What is a standalone smoke detector (DAAF)?
The standalone smoke detector (DAAF) is a device that detects smoke and triggers a local audible alarm, without connection to a control panel or signalling board. It operates independently, powered by battery, without wiring to a monitoring station or transmission to a fire service. This device was designed for residential use: it is the device whose mandatory installation in dwellings has, according to authorities, reduced fire deaths in Brussels in 2025. In Belgium, only one person in two currently has a smoke detector at home. The DAAF was never designed to cover an entire professional building, workshop, warehouse or establishment open to the public.
What is a professional fire detection system according to NBN S21-100?
A fire detection system compliant with Belgian standard NBN S21-100-1 is a centralised installation: detectors connected by wiring to a signalling board, backup power supply, identified detection zones, and often alarm transmission. Its design follows NBN S21-100-1, its maintenance and periodic inspections follow NBN S21-100-2. Installed equipment must bear BOSEC certification, and the installer must be able to demonstrate their competence. The ANPI organisation acts as a technical reference in this sector. This type of system enables early detection, precise location of the fire source and generalised alarm, suitable for buildings occupied by staff, residents or public who do not necessarily know the premises.
What are the concrete differences between a DAAF and a fire detection system?
A DAAF and a professional detection system do not meet the same need, nor the same reliability requirement. The following table summarises the essential differences between the two devices.
| Criterion | Consumer-grade DAAF | Fire detection system per NBN S21-100 |
|---|---|---|
| Power supply | Standalone battery | Mains power + backup |
| Wiring | None, isolated device | Wired to signalling board |
| Detection | Local, single room | By zones, throughout building |
| Alarm transmission | None | Possible to fire service |
| Maintenance | Not regulated | NBN S21-100-2, periodic inspections |
| Certification | Generic CE marking | BOSEC, qualified installer |
| Design | No study required | Study per NBN S21-100-1 |
This design difference explains why a DAAF cannot substitute for a fire detection system when regulations require generalised detection.
In which cases is a DAAF tolerated in a professional building?
A DAAF is only tolerated in limited ancillary spaces, never as a substitute for a fire detection obligation imposed elsewhere. This is the typical case of a small isolated office, a secondary technical room or a service dwelling integrated into a main building, when these spaces are not covered by the generalised detection obligation set by the Royal Decree of 7 July 1994 or by the site's specific operating conditions. The Code on Well-being at Work (Book III, Title 3) requires employers to conduct a fire risk analysis in the workplace: depending on size and activity, this analysis may conclude that a DAAF is sufficient in a very restricted space, without night staff or hazardous storage. This tolerance remains the exception, never the default rule.
What does Belgian regulation say about professional fire detection obligations?
The Royal Decree of 7 July 1994 establishing basic standards for fire and explosion prevention classifies buildings as low, medium and high, and imposes detection and alarm equipment requirements according to this height and the purpose of the premises. The design of these installations must follow standard NBN S21-100-1, their maintenance and periodic inspections NBN S21-100-2. The territorially competent emergency zone (hulpverleningszone) provides an opinion on the file and carries out on-site inspections: it validates, or refuses, the installation's compliance with the building's operating conditions. The environmental or planning permit may also refer to these requirements. None of these texts recognise the DAAF as equivalent to a compliant fire detection system.
What risks does an operator face who replaces mandatory detection with DAAFs?
Replacing mandatory fire detection with simple DAAFs exposes the operator to refusal of approval from the emergency zone, a condition often linked to maintaining the building's operating authorisation. In the event of a fire, the absence of a system compliant with NBN S21-100 may be considered a breach in the analysis of the operator's or employer's responsibilities, including criminal liability, under the Code on Well-being at Work. The fire insurer may also invoke the installation's non-compliance to dispute coverage of the loss. It should be noted that in Belgium, approximately 10,000 fires occur each year in buildings, an order of magnitude reported by UGent in the absence of systematic data collection, and that 70% of companies affected by a major fire never recover.