Emergency Lighting Calculator

Emergency Lighting Design Guide for AS/NZS 2293.1

Emergency lighting is a life safety system that provides illumination on escape routes when the normal mains supply fails. In Australia and New Zealand, emergency lighting design, installation, and maintenance are governed by AS/NZS 2293.1 (design and installation) and AS/NZS 2293.2 (inspection and maintenance). The standard applies to all buildings required by the Building Code of Australia (BCA) to have emergency lighting, including commercial offices, retail premises, hospitals, aged care facilities, multi-storey residential buildings, and places of public assembly. This calculator helps you estimate the number of emergency luminaires required for a given floor area, the placement of illuminated exit signs, and the battery capacity needed to maintain the required light levels for the full 90 minute duration.

Key concepts

• Minimum illumination levels. AS/NZS 2293.1 requires a minimum of 0.2 lux on the floor along the centre line of escape routes, and 1 lux at changes of direction, intersections, stairways, and within 2 metres of exit doors. These levels must be achieved at the end of the rated battery duration (90 minutes), not just at initial switch-on when lumen output is highest.
• Maintained vs non-maintained luminaires. Maintained emergency luminaires operate continuously as part of the normal room lighting and switch to battery power during a mains failure. Non-maintained luminaires are off during normal operation and activate only when the supply fails. AS/NZS 2293.1 requires maintained luminaires in places of public entertainment such as cinemas, theatres, and concert venues.
• Battery duration and sizing. The minimum battery duration is 90 minutes for most occupancies. The battery must be sized to deliver the required lumen output for the full duration at end-of-life capacity (typically 80 percent of initial capacity after 4 years). Central battery systems and individual self-contained luminaires are both acceptable, with different trade-offs in maintenance and reliability.
• Exit sign requirements. Illuminated exit signs must be installed at every required exit and along escape routes so that at least one sign is visible from any point on the path of travel. Signs must comply with AS/NZS 2293.1 and the BCA for size, pictogram design (running man), colour (green and white), and mounting height. Photoluminescent signs are permitted only in specific low-risk occupancies.

Common scenarios

1. Multi-storey office building. A 10-storey office tower with open plan floors, fire stairs, and a basement car park. Emergency luminaires are required in all corridors, stairwells, lobbies, and the car park. Exit signs are placed at each stairwell entry, lift lobby, and floor exit. The fire stairs typically require higher illumination (1 lux minimum on treads) because occupants are moving on uneven surfaces. Self-contained luminaires with individual batteries are common for office fitouts because they avoid the cost of running dedicated wiring back to a central battery room.
2. Hospital or aged care facility. Healthcare buildings have extended duration requirements and higher illumination levels in patient care areas. Staff must be able to read medication labels and operate equipment during a power failure. Central battery systems with monitored circuits are preferred for reliability, and the testing regime under AS/NZS 2293.2 is more stringent due to the vulnerable occupant population.
3. Retail shopping centre. Large open floor plates with high ceilings and multiple exit paths. The challenge is achieving 0.2 lux across wide open areas where luminaire spacing must account for the ceiling height and beam spread. Exit sign placement must ensure visibility above shelving and display fixtures. Places of public entertainment within the centre (such as cinemas) require maintained emergency luminaires.