Refuge Areas and Safe Havens

Refuge Area Concepts

Refuge areas provide temporary safe locations within tall buildings for occupants unable to immediately evacuate during emergencies. These spaces—also called areas of refuge, safe havens, or evacuation assistance spaces—protect occupants from fire, smoke, and heat while awaiting rescue or until conditions allow continued evacuation.

Building codes require refuge areas in specific circumstances:

High-rise buildings (> 75 feet above fire department access)
Buildings lacking adequate egress capacity for all occupants
Areas serving occupants with mobility impairments
Locations designated for firefighter staging operations

Code Requirements

International Building Code (IBC)

IBC establishes refuge area provisions:

Location Requirements:

Located immediately adjacent to exit enclosures (stairs)
Accessible without passing through non-protected spaces
Maximum travel distance same as for exits
Minimum of two refuge areas per floor (egress independence)

Size Requirements:

Minimum area: 30 inches × 48 inches per occupant wheelchair space
Minimum two wheelchair spaces per refuge area
Additional space for ambulatory occupants if area serves general refuge function
Clear floor space complying with accessibility standards

Separation Requirements:

Separated from remainder of floor by smoke barrier (minimum 1-hour fire-resistance rating)
Protected from exposure through exterior walls
Protected from vertical fire spread through floor/ceiling assemblies

Communication:

Two-way communication system to fire command center
Visual and tactile identification signage
Emergency lighting per life safety code

NFPA 101 (Life Safety Code)

NFPA 101 provides additional criteria:

Occupant Load Calculation: Refuge area sized for:

Occupants served by that area
Typically calculated as percentage of floor occupant load (15-20% for mobility-impaired)
All occupants if area serves as general safe haven

Environmental Control: Maintain tenable conditions:

Smoke-free environment through pressurization
Thermal conditions within survivable limits
Adequate oxygen concentration through ventilation

Duration: Designed for occupancy duration until:

Rescue by firefighters
Fire suppression enables continued evacuation
Typically 30-60 minutes minimum design period

Pressurization Requirements

Refuge areas require positive pressure relative to fire floor to prevent smoke infiltration.

Minimum Pressure Differentials

Design Pressures:

Minimum: 0.05 in. w.c. (25 Pa) across smoke barrier
Typical design target: 0.10-0.15 in. w.c. (50-75 Pa)
Maximum: 0.35 in. w.c. (175 Pa) to limit door opening forces

These values align with smoke control system requirements per NFPA 92.

Pressure Hierarchy

In integrated systems, pressure staging creates multiple protection layers:

Four-Zone System Example:

Exit stair: 0.25 in. w.c. (highest pressure)
Refuge area: 0.15 in. w.c.
Protected corridor: 0.05 in. w.c.
Fire floor: 0.00 in. w.c. (reference)

Each boundary maintains minimum differential while limiting maximum for door operation.

Stack Effect Considerations

Tall building stack effect affects refuge area pressurization:

Winter Conditions (upward stack effect):

Lower floors: stack effect creates negative pressure
Refuge area system must overcome stack effect plus provide design differential
Upper floors: stack effect assists pressurization
Risk of over-pressurization requiring pressure relief

Summer Conditions (downward or minimal stack effect):

More uniform pressure distribution
Upper floors may require increased pressurization
Generally less challenging than winter conditions

Design Approach:

Calculate stack effect for design outdoor temperature
Size system for worst-case floor and conditions
Provide floor-by-floor pressure balancing
Install relief dampers where over-pressurization anticipated

Air Supply Systems

Supply Airflow Calculation

Required supply airflow maintains design pressure against all leakage paths:

$$Q_{supply} = \sum \left(A_i \times 2610 \times \sqrt{\Delta P_i}\right)$$

Where:

$Q_{supply}$ = required supply airflow (cfm)
$A_i$ = effective leakage area of opening i (ft²)
$\Delta P_i$ = pressure differential across opening i (in. w.c.)

Leakage Paths:

Doors to fire floor (primary leakage)
Doors to exit stair (if pressure staging employed)
Construction leakage through smoke barrier
Ventilation or relief air openings

Example Calculation: Refuge area (elevator lobby) with:

1 door to fire floor corridor (0.15 ft² leakage)
1 door to exit stair (0.15 ft² leakage)
Construction leakage (0.05 ft² estimated)
Design pressure: 0.10 in. w.c. to corridor, 0.05 in. w.c. to stair

$$Q_{supply} = (0.15 \times 2610 \times \sqrt{0.10}) + (0.15 \times 2610 \times \sqrt{0.05}) + (0.05 \times 2610 \times \sqrt{0.10})$$ $$Q_{supply} = 124 + 88 + 41 = 253 \text{ cfm (all doors closed)}$$

Open Door Flow

When doors open during refuge area use:

$$Q_{open_door} = C_d \times A_{open} \times 4005 \times \sqrt{\Delta P}$$

Where:

$Q_{open_door}$ = flow through open doorway (cfm)
$C_d$ = discharge coefficient (0.65 typical)
$A_{open}$ = open door area (ft², typically 21 ft² for 3’ × 7’ door)
$\Delta P$ = pressure differential (in. w.c.)

For single door open at 0.10 in. w.c.:

$$Q_{open_door} = 0.65 \times 21 \times 4005 \times \sqrt{0.10} = 17,300 \text{ cfm}$$

This flow rate 68 times larger than closed-door leakage. Supply system must maintain adequate airflow with design number of doors open (typically one door).

Supply System Configurations

Dedicated Supply Fan:

Independent fan serving refuge area only
Located in protected space or remote location
Sized for maximum required airflow
Variable speed control responding to pressure differential

Shared Supply with Zone Dampers:

Common supply fan serving multiple refuge areas
Zone dampers control airflow to each area
Pressure-independent dampers maintain setpoint
Central monitoring of all zones

Integration with Stairwell Pressurization:

Refuge areas adjacent to stairs share pressurization air
Transfer grilles or relief dampers allow airflow from stair to refuge area
Simpler system but less independent control
Requires coordinated pressure analysis

Makeup Air Sources

Air supplied to refuge area originates from:

100% Outdoor Air: Dedicated outdoor air intake:

Ensures fresh, smoke-free air supply
Located to avoid smoke contamination
Protected from wind effects
Provides guaranteed air quality

Filtered Recirculated Air: Return air from non-fire floors:

Requires smoke detection to prevent smoke recirculation
Automatic dampers isolate contaminated zones
HEPA filtration for smoke particle removal
Cost effective but requires careful controls

Transfer from Protected Zones: Air from adjacent pressurized spaces:

Stairwell pressurization air transfers to refuge area
Reduced total airflow requirement
Simplified system architecture
Dependent on maintaining stair pressurization

Elevator Lobbies as Refuge Areas

Protected elevator lobbies serve dual functions:

Elevator smoke protection during normal firefighter access
Refuge areas for occupants during emergencies

Configuration Requirements

Separation: 1-hour fire-resistance-rated smoke barrier separating lobby from:

Floor corridors and occupied spaces
Elevator shafts (except at elevator doors)
Other non-protected spaces

Access: Direct access from:

Floor corridors through self-closing smoke barrier doors
Exit stairs through self-closing doors
Minimum two means of egress from lobby

Size: Adequate for:

Elevator service to floor
Refuge area occupants (minimum two wheelchairs)
Firefighting operations staging
Typical size: 150-300 ft² depending on building size

Pressurization Design

Three-zone pressurization system typical:

Zone 1 - Exit Stair (highest pressure):

Design pressure: 0.20-0.25 in. w.c. relative to fire floor
Primary protected egress path
Independent pressurization system

Zone 2 - Elevator Lobby (intermediate pressure):

Design pressure: 0.10-0.15 in. w.c. relative to fire floor
Refuge area and firefighter staging
Dedicated or shared pressurization

Zone 3 - Floor Corridor (fire floor, lowest pressure):

Reference pressure (0.00 in. w.c.)
May have negative pressure if smoke exhaust employed
Contains fire and smoke

Differential Across Boundaries:

Stair to lobby: 0.05-0.10 in. w.c.
Lobby to corridor: 0.10-0.15 in. w.c.
Stair to corridor: 0.15-0.25 in. w.c. (sum of above)

Door Opening Force Management

Pressure staging reduces door opening forces:

Single Barrier: Stair door opens directly to fire floor:

Full pressure differential across single door
At 0.25 in. w.c., door opening force ~50 lbf (exceeds 30 lbf limit)
Requires pressure limitation or force-reduction measures

Pressure Staging through Lobby: Two doors in series:

Stair to lobby door: 0.10 in. w.c. differential, ~20 lbf opening force
Lobby to corridor door: 0.15 in. w.c. differential, ~30 lbf opening force
Each door within code limits
Enables higher total protection level

Integration with Elevator Operations

Normal Operations: Elevator recall on fire alarm:

Elevators recalled to designated landing
Lobby maintains normal environment
Pressurization system may activate proactively

Fire Service Operations: Firefighter elevator use:

Lobby pressurized to exclude smoke
Adequate airflow to accommodate firefighter door traffic
Communication system to fire command center
Emergency lighting and signage

Refuge Function: Occupants use lobby as safe haven:

Pressurization maintains smoke-free environment
Two-way communication enables status updates
Clear space for wheelchairs and occupants
Visual confirmation of protected status

Ventilation and Air Quality

Minimum Ventilation Rates

Refuge areas require adequate outdoor air for occupants:

ASHRAE 62.1 Basis: Minimum outdoor air per person:

Standard occupancy: 5-7.5 cfm/person
Refuge area with potential stress: 15-20 cfm/person recommended

Occupant Load Calculation:

Design occupancy: maximum anticipated refuge area use
Mobility-impaired positions: minimum two
Additional occupants: based on area size and accessibility
Typical design: 10-30 occupants

Example: 20-person refuge area at 15 cfm/person: $$Q_{ventilation} = 20 \times 15 = 300 \text{ cfm}$$

This ventilation requirement typically smaller than pressurization airflow requirement.

Thermal Control

Maintaining acceptable temperatures in refuge areas:

Heat Gain Sources:

Solar radiation through exterior walls/windows
Heat transfer from fire floor (if adjacent)
Occupant metabolic heat (250-300 Btu/hr per person)
Lighting and equipment

Temperature Control Strategies:

Tempered supply air (55-65°F) to offset heat gains
Radiant cooling for perimeter heat gains
Thermal insulation in smoke barrier construction
Emergency cooling capacity in extreme conditions

Design Criteria:

Maximum temperature: 95°F for 30-minute duration
Preferred range: 65-85°F for occupant comfort
Account for reduced air change rates during emergency
Coordinate with fire scenario temperature analysis

Air Quality Monitoring

Oxygen Concentration: Ensure adequate oxygen for respiration:

Minimum: 19.5% O₂ (OSHA standard)
Normal atmosphere: 21% O₂
Outdoor air ventilation maintains acceptable levels
Monitor in sealed refuge areas with long duration occupancy

CO₂ Concentration: Indicator of ventilation adequacy:

Maximum: 5,000 ppm for emergency conditions
Preferred: < 1,000 ppm for extended occupancy
Ventilation rate prevents excessive accumulation

Smoke Detection: Continuous smoke monitoring:

Photoelectric or ionization detectors
Alarm on smoke detection indicating system failure
Automatic control response to increase pressurization
Visual and audible alarms in refuge area

Control and Monitoring Systems

Activation Sequences

Automatic Activation: Smoke control system activation triggers refuge area pressurization:

Fire alarm receives smoke detector signal
System identifies fire floor and zone
Refuge area pressurization activates on fire floor
Adjacent floor refuge areas may activate (design dependent)
Monitoring system confirms target pressures achieved

Manual Activation: Fire command center override:

Operator selects specific refuge areas to pressurize
Independent of automatic smoke detection
Allows response to non-fire emergencies
Requires trained personnel

Pressure Monitoring

Sensor Locations:

Differential pressure across each smoke barrier door
Reference to fire floor corridor
Reference to adjacent protected spaces (stairs)
Multiple sensors in large refuge areas

Monitoring Parameters:

Real-time pressure differential display
Trend logging for forensic analysis
Alarm on out-of-range conditions
Integration with building management system

Control Response:

Modulate supply fan speed to maintain target pressure
Adjust relief dampers to prevent over-pressurization
Alarm on inability to achieve target pressures
Automatic switchover to backup systems if available

Communication Systems

Two-Way Communication: Direct connection to fire command center:

Voice communication (intercom or telephone)
Visual indicators showing communication status
Located at wheelchair accessible height
Clearly marked and illuminated

Mass Notification: Broadcast system in refuge area:

Emergency voice/alarm communication system
Instructions to occupants
Status updates from incident commander
Coordination with building-wide emergency communication

Visual Displays: Information for occupants:

Illuminated signs identifying refuge area
Pressure status indicators (optional)
Exit route confirmation
Instructions for refuge area use

Design Integration Challenges

Multi-Floor Coordination

Tall buildings with refuge areas on each floor:

Simultaneous Activation: Fire scenarios may affect multiple floors:

Vertical fire spread to adjacent floors
Smoke migration through shafts
Multiple refuge areas activate simultaneously
System capacity for worst-case scenario

Phased Evacuation: Building evacuation strategy affects refuge area use:

Fire floor and adjacent floors evacuate first
Other floors shelter in place or use refuge areas
System must support varying occupancy patterns

Interaction with Building HVAC

Refuge area pressurization coordinates with normal HVAC:

Dual-Purpose Equipment: HVAC equipment serves normal and emergency functions:

Normal mode: ventilation and conditioning
Emergency mode: smoke control and pressurization
Sizing for larger of two requirements
Control system mode switching

Ductwork Sharing: Supply ductwork serves both functions:

Normal HVAC distribution to occupied spaces
Emergency pressurization air to refuge areas
Smoke dampers ensure proper isolation
Leakage requirements differ between modes

Maintenance and Testing

Periodic Testing: Regular verification of system performance:

Quarterly functional test of pressurization system
Annual pressure differential testing
Door opening force verification
Communication system testing

Maintenance Access: Refuge area equipment requires service access:

Fans, dampers, and controls in protected locations
Accessible without compromising protection
Adequate clearances for maintenance
Spare parts stocking for critical components

Training: Building staff and occupants require training:

Refuge area location and use
Communication system operation
Emergency procedures specific to refuge areas
Coordination with fire department operations

Refuge areas provide critical life safety functions in tall buildings where immediate evacuation may not be possible for all occupants. Proper pressurization design, adequate air supply, and reliable control systems ensure these spaces maintain tenable conditions during fire emergencies. Integration with overall smoke control systems, compliance with code requirements, and comprehensive commissioning create dependable safe havens when needed most.