Refuge Area Calculator
Refuge Area Calculator (NBC 2016) — quick estimate
Refuge areas drive the core and the upper-floor plate in high-rise design. Get an indicative refuge area from the occupant load — based on the NBC 2016 Part 4 basis — before you lock the floor plate.
Your floor
Occupant-load factors are indicative — NBC assigns the factor by occupancy. Refuge-area provision and the height trigger are set by NBC 2016 Part 4 and the State fire rules.
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Assumptions & formula
Formula: occupant load = floor plate ÷ occupant-load factor. Refuge area = greater of (occupant load × 0.3 m²) and a 15 m² minimum.
- 0.3 m²/person and 15 m² minimum are the commonly-cited NBC 2016 Part 4 basis for refuge area — verify against the current edition for your occupancy.
- Height trigger: refuge areas are generally required at and above 24 m height — confirm the exact trigger and spacing for your building.
- Occupant-load factors shown are indicative; NBC assigns the factor by occupancy classification.
Verify: refuge-area rules, occupant-load factors and the height trigger are occupancy-specific and set by NBC 2016 Part 4 and the State fire rules. Confirm every value with a licensed fire engineer.
Indicative estimate only — not a binding design. Refuge area is governed by NBC 2016 Part 4, the occupancy classification and the local fire authority.
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How this calculator works — and where it stops
What it calculates
An indicative refuge area for one floor of a high-rise building, from the floor plate and the occupancy's occupant load factor, with the minimum area applied.
Inputs
- Floor plate area in m² (200 to 5,000)
- Occupancy — business or office (about 10 m² per person), mercantile or retail (about 3), assembly (about 1.5) or residential (about 12.5)
- Building height — below 24 m, or 24 m and above
Method
- Occupant load = floor plate ÷ the occupant load factor for the occupancy, rounded up to a whole person.
- Refuge area = occupant load × 0.3 m² per person.
- Where that figure is below 15 m², the 15 m² minimum is applied instead.
- Flags applicability by height: at 24 m and above refuge area applies under NBC 2016 Part 4; below 24 m it may not be required.
Assumptions
- The occupant load factors are common planning values for each occupancy group; the table in the governing code decides the figure for a specific building.
- 0.3 m² per person and the 15 m² minimum follow the NBC 2016 Part 4 pattern the tool is built on.
- The whole floor plate is treated as occupiable area.
Limitations
- The refuge-floor interval, its position relative to the staircases, fire separation, ventilation and fire-service access are not checked.
- Mixed occupancies on one floor are not modelled.
- The National Building Code 2016 was replaced by the National Building Construction Standards 2026 during 2026 — confirm with the approving authority which applies to the building before relying on the figure.
Worked example
Produced by running this calculator with the inputs below.
Inputs
- Floor plate: 1,500 m²
- Occupancy: business or office (10 m² per person)
- Height: 24 m and above
Working
- Occupant load = 1,500 ÷ 10 = 150 people
- Refuge area = 150 × 0.3 = 45 m²
- 45 m² is above the 15 m² minimum, so the minimum does not apply
Result. About 45 m² of refuge area for the floor. The same floor plate as assembly space (1.5 m² per person) gives 1,000 people and 300 m²; a 400 m² office floor gives 12 m², so the 15 m² minimum applies.
How engineers use the result
To reserve refuge area in the plan at concept stage, and to check whether a floor the architect has offered is large enough before the fire scheme is drawn.
When a professional design must replace it
Before the fire scheme is submitted: the refuge area, its location and its separation are fixed from the code that applies to the building's approval and checked against the architectural plans.
Got your number — what next?
A calculator gives you a first figure. These take it further.
The work itself
Read before you specify
The terms behind it
Delivered work with this scope
- Fire Safety at the Indian Army's Largest Tankage Project— Indian Army
- Operational Excellence for a Logistics Major— Nahar Logistics