43 minute read
The Real Value of U-Value
FIRE SAFETY
The British Cladding Fire Test Gets Revised
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About the Authors:
Abhishek Chhabra joined Thomas Bell-Wright International Consultants in 2013 and has been the driving force behind the expansion of the fire compliance activities into new markets. An engineer with a post-graduate diploma in finance, Abhishek brings with him valuable experience from other, larger TIC (Testing, Inspection & Certification) companies. He has been advocating the need for compliance with standards for improved safety and quality across industries for most of the last 18 years. Sujana Haridas is a post-graduate in Civil Engineering (specialised in Soil Mechanics). Before joining Thomas BellWright International Consultants, she was an integral part of the teaching faculty in a leading Institute of Technology in India, where she also led the Concrete Technology & Strength of Materials Lab. Over the course of the past 2 years, she has conducted over 400 Reaction-to-Fire tests across British, American & European standards. The wide array of products that she has tested has led her to develop a keen understanding of material behaviour in a fire scenario. She is currently handling fire propagation tests on large-scale façade mock-ups in the Fire Testing Laboratory here in Dubai.
Abhishek Chhabra
Market Development Manager,
Thomas Bell-Wright International Consultants
Sujana Haridas
Fire Testing Engineer, Thomas Bell-Wright International Consultants
The Grenfell Tragedy in 2017 which shook the United Kingdom and the world brought the spotlight on the British standard for fire performance of external cladding systems – BS 8414. This test method has been ported to standards in countries such as Australia, Malaysia, and the UAE references the same directly in their Fire and Life Safety Code. The test method is also specified directly for projects in many countries (such as the new airports coming up in India). With the increased scrutiny over façade fire safety, a revision was not unexpected.
At the same time, the 2018 revision of UAE Fire and Life Safety Code of Practice had been increasing the options for material compliance, adding several international standards to avoid alienating materials from prominent supply chains. The code also uniquely references (test) standards without their year of publication and mandates the latest revisions are to be used. The intent to ensure the use of the latest technology and understanding is a great aid to fire safety, albeit sometimes difficult for suppliers of systems that need to be re-tested to the new standard.
OVERVIEW OF THE BS 8414 TEST METHOD
The BS 8414 test method is used to evaluate the design of a system and is not a material test. It documents the fire propagation response of a specific cladding construction under laboratory conditions. The standard comes in two parts: Part 1 covers “non-loadbearing external cladding systems fixed to, and supported by, a masonry substrate”; Part 2 covers such systems “fixed to, and supported by, a structural steel frame.”
According to the Scope section of Part 1 of the new revision, this test method is for determining “the fire performance characteristics of nonloadbearing external cladding systems, rainscreen overcladding systems, and external wall insulation systems when fixed to, and supported by, a masonry substrate and exposed to an external fire under controlled conditions. The peak fire exposure is intended to be representative of an external fire source or a fully developed (post-flashover) fire in a room venting from an aperture that exposes the cladding to the effects of external flames. This part of BS 8414 is solely intended to give an indication
A close-up of the wooden crib used as the combustion chamber of the test
of fire spread across or within an external cladding system. The purpose of the test is to provide data to enable evaluation of the fire performance of the components when combined to form a complete cladding system. This part of BS 8414 does not cover the performance of the glass or its supporting frame intended for glazed window openings. This part of BS 8414 does not test the total configuration of construction incorporating additional windows, doors, balconies, or ancillary penetrations. This part of BS 8414 does not cover exposure to radiant heat from a fire in an adjacent building”.
Part 2 of the test method is for determining “the fire performance characteristics of nonloadbearing external cladding systems when fixed to, and supported by, a structural steel frame and exposed to an external fire under controlled conditions. The peak fire exposure is intended to be representative of an external fire source or a fully developed (post-flashover) fire in a room venting from an aperture that exposes the cladding to the effects of external flames. This part of BS 8414 is solely intended to give an indication of fire spread across or within an external cladding system. The purpose of the test is to provide data to enable evaluation of the fire performance of the components when combined to form a complete cladding system. This part of BS 8414 does not apply to non-loadbearing external rainscreen overcladding systems or external wall insulation systems applied to the face of a building, the fire testing of which is covered in BS 8414-1. This part of BS 8414 does not cover the performance of the glass or its supporting frame intended for glazed window openings. This part of BS 8414 does not apply to glazed curtain walling systems. This part of BS 8414 does not test the total configuration of construction incorporating additional windows, doors, balconies, or ancillary penetrations. This part of BS 8414 does not cover exposure to radiant heat from a fire in an adjacent building”.
BS 8414 does not stipulate pass/fail criteria within the standard. Report BR 135 (Fire Performance of External Thermal Insulation for Walls of Multistorey Buildings) and BS 9414 (Fire performance of external cladding systems – The application of results from BS 8414-1 and BS 8414-2 tests), first issued in September 2019, can be used to evaluate the results of the test for practical applications.
HOW IS BS 8414 REFERENCED IN THE UAE FLS CODE?
The UAE Fire and Life Safety (FLS) code use this test method in two ways:
Setting minimum compliance requirements for the use of specific materials to be used as key façade elements. This is done using a combination of small-scale material tests validating the individual reaction to fire properties of components, and the BS 8414 test method along with BR135 evaluation criteria to create evidence validating a defined design configuration. A proven design philosophy also adds to learning for designers and subcontractors of what combinations of materials and design elements can achieve the requirements.
To evaluate the specific cladding design of a particular project. As many architects and façade designers work hard to differentiate the look for a building, many different combinations of designs and materials are created. The UAE FLS Code calls for additional test evidence if the designs and materials being proposed are not part of a certified and listed system (a Certified and Listed system is one which is detailed on the website of a Certification Body who audits one or more component manufacturer’s factories as part of their Certification). In such cases, a project-specific mock-up is tested as per one of the referenced fire propagation tests (like the BS 8414).
Parenthetically, Glass Fiber Reinforced Concrete (GFRC or GRC) has an interesting difference from other types of cladding in the way it is treated in the FLS code. The code allows any of these four large scale fire propagation tests for all cladding types except GFRC/GRC: NFPA 285 or BS 8414 or FM 4880 or ISO 13785-2. For GFRC/GRC only three test methods are acceptable: BS 8414, FM 4880, or ISO 13785-2. NFPA 285 is not acceptable for GFRC/GRC.
HISTORY AND REVISION
The test method was developed to evaluate the behaviour of a cladding system when a fire breaks out of an opening (such as a window). When this occurs there is a potential for the fire
to spread via the cladding and also to re-enter the building in another compartmentalised area. The full-scale test is necessary because the smallerscale tests on individual materials don’t evaluate design elements such as joints, fixings, termination details, insulation, fire barriers, cavities, etc., and neither do they consider how the presence or reaction of one material might affect the response of an adjacent one.
As new materials and designs surface, previously unknown risks are discovered. This is why standards must constantly evolve and update. Major fire incidents are an obvious catalyst for such reviews. BS 8414 was first issued in 2002 and was initially revised in 2015. The new revision, 2020, contains significant changes, as we shall see.
HEIGHT AND A NEW LEVEL
As mentioned above, BS 8414 does not have any specific performance criteria - specifiers and jurisdictions are free to choose classification standards or their own classification criteria. BR 135 referenced in the UAE FLS code.
Originally and up to the current revision, the test apparatus (for both BS 8414-1 and BS 8414- 2) had a height of 8 meters and had two levels of thermocouples (temperature sensors) for observation and references. Now the height has been increased by 1.7 m and added a new level of thermocouples. Provision for an early termination of the test has been introduced using a reference line which is at the new level of thermocouples. In prior versions, the test could be terminated if the
A typical BS 8414-2 test rig and a test in progress
flame extended above the test apparatus. The additional height and new thermocouples in the third level provide greater insights when evaluating performance according to BR 135 or BS 9414.
IMPROVED ACCURACY
Wind speed will always influence the flame propagation in an external cladding fire. With improved accuracy of the wind monitoring equipment from ±0.5m/s (1.8 km/hr) to ±0.1m/s, the variation in test results while considering repeatability and reproducibility is expected to
A typical BS 8414-1 test in progress
reduce substantially. It may be noted that high winds are a significant element in many of the worst cladding fires, however, the difficulty of reproducing such conditions reliably in a laboratory setting means that essentially still conditions are the only option. It will also be noted that this requirement virtually excludes conducting the BS 8414 test outdoors.
MASONRY BLOCKS
BS 8414-1 applies to the situation where the cladding is supported by a masonry substrate in the
test apparatus – as opposed to a steel frame where BS 8414-2 applies. The new revision now defines the masonry substrate more precisely. Where previously the masonry blocks were specified to have minimum values for compressive strength, density and thermal conductivity, and many types of masonry blocks exceeded these requirements, now the stated values are ‘nominal’ values which are only met by a type of lightweight, thermally efficient blocks manufactured by a small number of firms in the UK. This aims to reduce any potential influence of the substrate on the results making the test more harmonized – i.e. the results should be more reliably replicated in different laboratories.
DEFINING DAMAGED AREA
The physical damage on the cladding system due to fire is an important parameter. The earlier version of standard speaks about recording post-test observations but was never keen on quantifying the damaged areas. The new standard made it mandatory to include the percent of the damaged area in the post-test observation. This provides additional data than can be used while designing the fire and life safety strategy of a given building.
USING NEW KNOWLEDGE
There are over a dozen large scale fire tests published to evaluate the fire propagation behaviour of Cladding Designs. Though the intent of all these tests is same, -- to provide criteria for cladding systems and materials that minimise the risk of a fire that spreads through the cladding (either outside or between the cladding and the building) and engulfs large parts of the building with the consequent loss of life and property for the occupants – they all approach the task differently. While many of these tests conduct a test on a flat face, the BS 8414 test apparatus has an L-shaped design in the form of a corner with a long wall and a shorter one. While most, if not all tests simulate fire exiting the building via a window opening, there are also differences in the fire itself. Gas is used in the North American test (NFPA 285) and heptane is used in the Swedish test (SP105); BS 8414 utilises a timber ‘crib’ consisting of layers of soft-wood ‘sticks’ where the wood alternates with spaces of the same size and the layers alternate in the direction of the sticks. It produces a massive amount of energy. The UAE FLS code offers a choice of the test standards as described above. Chapter (18) of the code, on Roles and Responsibilities, passes the choice of test standard to stakeholders closest to assessing the risk, rather than a one-sizefits-all approach. As the leader in the testing and certification of building elements related to Passive Fire Protection in a wide region centered on Dubai, Thomas Bell-Wright International Consultants provides both BS 8414-1 and BS 8414-2 as well as a large range of resistance-to-fire, reaction-tofire, other fire propagation, product certification, building envelope testing and façade consulting in their large Dubai facility. The company celebrated its 25th anniversary this year.
Post-test image of BS 8414-2
COVER STORY
Exterior Cladding: Design Principles and Material Choices
Cladding is one of the most important elements which ensures that the exterior of a building is protected from the elements of nature and potential sources of damage. Cladding extends the longevity and lifespan of the building. It also provides the other important benefits that include providing strength to the structure and thermal insulation to the buildings. Cladding not only protects the building envelope but also enhances the appearance of the building. It is also very important that the cladding design and the right choice of cladding material should have the right balance of aesthetics and efficiency. We interviewed the experts in the construction sector who have provided their thoughts on the cladding sector, the trends in cladding technologies & materials, the role of fire safety in external cladding systems, etc. Here are the views of experts presented in this cover story.
AbdulGhani Dallal
Operations Manager (KSA), Comelite Architecture, Structure & Interior Design
Asad Ahmed Khan
Marketing Manager - Cladding Division, NAFFCO
Tamer Nezha
Senior Project Manager/Façade Specialist, Target Engineering Construction Co LLC
Dynamically tinting electrochromic glass is a game-changer in the cladding industry THE LATEST TRENDS IN CLADDING MATERIALS
AbdulGhani Dallal, Operations Manager (KSA), Comelite Architecture,
Structure & Interior Design says, in so many ways, the façade of a building reflects the nature of architecture in a given period. It demands as much aesthetic quality as it requires functional excellence. By empowering the user with technology that can bring a paradigm shift in terms of comfort while being energy-efficient, designers are indeed looking at new ways to innovate.
Among all the solutions dotting the market, dynamically tinting electrochromic glass is a game-changer in the sector. It not only maximises natural light, but also cuts glare significantly - thereby enabling better thermal and visual comfort, and greater well-being.
He further explains, electrochromic glass (i.e. smart glass or dynamic glass) is an electronically tintable glass used for windows, skylights, façades, and curtain walls. Electrochromic glass, which can be directly controlled by building occupants, is popular for its ability to improve occupant comfort, maximise access to daylight and outdoor views, reduce energy costs and provide architects with more design freedom.
When the beauty of the stone is desired on a façade, the ultra-thin, large-format porcelain slabs in the Kalesinterflex range works best. With a flexibility radius of 5.5m, the tiles can be clad on buildings that have concave and convex surfaces. The 3mm thickness makes the slabs light in weight, making them an ideal façade material even for tall structures. Highly resistant to weather changes, wear and tear, they do not require extra care or maintenance – routine cleaning will ensure the façade always looks as good as new.
He believes that the fibre cement is an innovative material. In less than 10 years, fibre cement - consisting of cement, water, cellulose, textile fibres, and air - has emerged as an innovative material. Thanks to it, the weight of the external skin of a house has been cut by a factor of 9! That’s 90 tonnes for a house built with traditional materials (bricks, concrete, etc.), compared to 10 tonnes of fibre cement. The result is fewer raw materials, less energy, and less waste, in return for better performance and better insulation.
Asad Ahmed Khan, Marketing Manager - Cladding Division, NAFFCO believes, in recent times, the market has taken a turn towards the use of metal, stone, ceramic & fibre cement to some extent. Metal cladding or aluminium composite panels with wooden or ceramic finishes have also seen more frequent use nowadays, due to the near-identical aesthetic and given the prolonged lifetime of the façade. Ventilated façades as well, have been a subject of discussion in the region due to huge temperature differences between the internal and external environments of buildings.
According to Tamer Nezha, Senior Project Manager/Façade Specialist, Target Engineering Construction Co LLC, the latest trends in cladding materials are using the 3D printing technology. The 3D printing opens up design possibilities that were unthinkable in the past. We can take advantage of this freedom to integrate functions such as ventilation, shading and air conditioning.
THE MAJOR CHALLENGES IN THE INDUSTRIAL CLADDING SEGMENT IN THE MIDDLE EAST
Cladding dictates how a building appears and how it forms part of an overall urban environment, so the right choice of materials and appropriate design are the deciding factors in whether it is ultimately fit for purpose, say design and build professionals. Thermal, acoustic, and fire resistance requirements are vital factors and challenges to take into account, from concept design through to maintenance, and the more ambitious the project, the greater the need for attention to detail, explains Dallal.
Khan says, the Middle East market has always been a challenging arena due to its central geographical location, which means that access to various cladding materials from across the world has never been a hindrance. However, changing the mindset of developers and consultants due to the use of traditional insulation materials for buildings by default has been a challenge; albeit, there has been a paradigm shift in the understanding of the building’s thermal dynamics more recently, resulting
3D façade panels for “Museum of the Future”, UAE
3D printed façade “Deutsches Museum”, Munich
© Aurecon
in newer and more efficient material being made available in the market.
Detailing of the design façade model requires an interactive process developed by different team members, architects, engineers, and manufacturers with constantly updated and common detailed design information under design and build process, says Nezha.
SMART CLADDING TECHNOLOGIES FOR SUSTAINABLE BUILDINGS
Dallal says, cladding is getting smarter. It is also contributing to more energy efficiency. For many years, architects have been using precast concrete panels, metal screens, and timber panels as the main cladding materials, but the focus has shifted more towards sustainability, so those materials that provide cost savings to the client and help reduce the carbon footprint of a building are one of the primary considerations for designers.
Recently architects in this region have been experimenting with different materials and we have seen a few new types of cladding materials such as perforated screens, WPC panels and timber panels being used in low rise built forms and we are also starting to see an increase in the use of mineral fiber panels replacing the old traditional metal panels.
Fritted glass double glazing is also seeing a resurgence as it offers versatility and the fact that not only does it provides transparency to the building, it also helps reduce the solar gain of the built form thus reducing operational costs.
He adds, since the introduction of the new building and fire safety codes earlier this year, the only source alternative options such as rockwool or glass mineral wool to replace polystyrene-based EIFS – which has been removed from the list of approved cladding materials.
The choice of non-flammable and code-approved materials applies also to retrofit as does the need to ensure the energy efficiency of the building. The selection of materials can contribute hugely to the overall insulation of the built form to reduce infiltration which is one of the main causes of increases in HVAC loads and any measures taken to reduce the infiltration would reduce the HVAC loads which in turn reduce the overall electricity usage.
According to Khan, impending concerns over the increased power consumption of the economy has led the local authorities across the UAE to introduce certain ‘Green Building’ regulations, which encourage the use of sustainable façades which tick the boxes when it comes to how environmentally friendly, carbon-neutral or how recyclable the material is. Sustainably resourced metal cladding, solar fitted cladding, and even stone faced GRC have been emerging options for Sustainable cladding in the Middle Eastern market.
Nezha says, there is a researcher from the Technical University of Munich (TUM) who has designed the multifunctional façade elements to be digitally fabricated to allow for complete design freedom and the easy realisation of innovative concepts. The new façade, characterised by its translucency and fluid surface texture, is one of the first functionally integrated façade elements from a 3D printer, providing the interior with ventilation, insulation, and shading.
KEY FACTORS TO CONSIDER WHILE DESIGNING AND SELECTING MATERIALS FOR CLADDING
When it comes to choosing a cladding system, there is often a misunderstanding between design working life and service life. Service life can be longer or shorter than design working life, explains Dallal. He described it below:
The design working life of a cladding system is the fixed period during which it will meet prescribed design parameters, subject to specified maintenance, without abuse or repair.
The service life is the period during which it can be used economically, without abuse, with or without maintenance and repair.
The key factors to be considered while designing and selecting cladding materials are structural performance, corrosion resistance, water tightness, air permeability, thermal resistance (by conduction/ convection/ radiation), aesthetic intent and artistic finish, and reduction in carbon footprint. He adds, there are 7 factors also that influence the design working life are: Temperature, dust, wind, rain, and other weather factors are a key challenge in the Middle East region; environment; ancillary items; fasteners; workmanship; temporary conditions during construction; and maintenance.
According to Khan, aesthetics, sustainability, thermal performance, façade life, and ease of maintenance are the key factors that should be considered while designing and selecting the cladding materials.
Tamer believes that the functionality, durability, and stability of each project element depend on the selection of materials and quality of the detailing during the analysis and design.
ROLE OF CLADDING IN CONTROLLING THE INTERNAL ENVIRONMENT
Dallal notes, the primary function of the cladding is to split the indoor environment of a building from the outside in such a way that the outdoor environment will not affect the indoors. It is also best for regulating the light penetration and controlling the radiation and conduction of heat from the sun and prevents interiors from getting faded and dull. Additionally, sunshades and louvered panels allow for the reflected light to enter the building that enhances the comfort, rather than direct sunlight.
The insulation and thermal properties of the cladding decide how efficient the building’s temperature control can be. The United Arab Emirates, for instance, has a regulation as to the minimum performance parameters of an external façade, which needs to comply with the green building code when it comes to thermal transmission of a façade.
Khan elucidates that the insulation and thermal properties of the cladding decide how efficient the building’s temperature control can be. The United Arab Emirates, for instance, has a regulation as to the minimum performance parameters of an external façade, which needs to comply with the green building code when it comes to thermal transmission of a façade.
Nezha explains, the external envelope of a building is of prime importance when considering the environmental impact of a building. In particular, the external walls provide the main element of the
Rainscreen cladding’s function in summer and in winter
aesthetic impact of the building on its surroundings. They are also key elements of the envelope as a climate modifier affecting the flow of both heat and light and consequently the resulting energy required to maintain comfort conditions within the building. In the case of cladding systems, the importance of environmental issues is complemented by the fact that they can represent up to 20% of the cost of the building project.
RAINSCREEN CLADDING AND ITS ADVANTAGES
Dallal describes, a rainscreen cladding is the most efficient cladding system for construction envelope purposes nowadays. A building solution that perfectly fits into the current sustainable architecture trends; whose installation is easier than it seems. Poor façade insulation entails a significant energy loss in private homes and other buildings. On the contrary, the rainscreen cladding system favours energy saving thanks to its air cavity on the exterior façade of the building. When combining the rainscreen cladding system with an exterior insulation system, we provide the building with numerous advantages such as the increase of thermal and acoustic insulation.
Avoids condensation and humidity: This façade system reduces condensation and humidity coming both from inside and outside the building. The continuous circulation of air inside the air cavity works as an extra protection layer and removes the possible water filtrations that can slip through the cladding joints.
One of the major reasons for which rainscreen cladding is generally adopted by building designers is the aesthetic flexibility to match any sort of shape, colour or dimension required. Apart from this, thermal performance, extended lifetime, ease of installation, sustainability, etc. are just a few other added benefits that a rainscreen system can provide, says Khan.
A rainscreen cladding is the most efficient cladding system for construction envelope purposes nowadays. A building solution that perfectly fits into the current sustainable architecture trends; whose installation is easier than it seems, says Nezha. He explains the advantages of rainscreen cladding systems that include: avoiding condensation & humidity, extends the façade’s lifetime, reduces structural movements, improves thermal and acoustic insulation, increases energy efficiency, requires virtually no maintenance, and adds value to the building or home.
Advantages of Rainscreen Cladding
• Extends the façade’s lifetime: The constant ventilation inside the air cavity improves the durability of the exterior cladding material since it keeps it dry. The façade’s lifetime is even longer when using a durable and resistant material like natural slate.
Reduces structural movements: As we mentioned at the beginning, the air cavity allows maintaining a more stable temperature in the building construction envelope. This helps to prevent the risk of cracks and other structural issues. Since the structure is not subject to extreme temperature changes, it is less liable to suffer expansion or contraction movements.
Improves thermal and acoustic insulation: The insulation layer is optional, but when we combine it with the rainscreen cladding system, the thermal and acoustic insulation of the building improves significantly. This has a huge impact on health since environmental pollution is diminished and therefore are the health issues derived from the excess of noise such as stress or fatigue. Additionally, this system removes thermal bridges.
Increases energy efficiency: The rainscreen cladding makes cooling the building easier
Image 6A: Upper opening rainscreen cladding EFFECT OF FIRE SAFETY NORMS & STANDARDS IN THE CLADDING INDUSTRY
during summer and provides better control of the heating during winter, favouring both thermal comfort and energy saving. Thanks to the rainscreen cladding system, energy bills can be reduced between 30 and 40%.
Requires virtually no maintenance: Rainscreen cladding systems require almost zero maintenance, especially if you choose a cladding material that withstands adverse weather conditions like a high-quality natural slate.
Adds value to the building or home: The extra initial investment is recovered thanks to the durability, energy efficiency, and low maintenance cost of the façade. So rainscreen cladding is an excellent choice both for new construction sites and refurbishment projects.
These systems are a very advantageous solution in terms of energy and money-saving. It is a stand for a sustainable future that allows, at the same time, reducing your heating bills and increasing your home’s thermal comfort.
AbdulGhani Dallal, Operations Manager (KSA),
Comelite Architecture, Structure & Interior
Design
Image 6B: Rainscreen lower opening ventilated façade
flammability of façades over the last decade have led to the introduction of regulations that drastically revolutionised the cladding industry in the region. The norms have shifted towards façades bound by
fire-safe regulations and minimum flammability in an attempt to safeguard buildings in the case of accidental fires. Most external façades must now mandatorily classify as Class A following European Standard EN-13501-1, which classifies building materials based on flammability and likeliness to spread the fire.
The current fire safety Code in the UAE is the most updated norm & standard in the Middle East and given solution to stop the extent of lateral & vertical fire spread and stop the extent of smoke and droplets emissions, says Nezha.
VENTILATED CLADDING & ENERGY CONSERVING FAÇADES
A ventilated façade is a façade construction with an air gap between the insulation and the façade cladding. This gap is open at the top and bottom and the cladding has small open joints, thus creating a way for natural ventilation of the façade.
A ventilated façade can be viewed as a raincoat: it protects a building against the weather, while at the same time creating a healthy indoor climate. This is why it is often referred to as rainscreen cladding.
Scientific research shows that a ventilated façade has multiple benefits compared to other building techniques. When a brick or concrete wall is exposed to continuous rain, it will act as a sponge, due to the porous nature of the materials. Ventilated façades, however, allow for the water to be drained in the cavity and any other humidity to evaporate through the air gap.
The façade may get wet in the cavity because of the open joints, but this moisture will evaporate quickly thanks to the ventilation flow within the air cavity.
A ventilated façade reduces the direct solar impact on the building and reduces the thermal movement of the structure itself. With a welldesigned/constructed façade, condensation inside the façade build-up can be prevented. Algae and moisture problems do not occur in that case, because the façade is ‘self-breathing’.
Khan notes, ventilated façades are an option being explored currently and have already been implemented in a few projects in the UAE. These façades prioritise the movement of air between the façade and the external wall of a building to boost the thermal performance and energy efficiency of the building. Simultaneously, due to an obvious chance for fire spread in ventilated areas, Cavity barriers with expandable fire stop systems have also been developed to prevent the risk of fire spreads in such systems.
Nezha explains, ventilated façades are an outdoor cladding building solution that can be applied to both new build and refurbished buildings. It is of special interest to architects for several reasons such as:
Improved thermal insulation.
Improves the façades’ continuous finish
Faster to install and to clean
Ventilated façades allow for the circulation of air between the supporting wall and the cladding material, such as marble, ceramic tiling, metallic panels, etc. In this manner, the supporting wall is protected from both the cold and heat resulting in energy savings.
MATERIALS & METHODOLOGIES FOR FIRE-SAFE CLADDING
Calorific value is the amount of energy that is produced by the complete combustion of a material. This amount of energy determines how much heat a certain material contributes to a fire.
More heat simply means a faster spreading of the fire. The calorific content of a panel is indicated by its PCS (an abbreviation of the French term ‘Pouvoir Calorifique Supérieur’) value. The higher a PCS value is, the more calorific content a panel has. Noncombustible façade material has a very low calorific value and thus a very low contribution to the fire. The classification of these non-combustible materials has an upper limit on the PCS values.
In general, the lower the calorific value of a product, the better it is when it comes to fire safety. But what does this imply?
When it comes to PCS value, two panels distinct themselves, for example, fiber cement and stone wool (Rockpanel). They both have very low caloric content. Stone wool, for example, is made from natural volcanic rock basalt, which can withstand extremely high temperatures by nature.
However, to be sure of a totally fire-safe solution, it is strongly advised to use non-combustible panels and
does not risk the somewhat dodgy performance of panels that include fire retardants to ‘mask’ their high calorific value.
Certain test standards based on EN (European) & ASTM (American) standards with regards to fire performance of façades have been made compulsory by the local civil defence authorities. In general, there are 2 test methodologies when it comes to cladding materials; first being the material fire reaction test and the second being a system test which determines the product’s fire performance as part of a façade system, says Khan.
Nezha says, currently, there are too many fire-safe materials and large-scale fire testing still remain the only possible route to gain knowledge about the flammability of exterior façades. However, these assessments are very costly, destructive, and often impossible due to many practical constraints. Even when a large-scale test is performed, it is currently done on a perfectly constructed system. In reality, the systems installed onto buildings may be vastly different from the testing standards. Therefore, numerical simulations based on computational fluid dynamic (CFD) techniques are a cost-effective tool to bridge the knowledge gap and explore the
Fire compartmentation and fire barrier
Ventilated systems vented - Pressure equalised
system sensitivity to some of the parameters such as the gap widths and material thickness.
IMPORTANCE OF FIRE-SAFE DESIGN, MATERIALS, AND TECHNOLOGIES
Khan says, “As a fire & a life safety company, we have a deep understanding of the impact that fire-safe designs & materials can have when protecting lives, properties, and the environment. If anything, recent times have shown the market that fire safety should be one of the primary priorities when designing or implementing façades and building materials”.
Façade materials play a key role in fire safety, as it would be extremely difficult to control the building fire on the exterior. Hence, more focus is needed in selecting appropriate materials, and this requires designer knowledge on material behaviour and performance, opines Nezha.
THE MARKET FOR THE FIRE-RESISTANT CLADDING MATERIALS AND ITS WAY FORWARD
At this point, there is no turning back to flammable materials, even for budgetary purposes. The shift towards the use of fire-resistant has led to a chain of events for the better of the industry. NAFFCO for instance, has introduced TUF panel, aluminium composite panels and is the only company in the Middle East to manufacture the composite nonflammable core, in-house. Due to increase in fire outbreaks and huge quality control discrepancies for materials arriving from South East Asia, TUF panel introduced a methodology that would allow 100% control over the quality of the aluminium composite panels, which have been one of the major causes for fire spreads in buildings, explains Khan.
The rapidly increasing utilisation of advanced lightweight materials, including light alloys, polymers, and fiber-reinforced composites that are highly flammable poses significant fire risks impacting people, environment, and the economy, notes Nezha. They can be often found in exterior cladding systems, otherwise known as exterior insulation finishing systems (EIFS) or external thermal insulation composite systems (ETICS). These systems are designed to be cost-effective solutions for thermal insulation, weather resistance, and aesthetic external wall finishes, he adds. In the Middle East and UAE specially the most basic exterior cladding system consists of:
1. An insulation layer, often a polymer such as a polystyrene (EPS), polyisocyanurate (PIR) or polyurethane (PU);
2. A surface finish layer that can be a surface coating or a sandwich panel (such as an aluminium composite panel (ACP)).
FUTURE TRENDS FOR INDUSTRIAL CLADDING IN THE MIDDLE EAST
Dallal sees a good scope for textile façades in the Middle East. He explains fabric façades are a new trend of screens and fabric architecture used on the exterior surfaces of buildings. Both old and newly built buildings can be quickly and simply clothed. It can be used for many buildings from industrial buildings to shopping centers, stadiums to residential buildings.
Textile façade coating applications are made of textile materials using static (closed) PVC, mesh (mesh), PTFE (Teflon) laminates and/or mesh and aesthetic materials and imported textile products with guaranteed aluminium construction for the steel construction, And/or by applying special design tensioning apparatuses.
These systems, which are used in the direction of sunlight breaker function, shading and thermal insulation as well as light permeability (night and day, inside-out, far-away view) which must be perceived differently from the inside by the inside, besides their contribution to architectural appearance and aesthetics, ease of application and economic, he adds.
Khan presumes, mobile or moving façades are a trend that is currently in an experimental stage in the region and are being closely studied. Solar-based cladding is also being developed as sustainable options become more viable with an increased demand for sustainable products.
The future trends for industrial cladding in the Middle East using the software as Rhino & Revit for parametric design and digital fabrication, says Nezha.
Parametric design and digital fabrication - Rhino & Revit
Fabric façades are a new trend of screens and fabric architecture used on the exterior surfaces of buildings
Reymann Muaña Buscato
uap, Senior Architect, U+A
What are the latest trends in cladding materials?
The current trends in cladding materials based in the UAE market, and I would say even globally, are fibre cement panels, aluminium panels, and solar panel façade cladding (photovoltaic glass panels) including timber and stone cladding.
I believe that the increase in the utilisation of these materials over the years is highly driven by several core factors such as durability, design versatility, aesthetic appeal, and functionality. For example, fibre cement panels are fire and water-resistant, has good sound and heat insulation properties. In addition to that, it does not deteriorate with ultraviolet light and is eco-friendly and with the surge of sustainable building materials, creating a trend worldwide, more and more designers/ architects lean on these materials as an option.
Over the years, aluminium panels have been a trusted cladding ally of architects as it has never failed to give impressive results. It is durable, lightweight, can be thermally efficient and shaped
Damac Heights is an 84 storey residential tower with retail at ground level located at Dubai Marina with a GFA of 855,590 sq.ft. Uses a combination of aluminium composite panels and glass façade fenestration with stone cladding at the podium level
endlessly in response to the building design. Of course, the ingenuity of the architect will greatly affect the extent of usage and the manipulation of the material to fit however ambitious a design will or can be. Predictably, it would be safe to say that this type of cladding material will remain in the market for many years.
With regards to solar panel façade cladding (photovoltaic glass panels), this type is rarely being used in the UAE. Although as designers we try to incorporate this type of cladding, however, it never progresses beyond concept design. Once the design goes on further to the scheme, detail design, and especially to tender, these items are always on the list of being value engineered. Perhaps it is not cost-effective or it could be that the application of new technology regarding this is not in line with the existing market trends in the architectural arena. Hopefully, one day we can enjoy this type of building efficiency and sustainability in the future that is end-user friendly, especially on the facility management side.
Nevertheless, I am a strong believer of painted plastered concrete and glass windows. Basically, if you can combine these two elements properly into your design, then you can be able to create a costeffective, aesthetically pleasing, highly sustainable structure that can last for many years and easy to maintain. As a guiding principle, I always make sure to provide effective, safe and quality design features for clients, fully understanding that nowadays, the market is highly price-conscious and demanding in terms of product quality, longevity, or if it comes to par with the regulatory codes imposed by building authorities in the government of that particular place or country and the like, as we are catering to a diverse clientele.
What are the major challenges you find in the industrial cladding segment in the Middle East?
I can say that one of the major challenges of the industrial cladding segment in the Middle East, specifically here in the UAE is complying with the new UAE codes. Although I would consider this to be a very good initiative of the UAE government in preventing fire incidents. Rules and regulations pertaining to the suppliers, manufacturers, and installers of industrial cladding (as they are increasing in number) should be strictly implemented as negligence is very common. Cases of improper installation have caused various scenarios like rainwater leakage, detached cladding from the system, and worst is cladding falling to the ground secondary to strong winds and sandstorms.
Please brief us about smart cladding technologies for sustainable buildings.
Smart cladding is the use of materials that is quite new to the market and helps with the energy efficiency and the sustainability of the building in terms of HVAC loads, water consumption, and electrical loads. Due to the new codes being implemented in the regions, especially in the UAE, other cladding materials pop up like perforated screens, mineral fibre panels, WPC panels to name a few.
U+A creates an innovative and new residential typology for Dubai, that combines functional living with the aesthetics of a expansive landscaped podium
Midtown by Deyaar intends to create a community with a an unparalleled live and play lifestyle that incorporates high-end living with the natural surroundings of the leisure facilities. It adapts itself as an stand alone development that create a benchmark of community living with 27 total number of buildings. Midtown Community Cluster is another good example of a combination of paints, concrete and glass and good workmanship
What are the key factors to consider while designing and selecting cladding materials?
From an architect’s point of view, key factors to consider are:
Can it follow/perform the complexities of my design?
Is it locally available?
Is it economical or within the client’s budget? Because most of the projects start with a very ambitious concept and at the end, it will be value-engineered and ends up way too different from what you envisioned your design will be?
Durability
Geography where your building is located
Local and international code compliance
Constructability
Aesthetics
What role does cladding play in controlling the internal environment?
The choice of cladding will greatly affect the internal environment and it depends on the type of building that you design or build. For example, in an office building, we usually consider more natural light to come in but less heat. This is the reason why most of the office buildings use the floor to floor glass cladding or panelling. To counter glare, we use vertical and horizontal louvers, perforated panels, and photovoltaic glass panels. For the hotels and other residential buildings, there is less glass panel usage due to building code, fire codes, and privacy. It can literally dictate the mode you want to achieve for a specific building function.
Could you please tell us about rainscreen cladding and its advantages in detail?
Rainscreen cladding is a form of insulation for moisture resistance and rainwater seeping into your core walls in particular. It helps to protect your core walls against moisture. Nowadays, it has become an architectural façade cladding. Vented, vented and pressure, equalised and drained and vented are some types of rainscreen cladding to name a few. The advantages of using these types of cladding are:
Simple installation means most of the suppliers can attach to the main structural walls with ease. They can work closely with façade consultants and structural engineers.
Lightweight materials. They usually range from 4mm thick to 8mm thick sheets and weigh just less than 6 kg per square meter.
It can decrease condensation on the building if done properly. That is why it is critical for the site architects and inspectors to monitor closely when installing otherwise it will defeat its purpose. Rainscreen, usually increases airflow and can manage moisture effectively.
It can be easily removed and replaced due to its advanced fixing system. It will greatly help facility management in maintenance in the long run.
It is very easy to use. These cladding can be easily bent and rolled to fit architectural details, façade ends, and joints.
If you use rainscreen cladding, you can still achieve the aesthetic aspect of your design. For it to have a lot of colour ranges and can even request supplier, manufacturers for customised colours and join connections.
The current fire safety norms & standards and their effect on the cladding industry in the Middle East? Due to fire occurring situation here in the Middle East (UAE to be specific), the UAE fire code has been revised to address this situation. I myself have experienced a massive fire in my building way back in 2011 in JLT. Where it only starts in a very small fire at the top of the building (maybe in the electrical room) but because the building façade is cladded with ACP (aluminum composite panels, the fire just spread so quickly and the fire department could not do anything but only protect the surrounding building and the assets below. The norms now are all the new buildings that have been linked to the central monitoring facility by the fire department (civil defense authority) by incorporating BMS/ security rooms into the design. Also, all the products now for cladding have a strict testing and needs to pass the entire new requirement stated in the new fire code in the UAE. They have banned the use of all flammable insulation elements into the cladding.
Under the updated UAE fire code, consultants will be responsible for the overall operations and the lifecycle of a building, such as: acquiring the no objection certificate (NOC) from civil defense authorities; selection of approved material; contractor qualification; inspection during construction; and testing and commissioning works.
The purpose built sales centre conceptualised by U+A will become a truly striking building on Sheikh Zayed road. The centre provides its customers a platform for unparalleled interactive experiences whilst learning about new developments
Wasl Experience Center is a structure with a complex geometric form that uses a combination of aluminium composite panels and curtain wall glazing for the façades
Now, all design consultants have this approved list of building materials to follow. It was given to us by the authority to follow, materials not listed here if we insist to use must go to a rigorous process to make it pass before we can actually use it.
What are ventilated cladding energy-conserving façades?
Ventilated cladding is a method where cladding has a separation or an air gap from the main façade wall/structure. This helps prevent moisture buildup between the cladding and the main wall. This method will also help not to create a heat transfer from the exterior heat to the interior of the building does reducing energy consumption. Ventilated cladding is a form of energy-conserving façades as mentioned above.
What is the importance of fire-safe design, materials, and technologies?
This is very important. We are not only designing buildings and structure, but the safety of the endusers and the building itself to last its lifecycle. This also gives a sense of peace when you know that the building/structure that you design if safe for the end-users. We appreciate what the authorities have done because we do not need to second guess which building materials (cladding) to use for they have already provided us with the list of materials and suppliers that they have authorised or have accredited as safe here in the UAE to be specific.
What is the market for the fire-resistant cladding materials and its way forward in the Middle East?
I think it looks really bright. Most of the cladding materials now in the market are complying with the fire codes and local building codes. And from what I see, cladding in the Middle East is a must due to the weather condition. Cladding not only makes the character of the building, but also serves as protection of the main structure from weather and other exterior elements that will affect the lifecycle of the building/structure.
Commissioned by Emaar, U+A designed a residential development in the upscale Dubai Hills Estate, which includes ground floor terraced units, townhouses at podium level and a mix of one, two and three bedroom apartments
In new UAE Fire Code, they have banned the use of all flammable insulation elements into the cladding
What are the future trends for industrial cladding in the Middle East?
• Solar façade cladding panels
Graphic light façade
Perforated façade cladding
Customised aluminium cladding
NOTE:
I hope one day, our scientists and manufacturers can come up with renewable energy that can be incorporated in the façade as a design feature specially water from the tanks that flow towards our faucets can be converted back into energy for the building. That is sustainable energy. Imagine it can power your toilet lights while taking a shower or what not.
Media mesh façade cladding
