Magazine July-August 2023 Global.pdf

1 WFM | JULY-AUGUST 2023
Volume 6 | Issue 2
July-August 2023
FACE TO FACE
Interview with Marwa Abla,
Co-Founder & CEO, MAB Design
Studio
INDUSTRY SPEAKS
Interview with
Sreenivas Narayanan,
Technical & Compliance Director -
Middle East & Asia Pacific, Siderise
Insulation
G L O B A L
ENHANCING AESTHETICS AND
PERFORMANCE: THE SIGNIFICANCE
OF EXTERIOR CLADDING IN
BUILDINGS
Experts’ thoughts on current trends &
technologies in Exterior Cladding, Future
Opportunities, and so on..

Preface
In the world of architecture and design, there is a concept that has become a catalyst, for innovation and
aesthetic transformation; cladding. This technique, which used to be primarily functional has now become
a trend that not enhances the visual appeal of buildings but also offers numerous opportunities for the
construction industry and beyond.
In the past exterior cladding was mainly meant to protect structures from the outside elements. However, the
landscape of design has undergone a change. Cladding is now viewed as a canvas for creativity. From sleek
glass façades that reflect skylines to wooden panels that blend with natural surroundings, there are endless
possibilities. With climate change and limited resources being pressing concerns worldwide cladding has also
responded by incorporating eco materials and energy designs.
The widespread adoption of cladding brings about opportunities. Firstly, it provides an avenue for innovation
in the construction industry. Architects and engineers can collaborate to explore materials and techniques
related to cladding. This creates job prospects in a sector for professionals who are knowledgeable about
cladding installation and maintenance.
Furthermore, there are benefits associated with innovative cladding solutions. These solutions contribute to
energy efficiency by insulating buildings thereby reducing reliance, on artificial heating and cooling systems.
This in turn leads to a decrease, in carbon emissions aligning with the goals of development. As consumers
become more conscious about living in a way property with eco-friendly cladding could potentially have a
higher value in the real estate market.
Fromaperspective,claddingallowsforacombinationoftraditionandmodernity.Itenablesthereinterpretation
of architecture. Revitalizes urban landscapes by blending contemporary design with cultural heritage. In a
world that values identity and uniqueness exterior cladding provides an opportunity for individuality to stand
out amidst uniformity. However, there are still challenges to overcome. Balancing aesthetics with functionality
requires planning and execution.The durability of cladding materials especially considering changing weather
patterns raises concerns that require research and development. Ensuring safety and compliance with building
codes also demands attention.
In conclusion, the widespread adoption of cladding is not merely a trend; it is a transformative force that
reshapes skylines, industries, and attitudes toward construction. As this trend continues to evolve it presents
opportunities, for innovation, sustainability, and cultural expression.
This edition’s cover story includes the experts’ views on cladding trends & technologies, challenges, and the
future of the industry. Apart from this, read the expert’s written article covering different topics of façade &
fenestration, industry stalwarts’interviews, and case studies.
We would like to invite you to suggest topics that’re important, to you, for magazine articles. Additionally, we
highly appreciate any comments or thoughts you have regarding our published works. Write us at editorial@
wfmmedia.com.

19
32
Enhancing Aesthetics and Performance: The Significance of
Exterior Cladding in Buildings
Experts’ thoughts on current trends & technologies in Exterior
Cladding, Future Opportunities, and so on...
70
24
Enhancing Building Safety: The Synergy of Façade Design in
Fire and Wind Resistance
Ahmad Ayub, Senior Consultant - Fire & Life Safety, WSP Middle East
08
Building Safety Remediation Scheme: A Crucial Step
Towards Ensuring Safe Homes for All
Deepa Mistry FCCA, Chief Executive Officer, Building Safety Crisis
04
How Metal Buildings Withstand Extreme Weather
Conditions
Chris Egg, Business Development & Marketing Manager, Viking Steel
StructuresA
14
Why the Façade System is to be Tested for Air Infiltration
Reji Bhami, Director- Eminent International Testing Centre, Dubai, United
Arab Emirates I Hyderabad, India
61
Industry Speaks
Interview with Sreenivas Narayanan, Technical & Compliance Director
- Middle East & Asia Pacific, Siderise Insulation
DISCLAIMER: With regret we wish to say that publishers cannot be held responsible or liable for error or omission contained in this publication. The opinions and views contained
in this publication are not necessarily those of the publishers. Readers are advised to seek expert advice before acting on any information contained in this publication which are
very generic in nature. The Magazine does not accept responsibility for the accuracy of claims made by advertisers. The ownership of trademarks is acknowledged. No part of this
publication or any part of the contents thereof may be reproduced in any form or context without the permission of publishers in writing.
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Contents
Face to Face
Interview with Marwa Abla, Co-Founder & CEO, MAB Design Studio
Green Walls-Cladding by Another Name
Dr. James Glockling, Visiting Professor, University of Central
Lancashire
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How Metal Buildings Withstand Extreme
Weather Conditions
Metal Façade
Chris Egg is a blogger and marketing specialist at Viking Steel Structures. He has been writing
about metal buildings for over 5 years and has a deep understanding of the industry. Chris is
passionate about helping people find the right metal building for their needs and loves sharing
his knowledge with others. He is also a frequent contributor to the Viking Steel Structures
blog, where he writes about a variety of topics related to metal buildings, including design,
construction, financing, and maintenance.
CHRIS EGG
Business Development & Marketing Manager,
Viking Steel Structures
About the Author

You may have heard this over &
over again. Metal buildings are
resilient to extreme weather. The
reason lies in the strength of the
raw materials – steel. It is one of the
most robust materials used on earth
in construction.
Galvanised steel is coated with
zinc to prevent rusting. What’s
more, they can be designed to
tolerate extreme climate events
like hurricanes or tornados. In case
there are minor damages, it can be
repaired or rebuilt easily & faster.
So, a question that might arise in
your head is, what makes metal
buildings so strong that they
can withstand extreme weather
conditions? Let’s see them one by
one.
Metal is Ductile
It is one of the properties of metal to
stretch and bend without breaking.
This feature makes metal structures
ideal for seismic prone regions and
high wind areas. Ductility ensures
that metal can withstand a lot of
pressure and force without any
damage.
Metal is Strong
Metal is extremely strong
compared to wood or resin. What
makes it stronger is its strength to
weight ratio. For example, strength
to weight ratio for stainless steel is
~63.
Metal is Non-Combustible
Metal is not a flammable substance.
The melting point of carbon steel is
2597-2800o
F; stainless steel is 2500-
2785o
F. Simply put, a metal building
will not catch or spread fire quickly.
So, it is a safer option to protect your
assets from getting damaged.
How Resilient is A Metal
Building?
Metal Building Vs. Snow
With options like a vertical roof,
the snow will slide off easily due to
gravity. Also, metal buildings can be
designed to withstand heavy snow
loads of up to 40 pounds per square
foot.
Depending on your area, your metal
roof can be angled to slide off all the
snow on its own. You can reinforce
metal buildings’ roofs for additional
strength if you live in a heavy
snowfall area.
Metal Building Vs. Rain
Metals do not absorb water.
Moreover, if you have a vertical
roof, water will slide off quickly
without getting logged on the roof.
Additionally, you can install a gutter
that will redirect the water flow to
a drainage area keeping your metal
building dry.
Metal Building Vs. Wind
Metal structures can be designed
to withstand wind ratings of 120
to 170 miles per hour. You can get
wind certified building from your
dealer. If you live in highly windy
states like Alabama, Texas, Florida,
or others, ensure that you chat with
your metal supplier before buying
your steel building.
Usually, the metal structure has to
meet the local building codes and
guidelines before being installed on
the site. It would be best to secure
a permit before beginning the
construction work. You must attach
a blueprint of your building’s design
to this permit.
Hardboard cladding
Aluminium sliding

But What about the Building
Façades?
Façades are the exterior
appearance of the building that
gives it an aesthetic look. Of course,
façades would suffer damage in
case of extreme weather events.
But the good thing is they can be
repaired or replaced as they do not
bear main structural support. Let’s
see some examples of building
façades.
Natural stone
They are durable, unique, and add
aesthetic to your building. You can
combine them with others
Brick
You must have seen brick used
as a décor to enhance buildings’
external appearance. It adds texture
to the wall. You can get it in various
colours, blends, and textures.
Hardboard
These are horizontal panels made
of paper and lamination. They may
look like a wooden panel except for
low cost and stability.
Stucco
It is a mixture of sand, cement,
lime & water. You can apply various
coats to get the desired look.
You can add pigment in the raw
Natural Stone cladding
Stucco cladding

mix to lessen the maintenance &
repainting.
Corrugated Steel Panels
Steel panels are the best choice if
you are looking for a modern chic
industrial style home. Long lasting,
easy installation, and affordable,
what else do you need? It comes in
various colour options.
Aluminium Sliding
Moisture problem – check; rusting
problem – check; lightweight –
check! It comes in various sizes &
styles and looks great with other
façades.
Artificial Stone
Artificial or faux stone looks like
stone, except they are lightweight.
These are low density foam and
generally waterproof.
Engineered Lap Sliding
Think of it as an advanced version of
a hardboard. These are modern and
have smooth finishing. The majority
of them are moisture proof & rot
proof. You can choose the color of
your choice as well.
Metal Cladding
From a range of metals like
aluminium, copper, zinc, steel, etc.,
you can design a façade of your
choice. Aluminum façades are
moisture proof, lightweight, low
maintenance & best option for
coastal homes.
Ceramic Cladding
It is a sustainable material made of
clay. It gives fire and heat protection.
It blocks external noise.
Concrete Cladding
Concrete is durable, cheap, and can
be customised for desired shape
and texture.
3D Cladding
It is the most popular and visually
appealing. As the name suggests,
it gives a 3D appearance to the
building wall.
In A Nutshell
Metal building is the best choice
for you if you live in a place
that experiences heavy rainfall,
snowfall, hail, storm, tornado, or
hurricane. So, you can boldly go
for it. Having to rebuild the entire
structure from scratch can be a
financial pain. So, why go through
it? Get a high-quality steel building
from a reputed manufacturer & rest
assured that your possessions are
safe.
3D cladding
Corrugated Steel Panels
Concrete cladding

Building Safety Remediation
Scheme: A Crucial Step Towards Ensuring
Safe Homes for All
Building Safety
Deepa Mistry FCCA is a Senior Financial professional and Board member in the not-for-profit
sector, STEM Ambassador, mother of three, and leaseholder affected by dangerous building
cladding. As CEO of Building Safety Crisis Ltd, Deepa is heavily involved in the Polluter Pays
legislation and is the winner of the Women in Fire Safety Award for Education in 2022, Finalist of
the Brunel University Alumni of the Year 2023, Highly Commended Woman in Fire Safety 2023,
nominee for the National Federation of Building Top 100 Women in Construction and Women in
Construction Influencer. Her aim is to make the residential environment safer for all, regardless of
race, gender, and social background.
Deepa Mistry FCCA
Chief Executive Officer,
Building Safety Crisis
About the Author

“Following the tragic fire at
Grenfell where 72 innocent people
lost their lives, there has been
a Pandora’s box discovery of a
quagmire of decades of building
safety failures. That’s right, in
this day and age, in the UK, we
are living in potential death traps
because of flammable cladding,
insulation, poor fire breaks, and so
on. This list is scarily, growing by
the day.”
I wrote these words two and a half
years ago under the expectation
that I certainly wouldn’t be where I
am today.
Where I am today, is exactly no
further from unburdening myself
of the property I purchased in
2010 under a governmental shared
ownership scheme that after
Grenfellin2017wasdiscoveredtobe
enveloped in a similarly and equally
dangerous form of cladding. Failed
attempts at selling the property
highlighted how serious an issue
and how widespread this problem
was, and led to my devoting an
incredible amount of personal time
to solving the“Building Safety Crisis”.
What I hadn’t fully understood was
that even though my building
had been remediated by 2018,
there was an inherent lack of trust
running through the industry, with
the resident incorrectly shouldering
the responsibility.
What is known is that the
aluminium cladding on many
post-2000 buildings is dangerous,
they are proven to be flammable,
as is the insulation, and along
with missing firebreaks would
spread a fire quicker than was
safe to evacuate all residents or
get under control. As a result of
deregulation to speed up the
homebuilding process and attract
more homeownership in the UK,
How the Building Safety Remediation Scheme is to be funded, and wide
ranging support across British industries

decades of cost-cutting led to the
bottom line being more important
than residential safety.
The cladding needs to come off. The
firebreaks need to be built in.The fire
alarm systems should be in place.
Effective fire management systems
should have been fitted at the
time of building such as sprinklers.
They are in the offices we work in,
so why has this been neglected
in the homes we live in? I spent
months watching contractors put
up scaffolding to remove cladding,
insulation, and membrane; then
leave my building naked for 5
months in the cold winter season. I
watched the Waking Watch security
patrol my building and sit in the
top stairwell with headphones in,
unaware of any risks. I watched
with joy the scaffolding come down
until I attempted to start the sales
process.
This crisis is all about trust,
homeowners do not trust
constructors and so won’t buy again,
lenders do not trust the constructors
and so won’t mortgage a property,
and insurers do not trust the
constructors so increase premiums.
This all led to the development of a
certification called the EWS1 form
(External Wall System) in an attempt
to restore that trust. The trouble
was, however, trying to find enough
suitably qualified engineers with
the appropriate level of personal
indemnity to assess and sign off
an EWS1. This small pool was less
than 300 in number, and with a
potential 4.5m leaseholders affected,
this meant surveying blocks with
approximately 1.9-2.2m dwellings
(source Fire Safety Bill, IA HO0365,
March 2020). The possibility of being
assessed turned into an estimated
wait of 10 years, even though we
were already remediated. I couldn’t
wait 10 years to know if my building
was safe, with my daughter and sons
growing up teenagers still sharing
a bedroom. Something had to be
done.
Speaking to other residents I
realised there were hundreds of
stories similar to mine; of lives
on hold - weddings and families
delayed, job and career moves
affected, home moves halted. I
could not sit back and watch us
live this stress day in and day out,
and co-founded a community at
Building Safety Crisis Ltd where we
could share information and have
a voice. This entirely voluntarily
run organisation was the platform
Graphic explaining how protections would work under the Earl of Lytton’s Building
Safety Remediation Scheme

to launch the people’s solution
to the crisis and was informally
known as “Polluter Pays”. Through
many iterations, it was an answer
to the question of “who pays”,
“who is responsible” and “how
soon”. In 2022 it was debated by
MPs and Lords in the House of
Commons and House of Lords.
Government removed through
this work, the ruinous proposed
Leaseholder Loans. In 2023, the
formal amendment known as
the Building Safety Remediation
Scheme will be tabled as an
amendment to the Levelling Up
and Regeneration Bill. There are
groups of leaseholders excluded
in current legislation whom this
amendment will protect: those
in buildings under 11m, blocks
where the developer does not
exist, and leaseholders with more
than three properties. It also offers
full protection for waking watch,
cladding, and non-cladding costs.
The key here is to ensure all
buildings are checked, liability
correctly assigned and to stop
dangerous quality building as we
have seen so far. By using individual
building determinations, liability
is assigned outside of the courts.
This speed up the availability of
money and implementation of
remediation schemes. Cladding
manufacturers will be held
accountable for their part in the
crisis through the expanded levy.
This will restore the trust within
the industry that has been lacking
over the last few years.
We have been waiting for over
six years, and face an urgent
situation as people are living in
dangerous buildings and during
this time there have been over
25 fire safety-related full building
evacuations.
Without the protections,
blocks will continue to be un-
remediated, cause untold stress,
a mental health crisis, and delay
lives further. Please support the
Earl of Lytton’s Building Safety
Remediation Scheme and allow
residents to live safely.
Building Safety Crisis Ltd logo, depicting the emotions felt by those in flats

Why the Façade System is to be Tested
for Air Infiltration
Façade Testing
Reji Bhami has over 19 years of experience in façade testing in the Middle East, India, and other
Asian Countries. He has handled several iconic projects such as Dubai International Airport [UAE],
Hamad International Airport-Doha (Qatar), Riyad Metro Stations (KSA), Nirlon Knowledge Park-
Mumbai [India], St. Regis Hotel- Amman (Jordan), French Avenue Project (Lebanon), Cairo Festival
City (Egypt), Crescent Tower - Baku (Azerbaijan), Future Museum Dubai (UAE), etc. He has obtained
training from BSRIA (UK) as well as ATTMA for air tightness testing. Reji has completed several air
tightness tests in the Middle as part of the LEED certification programme as well as Dubai Green
Building Regulations and ESTIDAMA requirements.
Reji Bhami
Director- Eminent International Testing Centre,
Dubai, United Arab Emirates I Hyderabad, India
About the Author

Why the façade system is to be
tested for air infiltration?
If the façade system is not airtight,
several damages and issues can
occur once the resident starts to
stay in the building. Following are
the potential consequences of a
non-airtight façade assembly.
Energy loss is one of the major
problems which a resident will face
if there is excessive air leakage.
Air leaks through the façade can lead
tosignificantenergylossbyallowing
conditioned air to escape as well as
the outside air to infiltrate into the
building. This can increase heating
and cooling demands, resulting in
higher energy consumption. This is
not only increasing utility costs but
also damaging our environmental
system.
Thenon-airtightfaçadessystemmay
require more frequent maintenance
as well as repairs to address issues
such as water damage, mould
remediation, degraded building
materials, etc. This can result in
additional costs and inconvenience
for building owners and occupants.
This will also reduce the lifespan of
building components. Uncontrolled
air infiltration can accelerate the
deterioration of building materials
due to moisture exposure,
leading to premature aging and
decreased durability of the façade
components.
Excessive air leakage will create
moisture infiltration. The Non-
airtight façades can allow the
entry of moisture-laden outdoor
air into the building envelope.
This moisture infiltration can result
in condensation on all interior
surfaces, leading to mould growth,
deterioration of building
Paint peel off due to condensation
Performance Mock up test sample installed at façade testing laboratory to
check the air leakage

materials, and potential damage to
finishes, furniture, and equipment.
Prolonged moisture exposure can
compromise the structural integrity
of the building components.
This will also create severe health
issues such as respiratory issues,
allergies, and other health concerns
for occupants. Please note that
air leaks can introduce outdoor
pollutants, dust, and allergens into
the building, negatively affecting
indoor air quality.
Air leaks in the façade can allow
the transmission of external
noise into the building, reducing
acoustic comfort. This can disrupt
concentration, hinder productivity,
and create an unpleasant
environment for occupants.
How to make sure the building is
airtight?
Proper Design is required. Careful
attention should be given to the
selection of appropriate building
materials and construction
techniques to minimise air leakage
pathways. It is crucial to design and
construct façades with airtightness
in mind. Proper sealing of joints,
windows, and other openings, etc.,
along with the use of appropriate
air barriers and insulation. Once the
system is designed, this has to be
tested for air leakage testing along
with other necessary tests such as
waterpenetration,structuralstability,
building movement, etc.
High-Quality materials and
their construction are to be
properly monitored. Ensuring
the construction is carried out
meticulously and according to best
practices can significantly reduce
the likelihood of air leaks.
Proper air barrier systems take
a major role in façade design in
terms of air leakage. Installing
continuous air barrier systems,
such as membranes, sealants,
taping, etc. at critical locations can
help prevent air infiltration and
exfiltration.
Onsite chamber test method for determining air leakage
Onsite Air tightness testing method to
determine whole building air leakage test
by fan pressurising method

Regular inspections and
maintenance are also important to
identify and address any potential
air leakage issues.
ASTM E283 is one of the most
common standards being used
for determining Air leakage tests.
The standard test method was
developed by the American Society
for Testing and Materials (ASTM) to
determine the rate of air leakage
through exterior windows, curtain
walls, and doors under specified
pressure differences across the
specimen. This test is commonly
known as the“StandardTest Method
for Determining Rate of Air Leakage
Through Exterior Windows, Curtain
Walls, and Doors Under Specified
Pressure Differences Across the
Specimen.”
The purpose of ASTM E283 is
to assess the airtightness of
building components, specifically
fenestration products such as
windows, doors, and curtain walls.
The test helps determine the air
infiltration and exfiltration rates,
which are essential for evaluating
the energy efficiency and overall
performance of these building
elements.
During the ASTM E283 test, the
specimen such as façade, doors
and windows etc. is subjected to
various pressure differences across
its exterior surfaces, simulating
the conditions it may encounter
in real-world scenarios. The
pressure differences are typically
induced by a fan system, and the
airflow rate is measured with a
calibrated device under controlled
conditions.
An airtight test chamber is required
to perform an air infiltration test as
per ASTM E283. The test specimen,
which is a specific window, door, or
curtain wall assembly, is installed on
the same.
The differential pressure measuring
device will be used to measure
the range of pressure differences
between the interior and exterior
sides. These pressure differences
simulate the wind loads that the
building components would
experience during normal use.
An Air Flow Measurement system
and a calibrated fan system are used
to create the pressure differences,
and airflow is measured across
the specimen at different pressure
levels.
The rate of air leakage (in cubic feet
per minute or cubic meters per
hour) is recorded at each pressure
level, and this data is used
Onsite Air tightness testing method to determine whole building air leakage test by fan
pressurising method

to calculate the air infiltration and
exfiltration rates.
The results obtained from the
test can be compared to building
codes, standards, or project
specification requirements to assess
if the fenestration product meets the
airtightness criteria.
ASTM E283 provides a standardised
method for evaluating the
airtightness of fenestration products,
helping architects, engineers, and
manufacturers ensure that these
building components meet industry
performance standards, enhance
energy efficiency, and contribute to
a comfortable and sustainable built
environment.
ASTM E783, CWCT, BS EN 1026, BS
EN 12153, AS/NZS 4284, etc. are
similar standards for determining
air leakage through façade, doors,
and windows being used in the
industry.
Test procedures and classification
or criteria are different in each
standard. The test standards are
normally specified in the project
specifications.
The above-mentioned test
standards are specifically applicable
to façade system testing.
The building can be leaked from
other elements as well such as
leakage through the electrical
conduit, improper sealing of risers,
leakage of the HVAC system, etc.
An airtightness test can be
conducted to measure this leakage
as well.
The common airtightness test
standards are BS EN ISO 9972,
ATTMA TSL1 & TSL2, etc.
The purpose of this test is to assess
the amount of uncontrolled air
leakage through the building
envelope, including walls, windows,
doors, and other openings. The
airtightness of a building is an
important factor in determining its
energy efficiency, as air leakage that
can result in heat loss and higher
energy consumption for heating
and cooling which is mentioned
above.
During air tightness testing, the
building to be tested should be
sealed and unoccupied during
the test. All external doors and
windows should be closed, and
any openings, such as vents, should
be temporarily sealed to ensure
accurate measurements.
The test will be conducted by a
blower door system, which includes
a calibrated fan that is installed
in an exterior door or opening
of the building. The fan is used
to pressurise or depressurise the
building, and pressure sensors
are used to measure the pressure
difference between the inside and
outside of the building.
The blower door fan is set up
and installed in an exterior door
or opening. The fan is then used
to create a pressure difference
between the inside and outside of
the building.The pressure difference
is typically measured at 50 Pascals
(Pa), which is approximately the
pressure difference that occurs
under normal wind conditions.
Results and Compliance: The results
of the airtightness test can be
used to determine the building’s
compliance with airtightness
requirements specified in national
or regional building codes or
standards. In some cases, the test
results may also be used for energy
performance certifications or to
identify areas for improvement in
the building envelope.
It is important to note that specific
details of the test procedure may
vary depending on local regulations
and practices, but BS EN ISO
9972 and ATTMA TSL standards
provide a standardised method
for conducting airtightness tests
in buildings. The test is typically
carried out by trained and certified
professionals to ensure accuracy
and consistency in the results.
Mold formed on ceiling due to condensation

Green Walls-Cladding by Another Name
Cladding
Dr. James Glockling is a Principal Fire Protection Engineer within the Naval Engineering Team
of BMT, consultant, and is the current Chair of BSI FSH/16 ‘Hazards to life from fire’. He has a
degree in Chemical Engineering and a Ph.D. in nuclear engineering. Following post-doctorate
study, he worked as, a lecturer in Chemical Engineering and Fire Safety Engineering, a forensic
fire investigator, and ran research laboratories at the Loss Prevention Council (LPC), Building
Research Establishment (BRE), and the Fire Protection Association (FPA) where he ran the UK
insurance research scheme, RISCAuthority. Jim’s principal areas of expertise are in suppression
and detection technologies and complex risk mitigation scenarios. Jim is also visiting Professor at
the University of Central Lancashire and continues to work promoting resilience in the commercial
built environment and maritime sectors.
Dr. James Glockling
Visiting Professor,
University of Central Lancashire, England
About the Author

Green or living walls are becoming
a familiar feature of the built
environment. Whilst their relevance
to sustainability and net-zero might
not be clear they do present a
public statement of green intent
and do benefit city biodiversity,
air purity, thermal environment,
noise, and no doubt mental health.
With all of these benefits, whilst
possibly unpopular, there is a need
to consider the challenges that their
introduction creates for the safety
and insurability of the building they
are deployed on. Once included as
small decorative areas on buildings,
they are now proposed for much
greater expanses, covering an
entire side, or even every side, of
tall buildings, and perhaps this best
explains the current raised level of
interest in addressing their potential
fire implications. Building life safety
is normally well addressed within
our regulations, but on green walls,
there are inconsistencies between
ADB and other government guides,
and the allowance of a 2-track
system for compliance enables
them to incorporate materials and
be tested in a way that would never
pass muster in a normal façade
system for certain building types
which, in this post-Grenfell era,
seems both wrong and completely
counter-intuitive.
In my view, there is an obvious
need to stop thinking about green
walls as anything except another
form of cladding – the outmost
layer of a façade system. Building
façade engineering is an involved
and increasingly complex area that
demands very specific expertise to
ensure its whole-life performance,
meeting stringent requirements
for weather protection including
wind resistance, thermal
efficiency, acoustic performance,
light transmittance, security,
lifespan, and of course fire
safety. Engineering detailing and
installation accuracy is paramount,
and many organisations, assurance
and product certification schemes,
exist to promote quality.
A typical rain-screen type façade
system is a kit-of-parts comprising
innermost, the building’s structure
that supports it, layers of insulation,
membranes, a cavity for moisture
and air pressure management, and
outermost the building’s skin –
the visible cladding which might
normally be formed of masonry
tiles, metal composite sheets like
ACM, or a myriad of other options,
can now include green walling.
Horizontally mounted open-state
cavity barriers within the façade’s
cavity are designed to close under
the action of fire to seal against
the rear face of cladding panels
to prevent vertical spread, and
horizontal spread is restricted by
the placement of vertical closed-
state cavity barriers.
Green walling systems come in
different configurations, but a not
uncommon current design employs
plastic planting modules filled with
growing medium, the plants, and
an associated irrigation system
(plastic pipe and guttering). Now
visualise a rain-screen system where
the outermost cladding panels are
replaced by the green wall system,
and you soon realise where the
challenges lie:
• The cavity within the façade is
now bounded by the insulation
(which might be plastic) and
the plastic of the rear of the
potting system (without even
the metal sheet protection
afforded by an ACM), a
situation that has the potential
to support fire spread at a rate
greater than open-state

• cavity barriers may function,
effective cavity closure against
the often uneven profiled back
of the potting system might
be almost impossible and
closure against combustible
materials needs very careful
consideration,
• Any profiling of combustible
materials within the cavity
surface acts to increase the
available fuel load above that of
a flat surface, and
• The fire spread up the planted
vegetation.
Approved document B cites that
the external walls of buildings, in
respect of green walls, should meet
the performance criteria of full-
scale façade testing as described
in BR135 using the BS 8414 test
methodology, a demanding 8+
metre test with full room flash-
over fire simulation of 3.5 MW heat
output, used for all façade systems;
or the green wall ‘best practice fire
safety guidance document, Fire
Performance of Green Roofs and
walls, published by DCLG in 2013.
By comparison, the best practice
guide establishes fire suitability for
the whole system from the small-
scale Single Burning Item (SBI) test
of EN 13823 (1.5 metres high with
a fire heat output of just 30 kW), a
test more normally used for single
materials with flat surfaces.
Of the two options one is clearly
much more demanding than the
other and the use of SBI can be
easily criticised for its small fire
challenge and front-face-only fire
application where the problems of
fire spread within a combustible
cavity (the greatest threat) are
unlikely to be revealed at that heat
output and on that timescale. I have
observed enough BS 8414 tests to
know that the fire is severe enough
to always challenge the cavity and
its contents even if the cladding is
fully non-combustible. Those who
recall the issues in the 1980s with
combustible sandwich panels used
in the food industry, know-how
inappropriate small-scale testing
(the cone calorimeter in this case)
can promote products and give
false assurance to building systems
that behave disastrously at full-
scale (later sorted out by insurers
introducing the large scale LPS
1181 test that allowed sandwich
panels to delaminate and spill their
contents under fire at full span).
The front-face protection afforded
by the soil and plants is obviously
greatly influenced by irrigation,
plant selection, and the presence
of water and this alone introduces
some interesting considerations:
• No other product standards
allow performance to be
assessed wet for the simple
reason that at times, they
might not be wet. Is this an
abuse of BS EN 13501-1? what
if a request came along to test
other building products with a
wet flannel draped over them?
• If the safety of the building
and its occupants is linked to
the correct function of the
irrigation system, then by
default it becomes a life-safety
system in its own right and
needs to be designed, installed,
and maintained as such. For

guidance on what it takes to
make water supplies resilient, a
good starting point is the LPC
Rules for Automatic Sprinkler
Installations – it is not a trivial or
cheap matter,
• Should the green wall ever dry
out, is the building safe to use
and occupy? A question for
Building Control and the Fire
Service,
• Is a test that can be passed or
failed based upon the species
of living vegetation used a
good test?
Just as failures are caused by the
alignment of many poor factors
(the Swiss cheese model), the
same applies to the correct
operation of the systems
designed for protection – a green
wall installation justified on the
grounds of the SBI apparatus
alone must always be as wet, AND
always have the same plants, AND
those plants must always be in the
same healthy condition, AND the
presented fire must not be greater
than 30 kW, AND fire must never
enter the cavity, AND fire must
not start in the cavity (i.e. kitchen
vent), etc. With every additional
requirement, the aggregate
probability of safe function
reduces – you start to quickly
appreciate why insurers favour
non-combustible materials – they
have few other dependencies to
perform.
I must confess that it is not clear
to me why green walls have been
afforded special consideration
within Building Regulations. If
treating them as cladding systems,
excludes their use, one can only
assume that the government is
prepared to make compromises to
safety to make buildings and cities
prettier.
So how will a green wall system
of the plastic pot type fare
when subjected to the BS 8414
test? To a certain extent, this
can be answered by a recent
‘worst-case’ experiment funded
by AXA Insurance at the Fire
Protection Association’s facilities
in Moreton-in-Marsh. The material
components of an unplanted (no
soil or plants) green wall system
that, as a planted system achieved
a B-s2 d0 fire rating, were subjected
to the BS 8414 fire load with a 5m
high sample on one face of the
test rig. The tested components
included the aluminium mounting
rails, irrigation system (not water-
charged), and guttering system.
Whilst it is certain that there would
be differences in the reaction of
the front face if planted up, as
plant material dries and burns
off and growing medium dries,
the likely involvement of the
unprotected plastic in the cavity
and associated plastic pipes and
fittings remains valid. At the very
least the configuration is relevant to
an ‘under construction’scenario.
If the system installed was
compliant with the full
requirement of BS 8414 it will
not surprise the reader that the
system would fail to meet the
requirements of BR135, failing on
the grounds of both internal and
external fire spread, with the size
of fire limited only by the amount
of system installed. In under 5
minutes, the plastic had burned
out completely to the full height
of 5 metres above the crib and
proceeded to burn laterally. The
fire was extinguished soon after.
So, two systems of appraisal that
might (subject to establishing
the extent of protection afforded
by wet soil in the BS 8414 test)
give different results - this clearly
needs some thought. When testing
gaseous fire protection systems
there are a number of tests that can
be used for the determination of
the ‘extinguishing concentration’.
These vary greatly in scale from
bench-top equipment to large
rooms, but the standards state
that the value determined at the
largest scale will prevail and even
then a large safety factor is applied
to give the end-user ‘design
concentration’ - something similar
could be specified for green-walls,
but what would that mean for
systems installed on the grounds
of SBI data, if a future BS 8414 test
might give a different result? (are
we removing cladding again?)

Like any insurance company, before
providing cover for a building, AXA
needs to make a judgment on how
the prospect will perform in a fire
event. Many names and versions
are used but the key metric is
Estimated Maximum Loss, or EML.
This describes the most that are
likely to be lost to a single fire
event and consider the key routes
for mass fire spread: through the
occupied compartments of the
building, through hidden voids,
and over the external surfaces.
Grenfell and other large cladding
fires demonstrate how the poor
choice of external coverings can
communicate fires to all floors
and compartments readily – a
situation that defeats all internal
active and passive fire safety
measures. A building with a high
EML may present challenges in
terms of availability, ease, and cost
of insurance. Nick Tilley of AXA
Insurance states “Early and detailed
engagement with insurance risk
engineers and underwriters is
very important so all aspects of
project design including resilience
to wind as well as fire can be fully
reviewed. This needs to include the
robustness of monitored irrigation
systems and any backup to ensure
the plants remain healthy plus the
ongoing maintenance of both the
plants and the irrigation system”.
Other versions of green walling
do of course exist, and great
effort has been made to remove
all combustible content (aside
from the plants themselves) by
others including Vertical Meadow.
Originally a façade engineer from
ARUP, Alistair Law has developed
a hydroponic aluminium cassette
system that grows the plants in a
non-combustible medium. “The
events at Grenfell profoundly
impacted me as a façade engineer,
hence fire and biodiversity
enhancement were non-negotiable
requirements when we started
designing our living wall cladding
panel. I recognise the remaining
fire spread limitations; however, I
believe this can be addressed in
the configuration by good design
principles. Getting this right safely is
essential in restoring biodiversity to
our cities and planet, there is a lot
at stake for everyone.”The cassettes
that replace the cladding have
a flat back, are a suitable surface
for open-state cavity barriers to
seal against, and introduce no
additional combustible materials
into the all-important rain-screen
cladding void. There’s still the issue
of fire spreading up the plants to
deal with, a not inconsiderable
remaining challenge that might
demand the use of forestry-like fire
breaks, but it’s certainly a step in
the right direction for reducing the
number of combustible materials on
buildings. It is understood that non-
combustible versions (metal) of the
soil potting system format tested
are also available or proposed.

Fire, Façades, and Wind Effects: A Holistic
Assessment
Fire Safety
Ahmad Ayub is a Senior Consultant specialising in the Fire and Life Safety field since 2015. With
several years of practical experience under his belt, Ahmad is steadily developing his expertise and
understanding of fire dynamics and safety measures. Ahmad has developed a comprehensive skill
set in fire protection, prevention, and life safety systems and expertise in local and international
codes and standards including NFPA and IBC. Ahmad’s growth aligns with the evolving landscape
of fire safety practices, highlighting his dedication to continuous learning. Exploring Ahmad’s
experiences offers insights into the journey of a determined fire consultant committed to
enhancing life and property protection.
Ahmad Ayub
Senior Consultant - Fire & Life Safety,
WSP Middle East
About the Author

The concept of Fire and Life Safety
holds a pivotal role within the realm
of building and structural design,
encompassing a multitude of vital
components including Architecture,
Mechanical, Electrical, and Plumbing
(MEP)systems,aswellasthedesignof
façades. While each of these aspects
plays a crucial role in ensuring the
safety of occupants, the focus on
developing and implementing
fire-resistant façades has notably
gained momentum on a global
scale in recent times. This growing
attention is a result of an increased
understanding and consciousness
regarding the potential risks
associated with fire incidents and, in
part, due to unfortunate occurrences
of fires that specifically involved
building façades.
This heightened emphasis on fire-
safe façades is not just a localised
phenomenon but rather a global
response to a series of incidents
that have highlighted vulnerabilities
within building exteriors. It reflects a
collectivecommitmenttoproactively
address potential fire risks and
implement advanced preventative
measures. The adoption of stringent
regulations and standards regarding
façade design further underscores
Source: archinect.com
Source: securonorway.com
the serious intent behind enhancing
Fire and Life Safety in buildings.
Façade Designs and Approaches
Building codes and standards
establish specific guidelines for
constructing façades to mitigate
the impact of fires involving
these exterior building elements.
These regulations require façades
to be prinicipally made from
non-combustible materials or
combustible materials that have
undergone testing to establish
that they comply with fire safety
standards. The objective is to
evaluate the fire performance of
external, non-load-bearing wall
assemblies, particularly when
modern construction materials
and insulation are used. A notable
example is the NFPA where an
approximately 2-storey wall
assembly is constructed to evaluate
the performance of the combustible
building materials, in a prescribed
format, but with the actual build-
up of layers intended for use in a
building. A controlled fire is then
ignited within the assembly to
replicate an interior-originating fire
breaking out to the exterior and
impinging on the façade above.

Throughout the test, various
factors like flame propagation,
temperatures within cavities, around
window openings and 2nd storey
are measured to monitor fire’s
progression.
Moreover, façade designs are
formulated to prevent continuous
vertical gaps that could facilitate the
upward spread of fire through the
“chimney effect.” A well-designed
façade must neither propagate
fire nor enable the transfer of fire
or heat between different areas
(compartmentation). It should also
maintain its structural integrity for
a reasonable duration during fire
exposure to minimise the risk of
injuriescausedbyfallingmaterialsand
debris. To obstruct potential vertical
fire pathways, non-combustible
cavity barriers are strategically placed,
often at each floor level.
The “chimney effect” refers to the
swift spread of fire within an air gap
behind the cladding. As the fire
consumes the oxygen in this gap, it
rapidly moves upward in search of
more oxygen. Fires that propagate in
this concealed gap can spread faster
than fires on the external façade due
to the buoyancy of hot air in the gap,
radiation of heat back into the fire,
andthefacadematerialbeingheated
from both the cavity and external
faces. Since the fire is concealed
behind the cladding, firefighting
efforts become challenging.
In the event of a flashover inside
a room, fire can break the external
glass and escape through a window.
The resulting flames and hot gases
can then burn facade material or
break glass above the opening,
leading to fire re-entry into the room
on the floor above. This mechanism,
known as the “Leap-Frog” effect,
has the potential to repeat itself on
successive floors. This process can
lead to rapid fire spread throughout
the building.
External wind can also significantly
impact fire dynamics. When external
wind interacts with a fire, combustion
products and smoke are expelled
from openings and/or may be forced
back toward the building façade due
to the Coanda effect. The Coanda
effect is the tendency of a ﬂow to
stay attached to a nearby surface
rather than following a straight line in
its original direction. This interaction
is a common cause of external fire
spread. Façade designs also typically
incorporateafire-ratedspandrelpanel
(typically 915 mm high) to provide a
vertical separation distance between
floors to mitigate the leapfrog effect.
The origin of the 915 mm distance is
understood to be somewhat arbitrary
and many have challenged whether
this is sufficient.
Ventilated Façades
Ventilated façade designs are
favoured globally for their
particularly energy efficiency
and therefore climate protection
benefits. A ventilated façade consists
of an outer wall, a ventilated gap,
and an inner structure. This setup
encourages airflow in the cavity
between the wall and cladding,
offering protection against weather,
reducing humidity, and providing
shadingfrom sunlight. In summer,
theheatedcavityinducesanupward
airflow, preventing excessive heat
build-up in the inner wall.
Maintainingunrestrictedairflowand
drainage behind cladding is crucial
for cavity dryness and performance.
However, this design also renders
façades highly susceptible to fires
as explained above. Due to their
extensive coverage and rapid fire
spread potential, active solutions
like exterior sprinklers are both
inefficient and costly. Thus, fire
safety should primarily rely on
passive methods, void of machinery,
sensors, or activation. Consequently,
employing cavity barriers capable
of blocking the flow of flames
and hot gases becomes pivotal in
preventing fire propagation, even in
non-combustible material façades.
Source: stonesizepanels.com

One way of achieving a ventilated
façade with a sufficient level of fire
safety is with the use of intumescent
cavity barriers attached to the
inner wall, that leave a gap behind
the outer cladding skin. These
usually include a shortened mineral
fibre cavity barrier but with an
intumescent strip on their outer
edge, which expands or swells upon
heat exposure. When exposed to fire,
the intumescent strip expands and
closes off the cavity to inhibit vertical
fire spread. To enhance fire safety
in ventilated façades, intumescent
cavity barriers can be utilised. These
barriers expand when exposed
to heat, effectively sealing gaps
and halting fire spread within the
construction.
Wind Impacts on Tall Buildings
One of the key elements in
designing fire-safe Façade systems
is to study the effects of wind and
the impact it has on fire and smoke
behaviours inside and outside of a
building. Before we delve deeper
into the wind effects on fires,
let’s look at why it is an important
consideration.
Wind Profile
The wind profile’s significance
in designing tall buildings like
skyscrapers is paramount. The wind’s
impact on tall buildings is influenced
by the wind profile – how wind
speed and direction change with
height. As buildings rise, wind forces
typically grow more significant.
Ground-level obstructions cause
turbulence and slow the wind down
while higher altitudes experience
smoother, swifter winds. Skyscrapers
tackle this through aerodynamic
design for stability.
The figures at the top indicate wind
annual wind data for two cities: a)
Dubai, UAE, and b) Wellington, New
Zealand. These figures are provided
to put into context the extent wind
speeds can reach.
These velocities are typically
measured at a height of 10 m above
ground level. Above this surface
level, the wind velocity increases
until it reaches gradient winds as
indicated in the figure below.
Influences of Wind on Fires: A
Complex Phenomenon
Wind can have diverse impacts
on fires across various stages of
their development. However,
understanding its effects remains
limited compared to other
extensively studied subjects. Smoke
movement in a building is propelled
by many factors such as buoyancy of
combustion gases, gas expansion,
ventilation systems, stack effect, and
wind. In calm air, fires are primarily
driven by buoyancy and material
combustibility. Yet, wind-influenced
fires pose intricate dynamics. Wind
significantly influences fires by
augmenting oxygen supply, and
intensifying flames and it also
reduces surface fuel humidity,
further escalating flame strength.
Although wind can also diminish
fire intensity by dispersing heat and
combustion gases, and this largely
depends on the fire location, wind
direction, availability of down-wind
fuel and geometry.
Fires On External Façade
As noted above, winds can vary in
velocity and direction depending
on the height of a building and the
terrain surrounding it. And the flow
patterns they develop when acting
against a building depend on many
Source: meteroblue (Dubai)
Annual wind data for two cities: a) Dubai, UAE and b) Wellington, New Zealand
Source: meteroblue (Wellington)
Source: meteoblue (Wellington, New Zealand)
These velocities are typically measured at a height of 10 m above ground level. Above the surface,
the wind velocity increases until it reaches gradient winds. This layer of increasing wind speed is
referred to as the wind boundary layer and the roughness of the terrain impacts the boundary layer.
This is depicted in the figure below.
Reference: https://sinovoltaics.com/learning-center/basics/location-factor-for-wind-and-solar/
How wind affects fires
concerning changes in the geometry of
flamefront in building cladding

factors such as building geometry
and shape. Several studies either
through computational models
or small-scale experiments have
been conducted to understand
how wind affects fires concerning
changes in the geometry of flame
front in building cladding.
Studies on urban and large mass
fires have found that there are
various wind-fire interactions
that play an important role in
the initiation, development, and
spread of large fires. However, we
are not aware of a conclusive study
to determine the effects of wind
on exterior structural fires. Current
studies show that:
• External wind acting
perpendicular to a fire reduce
the flame height.
• The outflow of unburned
combustible gases is
increasingly hindered by
increasingly high velocities.
• External wind acting parallel or
across (at an angle) to the fire
location cause lateral tilting of
the flame which increases its
area when compared to no
wind or perpendicular wind
condition.
These effects, from one of the
studies using a computational
model, are depicted in the figure
below.
However, most of these studies have
been conducted on a rectangular-
shaped building with no effects
considered from the adjacent terrain
on wind flow patterns or did not
account for the effect of the wind flow
patterns generated by the full building
geometry. Geometries that promote
airflow along the building promote
airflow orthatresultintheentrapment
of air pockets require further studies
and investigations to fully understand
the effects of the wind effects on fires.
A building situated in a wind flow path
creates complex and varying flow
patterns which maybe very different
from a thin façade structure.
Current Façade Fire Test
Standards
The current test standard for
façade fire performance does not
include the effects of wind when
conducting fire tests. NFPA 285
requires the test apparatus and test
specimen to be protected from
exposure to wind/precipitation
and limits the airflow across the
exterior face of the test specimen
to less than 1.3 m/s. Similarly, BS
8414 required the air velocity in
any direction shall be less than 2
m/s at the start of the test.
Test standards mainly focus on
indoor testing, often disregarding
wind effects. Introducing
wind effects in these tests
creates challenges in terms of
reproducibility and repeatability of
the test standards. And there is no
concrete proof that higher wind
velocities consistently lead to an
increased flame spread.
Lateral flame spread caused by
wind is suggested to be more
profound in the case of easily
ignitable combustible façades.
Wind-driven fires could cause
more significant fire spread in
this case due to increased area
of fire. Another aspect is the
delamination or falling of burning
debris that can be carried over to
adjacent buildings or other fuel
loads by winds and could result in
more severe consequences. This
is especially critical in areas with
densely packed buildings, narrow
streets, parking areas around
the building and limited access
that can impede the movement
of firefighting equipment and
personnel.
Typical fire plume in
BS8414
Changing the direction of the fire plume due to wind
Source: Wind effect on internal and external compartment fire exposure Daniel Brandson,
Johan Anderson, RISE Report 2018:72
No wind Side wind Diagonal wind
Wind perpendicular
to fire
Source: Effect of wind speed and direction on façade fire spread in an isolated rectangular
building, Abu-Zidan et. al, Fire Safety Journal, May 2022

Smoke Movement Inside Building
and Firefighting
Wind can affect the pressure
distributions in various parts of a
building. Wind acting directly on an
open-windowed room, increases
the room’s internal air pressure
proportionate to its speed, thereby
pushing air in, whereas rooms on
the leeward side experience lower
ambient pressure, drawing airflow out.
Room fires with broken out windows in
the presence of external wind can lead
torapidandconsiderablegrowthinthe
fire’s heat production due to increased
supply of oxygen. Importantly, where
windows are open or broken, the
external pressure previously resisted
by the facade is then transferred to
the room’s interior, acting for example
on the internal door, which is likely to
have a significant impact on its (tested)
performance.High-risebuildingscause
unpredictable airflow due to increased
altitude, and shape underlining the
importance of comprehending wind’s
effect on smoke and plume spread.
Predicting fire spread in buildings is
crucial in modern research.
Wind-driven fires pose a severe
challenge for firefighters in tall
buildings, a problem not solely
confined to brush fires, as emerging
research and incidents reveal their
significance in structure fires. Winds
directly affect combustion, offering
oxygen that intensifies flames.
Fire-generated heat and pressure
can shatter windows, while open
windows or doors for smoke venting
can interact with wind and flames. In
such scenarios, external winds can
cause unexpected flow paths inside a
building.
Flow path is the location between
where the fire is and where it wants to
go. Under no external wind, openings
yield two-way airflow: air enters at
the bottom and hot gases exit at the
top. However, with external wind,
a unidirectional flow emerges, as
wind overpowers fire-generated
pressures, driving hot gases inward.
Opening access to a fire-origin room
results in substantial fire and smoke
flow into corridors, endangering
firefighters.
Firefighter training and tactical
preparation for wind-driven fires
enhances effectiveness & reduces
injuries. Wind-driven fires, perilous
even at ground level, warrant
comprehensive understanding by all
firefighters. These fires are intricate,
unpredictable, and hard to extinguish,
especially considering resource
constraints at high elevations.This also
highlights the importance of façade
designs to accommodate high wind
pressures, maintain the stability of
perimeter fire stop and spandrel areas,
and to not delaminate when burning.
Impact on Fire Life Safety
Systems
Building structures and façades
aren’t hermetically sealed; façade
airtightnessvariesbasedonmaterials,
methods, and building purposes.
Modern focus on energy efficiency
drives airtight façade design to
reduce unwanted air infiltration
and conditioned air loss to enhance
comfort, conserve energy, and
avert moisture problems. Yet, total
airtightness remains impratical, and
complex as controlled ventilation
is sometimes vital for maintaining
indoor air quality.
Wind and external climate
can affect the performance of
life safety systems inside the
building such as smoke control
or stair pressurisation due to
differences in pressure they cause
inside a building. The leakage of
external walls and components
can detrimentally impact fan
performance.
Stack Effect
During winter, building shafts like
stairways and lift shafts experience
vertical air movement due to
warm air buoyancy against colder
outdoor air; the reverse happens in
summer. Termed the stack effect, it
notably affects smoke flow in fires.
Cold outdoor conditions enhance
upward shaft airflow, especially
when buoyant smoke is involved.
Below the neutral plane, smoke
enters and rises; above, smoke
exits to building areas. Properly
pressurised stairwells counter stack
Source: cfbt-us.com

effect, nullifying the described
smoke flow. Generally, in modern
buildings, the stack effect’s influence
on most pressurised stairwells and
elevators is minor, as the air used
in these systems is untreated and
matches the shaft temperature.
Wind
The more significant factor is
the wind pressures affecting
the shafts which can reduce the
pressure differential across the
staircase. In high-rise structures,
the wind’s external pressure can
vary greatly depending on factors
such as building shape, location,
and prevailing wind direction
and strength. Wind effects can
have a significant impact on the
effectiveness of stair pressurisation
systems in buildings. Stair
pressurisation systems are designed
to maintain a pressure differential
between stairwells and the rest
of the building, preventing the
infiltration of smoke and toxic gases
during a fire. However, strong winds
can disrupt this pressure differential.
It’s worth noting that, although lift
and stair shafts are generally well
within the building, the cumulative
effect of air infiltration through the
various sources, including the facade,
open balcony doors, open windows,
exhaust shafts, entrance doors, etc,
results in internal spaces such as lift
and stair shafts being affected.
When wind blows against the
exterior of a building, it can create
positive or negative pressure zones
on different sides of the structure.
These pressure differentials can
interfere with the intended airflow
patterns of the stair pressurisation
system, causing smoke to infiltrate
the stairwells or making it difficult
for occupants to open stairwell
doors due to increased pressure.
Wind effects play a critical role
in the performance of atrium
smoke control systems, which
are designed to manage smoke
movement in large open spaces
like atriums during fires. Wind
can significantly influence the
behaviour of smoke, potentially
complicating the system’s ability
to effectively contain and exhaust
smoke. The direction and intensity
of the wind can create turbulence
within the atrium, affecting smoke
dispersion patterns and potentially
causing smoke to spread to areas
where it shouldn’t.
In Conclusion: Interplay of Fire
Safety, Façade Design, and Wind
Effects
In essence, the design of façades
once primarily considered a
matter of aesthetics, in this context
emerged as a pivotal component in
the broader scope of Fire and Life
Safety. This paradigm shift aligns
with the evolving understanding of
the integral relationship between
building design and occupant
protection, urging architects,
engineers, and designers to
collaboratively forge innovative
paths that prioritise safety without
compromising on the aesthetic
and functional aspects of modern
structures. This transition is a call
to action, fostering a collaborative
spirit among professionals from
diverse disciplines to collectively
reimagine the concept of façade
design. Architects are challenged
to seamlessly integrate fire-
safe materials and innovative
construction techniques that
fortify façades against the
capricious nature of flames and
heat. Simultaneously, engineers
are called upon to devise systems
that harmonise fire safety features
with existing building infrastructure,
orchestrating a symphony where the
resilience of the façade resonates in
perfect harmony with the efficiency
of life safety systems.
Source: cppwind.com
Source: Effect of wind speed and direction
on façade fire spread in an isolated
rectangular building, Abu-Zidan et. al,
Fire Safety Journal, May 2022)

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Cover Story
One of the most vulnerable aspects of building design is the façade. Because the majority of the populace is unaware of
the material’s performance, they frequently misunderstand the importance of façade design, particularly in limiting or
spreading fire spread. Fire safety has traditionally been overlooked in favour of beauty, energy efficiency, cost, and other
factors. However, in light of current market trends, this has progressed beyond only the aesthetic aspect and now plays
a larger role in light conveyance, acoustical execution, and efficacy.
It is about the universal understanding of the reality that any possible fire threats can only be mitigated when façade
systems, materials, and testing are given the attention they deserve. The emphasis should be on a comprehensive
approach to examining the performance of façade materials, components of façade design for fire safety, fire testing of
façade materials, compartmentalization, and much more.
The opinions and ideas of subject-matter experts are featured in this cover story. We sought to collect their thoughts on
things like façade fire safety, laws and regulations, appropriate materials, the best approach to build a fire-safe façade,
and so on.
The importance of cladding in buildings goes beyond functionality and serves as a crucial aspect of modern
architecture. It not only protects the structure, from weather conditions but also contributes to its visual appeal.
The selection of cladding material, design, and installation technique greatly impact the building’s energy
efficiency, durability, and overall aesthetic impact. With a range of options architects, designers, and builders
can now choose from various cladding options to seamlessly integrate structures with their surroundings while
meeting sustainability and durability requirements.
In this cover story, we will delve into the role of cladding as it has the potential to transform buildings into visually
stunning and environmentally responsive works of art. For this, we have interviewed a few industry experts to
bring to you all the important aspects related to cladding. Here are the excerpts:
Mathieu Meur
Director,
DP Façade PTE LTD.
Avinash Kumar
Executive Director,
Godwin Austen Johnson
Abdulmajid Karanouh
International Director,
Head of Interdisciplinary Design &
Research, Drees & Sommer
Enhancing Aesthetics and
Performance: The Significance of
Exterior Cladding in Buildings

Types of Exterior Cladding Materials and Criteria
of Selection
According to Mathieu Meur, Director, DP Façade
PTE LTD., there are hundreds of options in the palette
of materials available to designers. These range from
translucent or transparent materials, in particular
glass and its countless declinations, to solid materials
which include several metals (steel, aluminium, zinc,
copper, etc.), various essences of timber, earth-based
materials (ceramic, terracotta, bricks), cement-based
options (architectural precast, GRC/UHPC, fibre
cement boards), to a wide variety of stones, and much
more too long to list down. Ultimately, it is up to the
façade designers to leverage this enormous range of
design options instead of confining themselves to
the ubiquitous glass and aluminium which we sadly
see on so many buildings, even though so many
alternatives are available.
There is a wide range of cladding materials out there indeed that are too many to list within
the context of this interview, and the criteria for choosing a material may vary significantly
from building to building depending on its context and complex configurations of different
factors. Materials can be listed in the following main categories.
• Wood: This material can be used as a structural and weathertight load-bearing exterior wall as
well as an external facia (rainscreen) attached to a weathertight wall. It can also be used as a
solar screen be it in the form of louvers or Mashrabiya-like lattice. Wood is normally considered
a lightweight construction material, whereas certain types, like Bamboo, are heavy-duty and
highly durable indeed, especially in hot humid environments, while having excellent thermal
insulation qualities.The affordability of wood may vary depending on its source and application,
especially when considering treatment against fire, pests, solar rays, and humidity. Depending
on the wood type, its articulation, and treatment, it can vary in its application on façades to
offer casual/cozy/friendly to high-end/luxury/elegant look and feel indeed, and therefore
can be used on various building types from simple huts to luxury palaces. Wood cannot be
recycled per se (like metal) due to its organic nature, but it can be re-used in similar or different
applications, and where certain types (like Bamboo) can grow much faster than others (like
Cedars).
• Stone: A heavy material that is normally used to project more permeance and monumentality
(palaces, museums, memorials, etc.) as well as luxury and prestige (high-end residences and
offices), as the material is considered heavy-duty (highly durable), fire-resistant, and relatively
expensive compared to other streamline solid materials like render or precast concrete.
Stone can be used for load-bearing walls (structural) and/or as an exterior cladding material
(rainscreen). Stone cannot be recycled per se (like metal) due to its organic nature, but it can
be re-used in similar or different applications. Stone cannot naturally be replaced within the
lifecycle of any building as it takes a long time to form naturally, and therefore it should be
used with a lot of careful planning to be re-used again, as our ancestors did that very well in
the past.
• Clay-based: Like Bricks, Terracotta, Ceramics, etc. that undergo a relatively low-tech process
(like baking) before they can be used for loadbearing and/or rain screen applications. Clay-
based products are relatively affordable while offering a variety of looks and feel (shiny/polished
or matt/rough, of all textures and colours) for all kinds of applications (from heavy-duty tiles
to decorative portraits). They are very durable and fire-resistant and are both recyclable and
reusable in different applications.

• Render: This is one of the oldest and most established and affordable types of façade
applications, which is mainly comprised of cementitious plaster and paint that are applied
to a weathertight wall. Render can be articulated to form all kinds of patterns, textures,
and colours, and can be applied to almost any geometrically complex surface. However,
due to its manual application, render is always prone to poor workmanship, site conditions,
and surface cracking, especially if other components are present behind it like insulation,
or if applied at the interface between different building components like a slab and wall.
Therefore, it is important to apply joints where higher building movements are expected.
Furthermore, render is also available as more industrialised/standardised insulated products,
otherwise known as Exterior Insulation Finishing Systems (EIFS) that can be applied to
simple and geometrically complex surfaces while reducing (not eliminating) requirements
for site workmanship. However, all EIFS components must be compatible otherwise the
quality could be severely compromised.
• Precast Concrete: A very heavy and heavy-duty material and affordable indeed, that can take
many shapes and sizes (units can reach up to 18m long), with fair-faced (raw look) or treated/
pigmented/painted finished surface. It is used on all types of building applications but generally
tends to be avoided on high-rise buildings due to its heaviness which adds substantial dead-load
to the main structure of the building. Precast Concrete is generally used for mid-end commercial
applications like low-rise residential units and high-end fortified buildings like ministries and
embassies. Precast Concrete cannot be recycled but can be reused in different applications.
• Glass: Due to advancements in glass technology over the past few decades, there are thousands
of glass products out there that vary in colour and level of transparency and reflectivity. From low-
iron (over 90% transparency) to mirrored glass (less than 10% transparency), glass can be used for
all kinds of applications and building types. Like metal, however, while it can project slick high-tech/
sophisticated looks, too much of it can also create a sterile look and feel.Too much glass on a building
façade can also compromise the comfort and privacy of occupants, in addition to compromising
the energy performance of the building due to high heat gain/loss (whether applied in a hot or
cold environment). Glass can come in single, double, or triple glazed units to improve thermal and
acoustic performance. Glass can be flat, single or doubly-curved either by applying cold-bending
(for relaxed curvatures – relatively cheap process) or warm-bending (for tighter curvatures – very
expensive process as it requires special three-dimensional molds). Only certain types of non-coated
glass applications can be recycled, otherwise, glass can mostly be re-used in different applications.
• Metal: Like Aluminium, Steel, Bronze, etc. metals are usually considered lightweight cladding
materials (thin sheets) when compared to heavier applications like pre-cast concrete and even
some composite materials like Glass Fibre Reinforced Cement (GFRC). Apart from commercial
coated/painted applications like composite aluminium panels, metal cladding can offer unique
and stylish looks like polished or brushed stainless steel, rusty bronze, or even rippled titanium.
Metal can be moulded and shaped to create geometrically complex surfaces and can be relatively
easily perforated due to its strong homogeneous nature. However, metal can also be relatively
expensive to fabricate and supply, and difficult to maintain. While metal cladding can project
slick high-tech/sophisticated looks, too much of it can also create an industrial/sterile look and
feel, which may alienate people. While metal is one of the most recyclable building materials, it
requires a lot of energy to do so. As they are generally considered lightweight cladding materials,
both metal and glass are widely used on high-rise buildings.

• Abdulmajid Karanouh, International Director - Head of Interdisciplinary Design & Research,
Drees & Sommer
• Composites: Like Glass Fibre Reinforced Cement (GFRC), Glass Fibre Reinforced Plastic (GFRP),
and Carbon Fibre. While GFRC is the heaviest of the 3 applications, it is still considerably lighter
than precast concrete while almost equally durable but significantly more expensive, and can
be molded into various shapes and geometric surfaces, including complex doubly-curved or
perforated ones. While less fire-resistant and durable than GFRC, GFRP can be manufactured
into much larger pieces (units can reach up to 20 meters long), however, due to its high reliance
on its fibres for its structural integrity, it likes relatively smooth and large surfaces and does
not like perforations, like a boat hull or wind turbine blade. Both GFRC and GFRP are mostly
used as non-load-bearing rain-screen cladding. Carbon Fibre is similar to GFRP albeit much
stronger (3 times the strength of steel while 12 times lighter), however, both are prone to fire
(can melt at relatively low temperatures) while Carbon Fibre is significantly more expensive
than GFRP. Therefore, Carbon Fibre is only really recommended for niche and geometrically
complex structural cladding features, like special canopies, signages, or exceptionally large
cladding units. Being lightweight, relatively durable, and easy to mould and shape, composites
are suitable for buildings that are geometrically complex and/or high-rise. Contrary to claims
made by many suppliers, composites are not exactly recyclable but can be reused in different
applications.
• Membranes & Meshes: Membranes are ultra-lightweight weathertight skins, like PVC or PTFE-
coated Fibre Glass closed-weave mesh, or transparent/printed ETFE that come as flat or air-
inflated units that look like large nylon cushions. Such materials can cover very large spans
indeed, like stadia and shopping mall roofs, and are also increasingly being used as vertical
façades. They are however prone to vandalism and sharp objects, and should therefore only
be used in parts of the buildings that are out of reach of people. Open-weave meshes tend to
allow water and air through, like PVC or PTFE-coated Fibre Glass open-weave mesh, or metal
meshes that are mostly made of stainless steel or powder-coated aluminium, and mostly used
as shading screens, decorative screens, or fences.
• Vegetation: Plants can be used as an integral part of the external façade, which can serve
as decoration, a shading screen, a privacy screen, like climbers, and help in creating a cozier
micro-climate for occupants indeed. Depending on the type of vegetation used in a particular
context, requirements for maintenance like applying pesticides, trimming, watering, etc. may
vary significantly. Vegetation may also offer occupants customisation options when allowed
to choose their plants to grow. Using vegetation as a façade element is growing in popularity,
however, more education is needed to apply it correctly. For example, certain climbers may
require a lot of watering and may also contribute to growing certain types of dangerous mold
that can infect the inner parts of the façade causing serious health issues. Other types may
attract a lot of undesirable insects and birds like mosquitos and craws respectively. Another
way for using vegetation in building façades is by creating pockets or pop-out boxes within the
building form to accommodate sky gardens or winter gardens, where plants can be grown and
maintained in a more controlled environment.

The Dubai Mall, UAE
Image courtesy: DP Façade PTE LTD.

Avinash Kumar, Executive Director, Godwin Austen
Johnson, says in terms of cladding, we are mainly using
concrete, metal, stone, and glass panels. The selection
is entirely based on the overall design intent. While
weatherproofing forms the key factor for selection,
aesthetics equally plays a major role. Right from fixing
type to the performance it achieves, there are various
factors for selection. Performance criteria are very
important in terms of human comfort and the overall
well-being of the users. FLS is one of the very stringent
criteria which needs to be reviewed while selecting and
fixing any cladding material.
Impact of Environmental Factors on the Choice of
Exterior Cladding Materials
Many factors come into play when selecting façade
materials or systems. These include aesthetics, cost,
performance, and more. When it comes to environmental
considerations, it is essential to assess the durability of the
materials through experience and testing. Beyond that,
designers need to consider the thermal performance of the
material and how this impacts the heat transfer between
the inside and outside of the building. In many instances,
it comes down more to the type of finish that is applied to
the material than the base material itself, believes Mathieu.
Environmental Factors that are Critical in Terms of Driving the Selection of Cladding Systems
& Associated Materials
• Live-loads: The first factor that is normally taken into consideration is structural integrity
and safety, which becomes especially critical the larger the cladding units and the higher the
building become, due to higher live-loads (wind pressures and building movements) applied
to the cladding. This factor becomes more complex once security requirements like blast-proof
are added to the equation. The higher live loads are applied to the cladding units, the stronger
yet more flexible the selected building material needs to be.
• Shading & Thermal Insulation: Another major driver is energy performance and the ability
of the building to reduce energy exchange between the internal and external environments
of the building. This includes the ability of the façade system/materials to shade the building
during intense sunny conditions and to insulate the building during extremely hot/cold
temperatures. The latter especially requires materials that are low in thermal conductivity like
wood and rockwool. Plastic-based materials are also low in thermal conductivity; however, they
should be used with a lot of caution as they are prone to burning or emitting high amounts
of smoke if exposed directly to fire. Introducing air gaps or inert gases into façade walls is also
common practice, like Insulated Glass Units (IGUs), double walls, hollow blocks, etc. However, if
not designed and ventilated properly, façades with cavities can cause condensation and grow
mold.
• Lighting: Another major factor is the ability of the façade to optimise and balance the admission
of natural sunlight; too much sunlight causes overheating and glare, and too little creates a dim
and lifeless environment of very low energy indeed.
• Weathertightness: This is the ability of the façade to keep rainwater out of the building
while controlling (not preventing) air infiltration. This also includes incorporating a proper
ventilation mechanism while minimising thermal bridging that could cause condensation,
especially during highly humid conditions. It is important to emphasize that no façade
system can prevent water and air infiltration 100%. Good façade design entails creating a
system that can channel water, that manages to breach or collect behind the first line of

defence, out of the building again, while controlling the ability of the façade to breathe.
The latter is especially critical when it comes to condensation; some forms of condensation
can be avoided by avoiding thermal bridging (contact of cold components with humid
air), while other forms of condensation are inevitable during highly humid conditions and
high due-point temperatures, therefore, the ventilation of cavities is very critical in this
case to avoid the collection of condensed water causing water penetration, rust, mold, and
other serious issues.
• Acoustics: The façade needs to be able to reduce noise, especially if surrounded by major
sources of noise like highways and airports, or if subjected to highly windy conditions.
Acoustics can be very tricky and counterintuitive in many ways. For example, if opening
areas in a façade screen reach about 10% of the total area of the screen, it becomes almost
useless as an acoustic barrier. Similar to thermal conductivity, using materials that are low
in acoustic conductivity is a good starting point to reduce noise. Metal for example is one
of the worst materials in terms of sound insulation due to its high-density and conductive
nature, while double walls and IGUs with incorporated air cavities/chambers tend to be
most effective in reducing noise. Also, varying the external and internal wall layers in
terms of material and thickness (like combining hollow blocks with bricks with a cavity in
between, or by introducing a laminated lite in the IGU) can increase the sound insulation
quality of façades.
• Durability & Maintenance: Façade materials need to resist several environmental
elements that could cause components to deteriorate quickly like solar rays, humidity,
salination, dust and sand, and other air particles. That said, façade materials should be able
to embrace (and not defy) such environmental elements to minimise requirements nt for
cleaning and maintenance, and extend the overall service life of the façade. For example,
cladding an entire tower with glass in a hot desert environment is counterintuitive on every
level; technical performance, user comfort, and last but least cleaning and maintenance.
The latter is especially the case as glass façades easily attract dust and sand that stick to
their surface, which in return require a lot of water (a scarcity in desert regions) to clean.
Furthermore, over-exposure to solar rays accelerates the deterioration of critical curtain-
wall components like gaskets and IGU sealants. Therefore, a careful study of the building
context and maximising the use of indigenous materials that have withstood the test of
time in the building environment is a good starting point in that respect. Finally, bird
dropping is another major challenge that we face in maintaining building façades, and
while many solutions have been applied over the years like spikes, poison, falcons, light
reflectors, ultra-sound devices, etc. none has been entirely effective in keeping birds away
from building façades. Therefore, attention to geometric articulation should be given to
avoid creating unreachable corners where birds can safely nest.
• Abdulmajid Karanouh, International Director - Head of Interdisciplinary Design & Research, Drees &
Sommer

Cladding is a “cover” to the building façade and hence
this cover does protect the users inside and hence it
must achieve the right thermal performance. It’s the
right insulation and the thermal break properties that any
cladding has to achieve to keep the external temperature
away from the inner leaf of the building, says Avinash.
Importance of Thermal Insulation for Selecting
Exterior Cladding Materials to Provide Effective
Energy Efficiency
There are multiple aspects to consider when assessing
the need for thermal insulation. In particular, one must
consider the typical temperature profile throughout the
year for the project being designed. This informs the
designer on whether insulation is needed or not, and if
so, how much insulation is required. This also determines
on which face of the wall (internal or external) it is most
judicious to place the insulation to minimise the risk of
interstitial condensation within the walls or façade. There
are other considerations, such as the fire performance of
the insulation, and whether the insulated layer can be
exposed to elements externally or not, says Mathieu.
Role of Exterior Cladding in Building’s Acoustics and
Sound Insulation Properties
Mathieu believes that the building envelope has a
substantial impact on the acoustic performance of
the building, particularly in locations where high
environmental noise is expected to occur, such as city
centres or near airports. The façade designer must
first understand what environmental noise contours
will occur near the façade, then decide on acceptable
noise levels within the building (this depends on the
building typology), and finally carefully select the
cladding materials and systems to meet these noise
levels. It should be noted that any opening within the
façade will cause severe deterioration of its acoustic
properties, so these need to be avoided. Finally, one
must consider that different materials attenuate
different sound frequencies more or less, so for more
sensitive building typologies (such as performance
venues), one needs to consider this in greater detail.
According to Avinash, windows which are a must for any
building must adhere to the right STC values to enable
the acoustics performance. The absence of this would
mean that the end-user will hear the external noise inside
the space which can be annoying. Similarly, the overall
external skin must be selected properly to keep the
external ambient noise out of the building.
Ensuring Proper Water Penetration, Resistance, and
Moisture Management
In many situations, the exterior cladding covers another
sealed envelope located behind it, such as a concrete or
brick wall. Water penetration is less of a concern in such
Commerz III, Mumbai, India
Image courtesy: DP Façade PTE LTD.

situations. The most critical areas for water tightness
are always openings (windows, curtain walls, etc.) and
interfaces between different types of envelopes (for
instance the junction between a curtain wall and a
surrounding structure). The first and most important step
is to properly design and engineer these façade systems.
It is often also essential to fully test the systems, first in
a laboratory to verify the design, and then again on-
site to assess the workmanship. Extra attention must be
paid to interfaces. Seals or flashings should be carefully
detailed and verified at the site to ensure that the building
envelope is fully watertight, opines Mathieu.
When it comes to external glazing, water infiltration
details are very important to allow moisture and rainwater
out of the building. We have observed that if the
weatherproofing is not properly, it leads to water leakages
inside the building during rains. So, it’s very important
that the windows are properly weatherproofed to avoid
water ingress, believes Avinash.
Concept of a Rain-Screen System and its Benefits in
Exterior Cladding Design
Mathieu explains a rain-screen system consists of an
exterior layer of cladding with open joints, and another
layerbehinditwhichisfullysealedtopreventairandwater
infiltration. This differs from the more traditional cladding
designs, for which the external layer has sealed joints.
The rain-screen approach is superior to this traditional
sealed joint design, as the open joints allow the wind to
pass through them, and to pressurise the cavity located
between the cladding and back wall. Since the cavity is
pressurised, rainwater does not get pushed (or sucked)
through the joints by the wind. Therefore, although the
joints are open, very little water, if any, is getting past
the external cladding layer. Another advantage of this
approach is that the absence of sealant in the joints
greatly reduces maintenance requirements. Finally, since
wind pressure is equalised between the two sides of
the external cladding layer, the latter can be optimised
structurally, resulting in savings in terms of the size or
thickness of the cladding components.
A rain-screen is generally considered a lightweight
external cladding layer that keeps most of the rainwater
away from the weathertight line of the building. It does
not contribute to the structural stability of the building
as it is normally fixed to either a load-bearing wall or to
a secondary structural system that translates the rain
screen’s dead-load and live-load reactions back to the
main frame of the building. A typical example of rain-
screen cladding would be aluminium composite panels
or EIFS render systems, says Abdulmajid.
Rain screen cladding is the cladding that covers the
building from heat, window, and moisture, and the
cavity can be ventilated or non-ventilated. The cavity has
provisions where a limited water ingress can be controlled
and it drains on its own. This cladding always helps in the
aesthetics of a new building but it can be very effective
in the case of renovating old buildings as well, believes
Avinash.
CladdingMaterialsPerformanceinTermsofFireResistance
This is a very complex topic that could justify a whole book
being written on it! Different geographies have different
ways of dealing with the fire performance of façade.
Broadly speaking, when selecting façade materials, the
fire authorities of most countries require them to be non-
combustible and not promote the spread of flame over
their surface. Other aspects that are sometimes taken into
consideration may include whether the materials produce
flaming droplets or toxic smoke. However, this all only
looks at the performance of the cladding material itself.
The overall behaviour of the assembled cladding system
should also be considered. In particular, the cladding
system should not promote the spread of flame vertically
or horizontally across the building (chimney effect), and
it should also not allow the fire to spread from floor to
floor. This requires the designer to carefully consider both
the cladding materials and overall system construction, as
well as perform testing on both the materials and systems
to verify their respective behavior, suggests Mathieu.
According to Abdulmajid, a good starting point is to
understand and appreciate that there is only so much
that can be done to prevent fires from breaking out and
reachingthebuildingfaçade,simplybecausemostinterior
finishes comprise combustible materials like fabric, wood,
and plastics, that always tend to catch fire and reach the
façade easily. It is also important to highlight that most
fire-related fatalities are due to suffocation from toxic
smoke, less so much from burns. Therefore, in addition
to avoiding using combustible materials on façades, it is
equally if not more important to make sure that façades
are designed in a manner to compartmentalise each floor
to minimise smoke spreading from one level to another.
Last but not least, most internationally recognised fire
tests are designed to keep the fire from spreading from
one level to another long enough (around 45 minutes)

for firefighters to reach the building site. However, during
special events like New Year’s Eve, traffic congestion
may delay the arrival of firefighters which may have
catastrophic consequences as fire can quickly spread out
of control. Therefore, avoiding using materials that can
become fuel to fire or generate a lot of smoke is always
the safest bet.
With the above said, brittle materials like stone,
cementitious or clay-based applications tend to
perform best in terms of fire resistance as they do not
‘burn’, melt/drip, or generate smoke when directly
exposed to fire, and are therefore considered among
the best choices in that respect. Both glass and metal
cladding do not burn or generate smoke as such (if free
of plastic components) but may break/melt if exposed
directly to the fire. While fire-resistant glass products
exist out there, comprising multi-laminated layers, they
are mostly used for internal applications as opposed
to exterior cladding. Wood, PVC, and other plastic-
based combustible materials need to be used with
caution; they may be used as external shading devices
but should be kept away from the main skin of the
building, especially on high-rise buildings. PTFE-coated
fabric and ETFE membranes simply evaporate and
emit little to no smoke when exposed directly to the
fire. Overall, the façade consultant needs to distinguish
between different types of façade components and
choose the right material accordingly; main structural
components need to be more fire resistant than others,
weather-tight skins need to avoid emitting smoke, and
decorative materials need to avoid burning/dripping.
Guoco MidTown Singapore
Image courtesy: DP Façade PTE LTD

Avinash believes that it is the flame spread that defines
the overall flame propagation. In normal cladding,
the flame spread is controlled and also there are cavity
barriers that contain the fire in specified zones or floors
in an unfortunate case of a building fire. The whole idea is
that the flame spread should be as per code and secondly
the flame/fire should be always controlled in zones in
case of fire so that the whole building is not affected.
Common Challenges Related to Exterior Cladding
Maintenance and Strategies to Ensure Longevity
and Durability
According to Mathieu, the most common challenge
is that many building owners expect their façades to
be maintenance-free in the literal sense! No façade
is ever maintenance-free, but designers can certainly
minimise maintenance issues through simple design
considerations, such as selecting materials adequate for
a specific geography and weather conditions, minimise
the use of customised elements (to facilitate future
replacement), managing the flow of rainwater within the
design (slope horizontal surfaces away from the façade,
including drip grooves/edges, etc.) and minimise or
avoid the use of materials that could increase the level of
maintenance required (e.g., certain types of sealant).
Any building needs access to the façade for general
maintenance. It can be cleaning or replacing the panels
or system installed. For general BMU systems, we do have
limited options which many times does clash with the
building design, and architects try to avoid the same. We
need more robotics, suggests Avinash.
Recent Advancements in Exterior Cladding
Technologies to Improve Performance or
Sustainability
Sustainability has been at the core of our designs for a
very long time now, so it has become second nature.
There are always means of improving, though, so very
intense R&D efforts are being expanded in making our
façades even more sustainable. Some of the interesting
technologies that I have come across recently include
an LCD panel and laminated glass hybrid which has the
potential to revolutionise façades by allowing designers
to modulate the passage of light and heat through the
glass to extreme levels, and largely independently of
each other. Another interesting development to watch
out for is that of clear photovoltaic glass, allowing
building façades to generate electricity not only from
the spandrel zones but also from the much larger vision
areas. Several other research and manufacturing efforts
are geared towards reducing the carbon footprint of
the building envelope, not only from the point of view
of embodied carbon but more importantly from cradle
to cradle, says Mathieu.
Abdulmajid says maximising passive features and
the use of indigenous materials that optimise natural
ventilation and admission of diffused natural light while
minimising the need for cleaning and maintenance
respectively is always a good start to sustainable
façade design. That said, automated mechanised
solutions (external shading devices, operable vents,
electrochromic glass, etc.) linked to sensors and a
central computerised control system may also assist

Magazine July-August 2023 Global.pdf

Magazine July-August 2023 Global.pdf

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Magazine July-August 2023 Global.pdf