objective is to ensure a continuous minimum level of lighting along evacuation routes and in areas open to the public.

Advantages, limitations and points of attention of emergency lighting systems

Interests

• Personal safety: immediate identification of exits, limiting panic during a power outage/fire.
• Compliance: meets regulatory requirements (ERP/ERT), facilitates commission visits.
• Operation: durable LED versions, SATI to automate testing and improve traceability.

Boundaries

• Limited battery life: depends on battery status and ambient temperature.
• Mandatory maintenance (cleaning, testing, battery/pictogram replacement).
• Installation is sometimes constrained (height, aesthetics, aggressive environment).

Points to consider

• Typology: choose evacuation (pictograms) on the pathways and atmosphere in large volumes (anti-panic).
• Mode: permanent if required/sensitive location, not permanent elsewhere to save money.
• SATI: favour blocks with self-tests (monthly/annual) and fault reporting to technical room/BMS.
• Batteries: check lifespan and replacement procedure; record in a log.
• Installation & signage: height/visibility of pictograms, consistency of arrows, avoid visual obstructions (signs, vegetation).
• Environment: reinforced IP/stainless steel versions for parking lots, kitchens, wet areas; ATEX compatibility if required.
• Testing: set up a test schedule (monthly function, annual autonomy) and track interventions.

Anecdote — “The reassuring pictograms of Saint-Ouen”

In Saint-Ouen, a renovated office building experienced chaotic test evacuations: some aging, non-permanent emergency lighting units, contradictory pictograms, and no fire alarm system. The upgrade replaced the old units with LED emergency lighting units equipped with fire alarm systems, realigned the arrow directions, added panic bars in the atrium, and connected the fault reporting system to the building management system. During the following drill, the circulation routes remained clear, the stairwells well-lit, and the evacuation proceeded without hesitation. The building manager concluded: "We didn't just replace the units, we lit the way."