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G H
L C O N S U L T A N T S
L T D
Evacuation – Time To Go
BOABC – May 27, 2014
PresentersFrankie Victor, EngL, BCQ
Jun H. Kim, BASc, EIT
GHLCONSULTANTS LTDBuilding Codes and Fire Science
950 – 409 Granville StreetVancouver, BC V6C 1T2
Phone 604 689 4449Fax 604 689 4419
www.ghl.ca1
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G H L C O N S U L T A N T S
L T D
Copyright and Limitations
This presentation is conceptual and for educational
purposes only. GHL takes no responsibility for applicationof any concepts or interpretations in this presentation to
specific projects unless specifically retained for that project.
This presentation is intended to be presented by GHL andthese slides must not be considered complete or
exhaustive.
This presentation is a copyright of GHL Consultants Ltd andall rights are reserved.
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G H L C O N S U L T A N T S
L T D
GHL’s Role
To know and understand the Code.
To know and understand the fire science behind the Code.
To assist in correct application of the Code.
To develop new solutions based on fire science to enable creative safe buildings.
To understand the needs of the client and of the Authorities and First Responders.
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G H L C O N S U L T A N T S
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GHL Team
7 Engineers, 4 with Master’s degrees in fire science
1 Architect
4 Certified Professionals (CPs)
2 former Building Officials
4 Building Code Qualified (BCQ)
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G H L C O N S U L T A N T S
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Building Code Committee Work
CP Committee (David Graham)
APEGBC Building Code Committee (John Buscemi)
BC Building Code Appeal Board (Frankie Victor)
City
of
Vancouver
Building
Bylaw
Appeal
Board
(Teddy Lai)
BC Building Code Interpretation Committee (Teddy Lai)
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G H L C O N S U L T A
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Building Code Approach To Risk
Buildings are subject to risks:
Code compliance ≠no risk.
Code compliance = risks at acceptable level.
Failure will occur:
Limit it to an acceptable level.
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G H L C O N S U L T A
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Building Code’s Building
The Building Code’s ‘building’ has:
Maximum travel distance
Exits at full capacity
Minimum
ceiling
height
(2100mm) Minimum access to exit width (1100mm corridors)
6m dead‐ends in public corridors
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G H L C O N S U L T A
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Building Code’s Building
Base = unsprinklered floor area, 30m travel distance
High‐hazard industrial ‐ 5m = 25m Sprinkler* + 15m = 45m
Service space + 20m = 50m
Open
air
storage
garage
+
30m =
60m Perimeter exits 60m apart unlimited travel distance
Public corridor** travel distance x 2
“Mall” corridor + 75m = 105m (50% of occupants)
* Does not apply to high-hazard industrial occupancies
** Does not apply to “mall” corridors 8
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G H L C O N S U L T A
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Building Code’s Building
Example ‐ 45m travel distance, 2 exits, 2.1m ceiling height.
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G H L C O N S U L T A
N T S
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Elements of Evacuation
Geometry – dimensional and spatial features of the space.
Demographics – characteristics of occupants; mobility. Psychology – potential occupant behaviour in fires.
Tenability – visibility, breathability, toxicity, heat.
The following presentation focuses primarily on Geometry,
which can be expressed in terms of time.
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G H L C O N S U L T A
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Travel distance translates to time to walk across the room.
All
else
being
equal,
increasing
travel
distance
simply
increases time to evacuate.
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Geometry – Travel Distance
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G H L C O N S U L T A
N T S
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Geometry – Travel Distance
Pathfinder is an agent-based emergency egress simulator developed
by Thunderhead Engineering Inc. It utilizes the floor layout, occupantload and predictable elements of occupant behaviour as input to
simulate the movement time. The simulator has been well validated
through comparison to hand calculations, real life experiments and
other software.
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G H L C O N S U L T A
N T S
L T D
Exit capacity (width) translates to time to pass through a
corridor, door or down a stair.
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Geometry – Exit Capacity
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G H L C O N S U L T A
N T S
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914mm
1828mm
Geometry – Exit Capacity
914mm
1828mm
Same floor area. Same occupant load.
Increased exit capacity = reduced time.
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G H L C O N S U L T A
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2 x 1828mm = 3656mm4 x 914mm = 3656mm
Geometry – Exit CapacityIncreasing number of exits without increased aggregate
width has no impact.
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Occupant load determines queuing time.
Higher occupant load / longer queue / increased time.
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Geometry – Exit Capacity
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1.2m
2
/person
1.2m2/person120 persons
180 persons
Geometry – Exit CapacitySame exit capacity. Same number of exits.
Higher occupant load = increased time to egress.
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60 persons
10m x 10m
60 persons
15m x 15m
Geometry – Exit Capacity
Same exit capacity. Same occupant load.
Smaller floor area = shorter travel distance.
Equal time to egress.
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The Building Code’s factors for exit capacity are a simplified
method of determining time to pass through a corridor,
door or down a stair.
Geometry – Configuration of Exits
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Effective width
= 4 x (914mm-300mm)
= 3536mm
2 x 1828mm = 3656mm4 x 914mm = 3656mm
Effective width
= 2 x (1828mm-300mm)
= 3596mm
Geometry – Configuration of ExitsReduced total effective width = increased time to egress.
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Geometry – Configuration of Exits,Pinch Points and Obstructions
Elements that hinder egress by creating pinch points or reducing capacity of access to exit:
Vestibules at exits (interconnected floor space).
Use of entry for ticket collecting, security, displays.
Retail anti‐theft equipment.
Turnstiles.
Etc.21
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Geometry – Ceiling HeightRelationship between ceiling height, or volume of space, and time to egress is codified in Sentence 3.4.2.5.(1):
Corridor 1100mm x 2100mm / Travel distance 45m
Corridor 9000mm x 4000mm / Travel distance 105m
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Ceiling height translates to time before smoke descends
to
head
level.
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Geometry – Ceiling Height
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Geometry – Ceiling Height
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Occupants with locomotive disability are considered in the
average occupant travel speed.
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Demographics
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Psychology
Human behaviour is predictable….and
unpredictable.
True “panic” is mostly a myth per studies and expert opinion.• R.F. Fahy, G. Proulx. ‘Panic’
and
human
behaviour
in
fire. (2009)
Not necessary to
consider in most timed egress analyses.
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Psychology – Human Behaviour
Human behaviour can be predicted to a degree:
Behaviour upon alert to a hazard depends on occupancy:
Nightclub – unfamiliar, dark, crowded, impaired, noisy.
Home/work – familiar, sense of ownership, protective of others.
School – familiar, additional preparedness, leadership.
Weather, gender, commitment to a task, alone or in a group, focal point/leader.
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Psychology – Human Behaviour
Psychology is independent of timed egress analysis.
Not necessary to try and predict behaviour prior to
movement provided comparison is of the same:
People
Space
Conditions
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Psychology - Panic What is panic? An overwhelming fear, with or without
cause, that produces an irrational response and may spread through a group.
When do people panic? When they can see no way out of a situation.
When does it matter? When it causes action without
assessment
of
safety
What do people mean when they say panic?
What do building officials mean when they say panic?
Real panic in an emergency is rare; experts considered it a myth since
about 1970…but the movies and news channels like it.
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Psychology – Timed Egress AnalysisTimed egress analysis is a comparison of the measurable
elements of evacuation. (SFPE Handbook 4th Ed.)
Available Safe Egress Time (ASET)
Required Safe Egress Time (RSET) Margin of Safety
Evacuation Time
Pre‐movement Movement
Response
Recognition
Alarm
Detection
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Psychology – Timed Egress Analysis
Available Safe Egress Time (ASET)
Required Safe Egress Time (RSET) Margin of Safety
Movement Time
Detection / Alarm
Alert stage can be adjusted by detection
(smoke
detector
activates
sooner
than
sprinkler)
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Tenability
Upper Layer Height
Visibility
Heat flux / Temperature
Toxicity
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Tenability
Two types of computer models are used
to
gauge
tenability: Zone Model: Upper layer height
Simpler spaces
CFD Model: Tenability parameters 3D complex spaces
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Tenability
Where a straight comparison to
Building
Code
scenarios
doesn’t
tell
the whole story:
Don’t meet cumulative exit
capacity in an interconnected floor
space.
Using open stair for egress.
Converging egress routes.
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H L C O N S U L T A N T S
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Elements of Evacuation
Geometry – dimensional and spatial features of the space.
Demographics – characteristics of occupants; mobility.
Psychology – potential occupant behaviour in fires.
Tenability – visibility, breathability, toxicity, heat.
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Hand Calculation
Time to egress is the time for either:
First occupant to reach door (t1) + time to queue at door (t2)
OR
Last occupant to reach door (t3)
Time to commence movement is not considered;
assumed
to
be
the
same
for
Building
Code
and
actual
scenarios.
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Hand Calculation
Example: Comparing Building Code and alternative solution
Building
Code
Scenario Alternative
Solution
Travel Distance 45m 60m
Exits 2 x 914mm door 2 x 914mm door
Occupant Load 2 x 914 ÷ 6.1 = 300 2 x 914 ÷ 6.1 = 300
Assumption Nearest person
5m from exit
Furthest persons
45m from exit
Nearest person
5m from exit
Furthest person
60m from exit
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Hand CalculationQueuing (t2) is the limiting factor, hence 15m extra travel distance does not contribute to added evacuation time.
*assumed 5m for nearest occupant to an exit. This may vary depending on floor layout.
Building Code Scenario Alternative Solution
t 1* 5 1.1 4.5 5 1.1 4.5
t 2300
2 0.914 0.3 1.32 185
300
2 0.914 0.3 1.32 185
t 3
45 1.1 41 60 1.1 55
t 1 t 2 185 4.5 189.5 t 1 t 2 185 4.5 189.5
t 189.5s 189.5s
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Project Examples
39
1. Egress via Open Stair.
2. Cumulative
Exiting
(interconnected
floor
space).3. Egress from Two Storey Dwelling Unit.
4. Converging Egress (Department store travel distance).
5. Parkade 70m Travel Distance.
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Example 1 – Egress via Open Stair Single exit and open egress stair.
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Sentence 3.4.2.1.(1) ‐ at least two exits required
Building
divided
into
two
storey
suites
each
served
by one exit from upper storey.
Travel distance and exit capacity met by exit stair.
Open stair provided second egress route.
Timed egress, smoke model to confirm tenability.
Additional features included smoke detection for
early alert.
Example 1 – Egress via Open Stair
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Example 2 – Cumulative Exiting
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Sentence 3.4.3.2.(6) ‐ Exit stairs serving
interconnected floor space based on cumulative
occupant load.
Cumulative exiting not met.
Used convenience stair leading to exit on 1st storey
as a means of egress.
Timed egress, smoke model to confirm tenability.
Additional features included smoke detection and
smoke
exhaust
to
keep
open
stair
tenable.
Example 2 – Cumulative Exiting
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Example 3 – Egress from Two Storey
Dwelling Unit
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Sentence 3.3.4.4.(2) ‐ describes egress doors in multi‐level dwelling units at both the upper and lower
storeys. Egress door was not provided at the upper storey
Timed egress confirmed increased egress of 3 seconds.
Concern was tenability at route from upper storey.
Smoke model confirmed tenable conditions.
Draft stop was necessary.
Additional features included smoke alarms for early
alert, emergency lighting linked to smoke alarm. Fire alarm annunciation – both storeys at lower.
Example 3 – Egress from Two Storey
Dwelling Unit
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Example 4 – Converging Egress
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Mall Corridor
Back-of-house Corridor
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Example 4 – Converging Egress
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Clause 3.4.2.5.(1)(d) ‐ 50% of occupants exit via mall
corridor with travel distance of 105m.
Rear corridor converged with mall corridor.
Used mall corridor as a means of egress for 100% of
occupants.
Timed egress, smoke model to confirm tenability.
Additional features include passive smoke venting to maintain tenability.
Code compliant solution = tunnel out of the building. Are people willing?
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G H L C O N S U L T
A N T S
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Example 5 – Parkade 70m Travel Distance
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G H L C O N S U L T
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Example 5 – Parkade 70m Travel Distance
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Scenario
Number
of
Occupants
per Exit
(persons)
Maximum
Travel
Distance
(m)
Time
to
Evacuate
(sec)
1. Code Minimum using
full door capacity 149 45 219
2. Proposed Scenario 54 70 110
Sentence 3.4.2.5.(1) ‐ prescribes 45m travel distance.
Increased travel distance from centre areas.
Increased
total
exit
width
(extra
doors). Low occupant load eliminated queuing at exits.
Timed egress.
Additional features include exit signage, increased light
levels.
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G H L C O N S U L T
A N T S
L T D
Comparison of BC to IBC and NFPA 101
(sprinklered)
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Occupancy BC IBC NFPA
101
Assembly 45m 76m 76m
Care 45m 76m 61m
Business / service 45m 90m 91m
Residential 45m 76m 61m
Retail 45m 76m 76m
Industrial F1/F2/F3 25/45/45m 23/76/120m 30/122/unlimited
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G H L C O N S U L T
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Summary
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Building Code limits ‐ travel distance, ceiling height,
exit capacity ‐ define a space, create a scenario.
Real‐life scenarios are compared to Building Code
scenario.
Human behaviour is predictable / unpredictable.
Can reduce detection / alert stage by smoke detection
(operate earlier than sprinklers).
Can ‘buy time’ by increasing ceiling height or exit
capacity.
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G H L C O N S U L T
A N T S
L T D
Questions?
GHLCONSULTANTS LTD
950
– 409
Granville
Street
Vancouver,
BC
V6C 1T2
Phone
604
689
4449
Fax
604
689
4419
Email fv@ghl.ca / jhk@ghl.ca
Web www.ghl.ca
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