Fire safety provisions required in supertall buildings will be outlined in this paper. Both passive and active systems specified in the codes for normal tall buildings are briefly listed. Evacuation is a concern. The total fire safety concept of implementing software fire safety management to control hardware provisions in passive building construction and active fire protection system is recommended for existing supertall buildings in dense urban areas. A fire safety management scheme should be worked out with clear understanding on the fire dynamics in supertall buildings.

1. International Journal on Architectural Science, Volume 7, Number 2, p.57-60, 2006
57
FIRE SAFETY PROVISIONS FOR SUPERTALL BUILDINGS
W.K. Chow
Research Centre for Fire Engineering, Department of Building Services Engineering
Area of Strength: Fire Safety Engineering, The Hong Kong Polytechnic University, Hong Kong, China
(Received 22 August 2007; Accepted 9 October 2007)
ABSTRACT
Fire safety provisions required in supertall buildings will be outlined in this paper. Both passive and active
systems specified in the codes for normal tall buildings are briefly listed. Evacuation is a concern.
The total fire safety concept of implementing software fire safety management to control hardware provisions in
passive building construction and active fire protection system is recommended for existing supertall buildings
in dense urban areas. A fire safety management scheme should be worked out with clear understanding on the
fire dynamics in supertall buildings.
1. INTRODUCTION
With the rapid increase in economics and
population in the Far East and the increasing
number of non-accidental fires, fire ‘safety’ in
dense urban areas (especially the development of
big cities in China) has to be considered carefully.
Big accidental fires had happened before in
highrise buildings, cross-harbour tunnel and in
buses in Hong Kong; and in many old highrise
buildings and new shopping malls in China. Non-
accidental fires reported over the world included
arson fires in a bank, karaoke, elderly houses and
an underground railway in Hong Kong; terrorist
fires in the World Trade Centre on 11 September,
2001 (WTC-911) in USA; arson fires in
universities in Beijing; and underground railway
arson fires in South Korea and Russia. New
architectural features such as deep plan, highrise,
framed structure and well-sealed buildings; the use
of new materials; new style of living; and so many
people living in cities or ‘city groups’ would give
new fire safety problems of concern [1]. Several
big fires were reported [2-5] in tunnel, market,
shopping mall and factory in the first half of 2007
in Hong Kong.
There are many highrise buildings in the Far East.
Over half of the top 100 highrise residential
buildings in the world are found in Hong Kong.
Some of them are of height over 200 m [6]. Those
buildings of more than 40 levels (about 120 m) are
understood as supertall (or ultra highrise) buildings
in Hong Kong. Supertall buildings are those of
height over 100 m in China [7]. Now, buildings
taller than 250 m should go through performance-
based design [8]. Different heights are adopted
such as 150 m adopted (known as super high-rise)
in Ireland [9] and 350 m in Canada [10].
A very big fire happened [e.g. 11] in an old
highrise building of height only about 50 m during
the replacement of the lift on 20 November, 1996.
A fire occurred recently [12] in the 492 m Shanghai
World Financial Center, 101-level in Pudong New
Area, Shanghai, China. It took over one hour to
control the fire. Therefore, there are concerns on
fire safety in those supertall buildings. In addition,
there are possibilities [e.g. 13] to be potential
targets of terrorist attack as the WTC. Even under
accidental fires, tall buildings would give long
evacuation time [14,15] to a ‘safe place’. Further,
structural stability [16] of the tall buildings under
fire and effect to adjacent highrise buildings upon
collapse are the concerns. Both passive building
constructions PBC and active protection systems or
fire services installations FSI must be reconsidered.
Existing prescriptive codes [e.g. 17-20] are only
demonstrated to be workable only for buildings of
normal height, say up to 40 stories for ‘normal use’.
Consequences of erecting very tall buildings
(regarded as ‘tallness’ in the Council on Tall
Buildings and Urban Habitat CTBUH 1995) [16]
are not yet studied indepth and so not included in
the codes. In implementing performance-based
design (PBD) [21] through engineering
performance-based fire codes (EPBFC) which is
known as the fire engineering approach (FEA) [1]
in Hong Kong, the fire safety objectives, methods
for fire hazard assessment and risk analysis
database are not yet agreed by the professionals.
Therefore, PBD was based on the fire safety
provisions listed in the prescriptive codes [e.g. 22].

2. International Journal on Architectural Science
58
2. FIRE CODES
Most of the existing buildings fire safety codes are
for protecting against accidental fires. It was
believed that a room fire would take longer time to
flashover. There is plenty of time to evacuate
before having a well-developed fire. However,
both residential and non-residential buildings
would store quite a large amount of combustibles,
say up to 1135 MJm-2
as allowed in the code. The
fire can be big if there is sufficient air supplied,
resulted from breaking glass facades in curtain-
walled buildings.
Consequent to the WTC-911 incident [23] and so
many arson fires, there are concerns that whether
fires other than those starting from accidents should
also be considered. With so many political and
social issues, there will be a higher possibility of
having terrorist attack and arson fires than in the
past. All these would give a well-developed fire
within a short time.
Basically, fire safety requirements are listed clearly
for normal tall buildings in Hong Kong:
• Passive construction [18-20]:
- Fire Resisting Constructions
- Means of Escape
- Means of Access
• Active systems known as Fire Service
Installations [17]:
- Alarm and Detection Systems
- Fire Suppression Systems
- Smoke Management Systems
- Auxiliary Systems such as Essential
Supply System and Emergency Lightings
3. FIRE SAFETY FOR SUPERTALL
BUILDINGS
Fire safety problems for supertall buildings are:
• Long evacuation time [14].
• Direct rescue by ground applications from the
building exterior is impossible.
• Direct water application by fire fighting jets
from the building exterior is impossible.
• Normal escape routes for occupants are
downward through staircases or lifts.
• Firemen access and equipment delivery to
rescue people and fight the fire are upward
through staircases or lifts.
• Fire fighting techniques (water application,
fire ventilation, etc.) are to be applied inside
the building for ‘suppressing’ or
‘extinguishing’ the fire, ‘controlling’ is
insufficient.
Current fire safety measures in those supertall
buildings are basically following codes for normal
highrise buildings [e.g. 17-20,22] as listed above
on passive building construction and active fire
protection systems. There are no codes on fire
safety management yet. Fire Engineering
Approach (or Performance-Based Design) [1,21] is
adopted. However, the acceptance criteria are not
yet clear.
There are additional problems:
• High target potential under terrorist attack.
• Safe separation distance for adjacent
buildings in dense urban areas to avoid
domino effect if collapsed in a way different
from WTC.
Therefore, fire safety objectives on protecting
against accidental fires, arson fires or terrorist
attack fires should be clarified.
4. EVACUATION
It was reported in a TV programme that using
elevators for evacuation in one of the top five
tallest buildings over the world of height over 400
m will not have a total evacuation time (TET)
shorter than 20 minutes! Using elevators for
evacuation under accidental fires might be good
enough as it takes time to reach flashover to give a
well-developed fire. Under terrorist attack fire
such as in the WTC incident, flashover would
occur rapidly. All combustibles will be ignited to
give high heat release rate. Fire resisting
constructions designed for a standard accidental
fire with a ‘standard temperature-time’ curve might
not be able to provide protection up to the fire
resistance period (FRP), of say 4 hrs as in WTC. It
is clear that the buildings were observed to collapse
within 1.5 hrs, due to whatever reasons still under
investigation.
New architectural features, such as using so many
glass constructions, might give additional problems.
Cracking and falling down of glass panels due to
explosion or failure of the fittings for fixing the
glass panels would give a higher air intake rate to
sustain combustion. As a result, higher heat release
rates would be emitted to cause severe damages. A
big fire with long duration might be resulted due to
storing large amount of combustibles, allowed to
be up to 1135 MJm-2
[17].
The elevator shaft, if attacked by terrorists or arson,
might not be able to stand a bigger fire not
extending the FRP. Smoke (might be even flame)
spreading to the lift shaft will give additional
problems.

3. International Journal on Architectural Science
59
It appears that nothing else is more efficient than
providing more emergency exits for those ultra
highrise buildings, unless there is further scientific
research to demonstrate that fire safety
requirements for normal buildings are good enough
for those ultra highrise buildings.
Evacuation should include physical motion under
the geometrical constraints and human factors of
crowd movement under a fire. There are basically
two types of evacuation software [23]:
• Fluid particle tracking technique known as
‘one-by-one’ model.
• Travelling through staircases in highrise
buildings with empirical formula.
However, none of these models can predict
evacuation time realistically as desired for fire
engineering application at the moment. Apart from
‘verification and validation’ on different types of
buildings with consideration on ‘repeatability and
reproductability’ of the measured data, human
factors in different conditions with different races
are not yet included. The problem is far too
complicated to be solved in the coming years. For
example, ‘waiting time’ for crowd movement plays
a key role and there are always problems in
predicting it accurately. Infinitely long ‘waiting
time’ might be predicted [24] even in a simple
single level terminal under crowded conditions by
some of these evacuation softwares.
5. PRELIMINARY PROPOSAL
All the fire safety requirements can be translated to
some critical design figures such as travel distance
Dt, fire resistance period FRP [20] or number of
staircases. In fact, an equivalent index Peq for items
difficult to describe quantitatively, such as
provision of protected corridor, can be worked out.
An obvious requirement for a supertall building of
height H is to calculate the ratio x on H with
respect to normal building height Hn (say 40 levels
or 120 m in Hong Kong), and multiply the
requirement by the factor x:
nx (H / H )= (1)
For example, Dt will be shortened to Dt/x. The
number of staircases required will be multiplied by
x. The required FRP might be extended by a factor
related to x. The hazard class for designing
sprinklers might be upgraded accordingly.
6. CONCLUSIONS
Long time taken in evacuation and structural
stability even under an accidental fire for supertall
buildings should be watched. Collapse of a
supertall building to adjacent erected buildings in
dense urban areas as ‘dominos’ is a big concern.
Note that the safe separation distance between tall
buildings is not specified clearly, especially in
downtown areas developed years ago. Fire spread
over buildings, crowd movement and control, and
possibility of onsetting a mass fire under wind
action [25] should be included in hazard
assessment. In addition, there is a high target
potential of terrorist attack for symbolic buildings.
Feasibility study on using new fire protection
systems for extinguishing the fire rapidly should be
explored. Preventive measures are required such as
applying appropriate fire protective coatings to
give a longer fire resistance period. The total fire
safety concept [26] is recommended for existing
supertall buildings in dense urban areas. Software
fire safety management to control hardware
provisions in passive building construction and
active fire protection system should be worked out.
Clear understanding on the fire dynamics in
supertall buildings is necessary to draft the safety
management scheme.
ACKNOWLEDGEMENT
This project is funded by the Croucher Foundation
for the project “Active Fire Protection in Supertall
Buildings” with account number PolyU 5-2H46.
REFERENCES
1. W.K. Chow, “Fire safety in green or sustainable
buildings: Application of the fire engineering
approach in Hong Kong”, Architectural Science
Review, Vol. 46, No. 3, pp. 297-303 (2003).
2. “West Rail fire”, Apple Daily, Hong Kong, 15
February (2007).
3. “Tseung Kwan O market fire”, South China
Morning Post, Hong Kong, 31 March (2007).
4. “Sha Tin New Town Plaza fire”, Hong Kong
Economic Times, Hong Kong, 5 May (2007).
5. “Tsuen Wan electroplating workshop fire”, Ming
Pao, Hong Kong, 23 May (2007).
6. “全球摩天大廈港佔半百”, 置業家居 Property
Times, Vol. 447, pp. 67-70, 10 January (2004).

4. International Journal on Architectural Science
60
7. J. Zhu, R. Huo and W.K. Chow, “Scale modelling
studies on smoke movement in vertical shafts of
tall buildings”, Paper Presented – 2007 ASME-
JSME Thermal Engineering Summer Heat
Transfer Conference, July 8-12, 2007, Vancouver,
British Columbia, Canada (2007).
8. Y.H. You, W.K. Chow, Y.Z. Li, R. Huo, G.X.
Liao, N.K. Fong and Gigi C.H. Lui, “Survey on
geometrical aspect ratios of supertall buildings”,
Journal of Applied Fire Science, Vol. 14, No. 4,
pp. 327-338 (2005-2006).
9. D. Cahall, “Why are high-rise buildings so
contentious?”, Newsletter of Irish Georgian
Society Spring, p. 2 (2005).
10. P.A. Irwin, “Wind engineering challenges of the
new generation of supertall buildings”, Keynote
Speech – Twelfth International Conference on
Wind Engineering (12ICWE), 1-6 July 2007,
Cairns, Australia (2007).
11. South China Morning Post, Hong Kong, 21
November (1996).
12. “Workers flee after fire hits skyscraper”, Shanghai
Daily, 15 August (2007).
13. N.M. Post, “New standard for tall ‘targets’?”,
Engineering News-Record, 13 May 2002,
McGraw-Hill, New York, Vol. 248, No. 18, pp. 10,
(2002). Available in the website:
www.construction.com/NewsCenter/Headlines/
ENR/20020513a.asp
14. W.K. Chow, “Evacuation in a supertall residential
complex”, Journal of Applied Fire Science, Vol.
13, No. 4, pp. 291-300 (2004-2005).
15. W.K. Chow, “A preliminary discussion on fire
safety aspects of supertall buildings”, CPD Open
Seminar, The Institution of Fire Engineers (HK
Branch), 10 May 2007, Hong Kong (2007).
16. I.D. Bennetts, R.M. Kowalczyk, R. Sinn and M.B.
Kilmister, “Structural system for tall buildings”,
Council on Tall Buildings and Urban Habitat,
Civil Engineering Series, McGraw-Hill, New
York (1995).
17. Code of Practice for Minimum Fire Service
Installations and Equipment, Fire Services
Department, Hong Kong (1998).
18. Code of Practice for Provisions of Means of
Escape in case of Fire and Allied Requirements,
Buildings Department, Hong Kong (1996).
19. Code of Practice for Provisions of Means of
Access for Firefighting and Rescue Purposes,
Buildings Department, Hong Kong (1995).
20. Code of Practice for Fire Resisting Construction,
Buildings Department, Hong Kong (1996).
21. BS 7974 Application of Fire Safety Engineering
Principles to the Design of Buildings - Code of
Practice, British Standards Institute, UK (2001).
22. Part 0-11, BS 5588 Fire Precautions in the Design,
Construction and Use of Buildings, British
Standards Institute, UK (1990-99).
23. E.R. Galea, S. Gwynne, P.J. Lawrence, L.
Filippidis and D. Blackshields,
“buildingEXODOUS V4.0 User guide and
technical manual”, University of Greenwich, UK
(2004).
24. W.K. Chow and Candy M.Y. Ng, “Waiting time
in emergency evacuation of crowded public
transport terminals”, Safety Science, Accepted to
publish, June (2007).
25. W.M. Pitts, “Wind effects on fires”, Progress in
Energy and Combustion Science, Vol. 17, No. 2,
pp. 83-134 (1991).
26. W.K. Chow, “Proposed fire safety ranking system
EB_FSRS for existing high-rise nonresidential
buildings in Hong Kong”, ASCE Journal of
Architectural Engineering, Vol. 8, No. 4, pp. 116-
124 (2002).