n many respects, the facade just might be the most important component of a new building. It multi-tasks in keeping out the weather and pollution while admitting natural light. It assures of comfortable temperatures and well processed air, while making a statement to the outside world. And if you’re really fortunate, it becomes an icon. In architecture, the façade of a building is often the most important from a design stand point, as it sets the tone for the rest of the building. The principle for a foundation is good design, performance and ultimately its durability. A good design and engineering is fundamental to achieve durability along with good workmanship and fabrication and supervision has a very vital role in getting the correct façade executed.
A façade needs to be designed as per the geographic location and the climate to ensure sustainability and efficiency which includes ventilation, daylight penetration and energy optimisation.In the Indian context, the most important function of the façade consists of weather tightness (against dust, rain, urban atmosphere such as smog and noise) and solar protection. The choice of material for the building envelopes, correct fabrication techniques and good quality systems are important to ensure that the structures are protected from outside elements and function at their best.
Façade design engineering and modelling integrates the aesthetics of the built form with the technical; to bring the architect’s vision to life and deliver a high performance building envelope.
Various studies include wind pressure, structural analysis, sun path, daylight analysis, thermal modelling, wind rise and acoustic design are all carried out during the design phase to ensure that the façades are structurally safe, to optimise the utilisation of daylight, to design the occupant’s comfort during annual weather cycle and to minimise sound transmission from outside.
Virtual design tools such as 3D modelling and simulation such as Building information Modelling (BIM) are being increasingly used to integrate the design processes and interactions between designers in the architect’s office, façade consultant and the façade contractor. It allows any aspect of a design’s performance to be simulated and assessed before it is built — helping to understand the design more completely and much earlier. The virtual prototype becomes a reference for construction. The directors of Glass Wall Systems, JawaharHemrajani and Kamlesh Chaudhari, say, “In India, constructions with heavy envelopes have dominated most of the history of architecture. Brick masonry which is not as vastly used as before was the sole element used extensively for strength, water tightness and thermal protection of structures. Its shortcomings with regards to its load-bearing capacity and protection against heat or moisture were compensated by increased wall thickness.”
Architecture in a particular area was dominated by use of resources and materials available locally. The gradual progress in terms of new construction methods and materials together with industrialisation has fostered the evolution of new systems which are high on technology and technicality.
With fast urbanisation, the use of new materials such as iron or concrete, glass and aluminium opened up new possibilities, as a result the ‘architect-artist’ of earlier centuries was transformed into the ‘architect-engineer’, to develop systems and structures which provide high performance.
RajanGovind, director, BES Consultants, says, “There is no one solution that fits all buildings. We evolve the design within the given conditions and create possible design solutions to meet expectations and owner’s desire. Appropriate material selection is a design process based on collective decisions on aspects like functional, aesthetics, economics and life cycle.”
The directors at Glass Wall Systems say that the corporate sector in India in the recent past have been typically flexible to experiment with new concepts such as double skin façades, active façades, passive façades, double envelope, double skin curtain wall, supply air window, ventilated façade, multiple-skin façade, etc. Thus the future for new materials in façades along with new systems looks bright as India makes the shift in terms of culture, exposure and expertise.
SiddeshRaikar, head (structural engineering department), Façade India Testing, says, “Complexities of design vary from project to project. In one of the projects we bagged, we were asked to create an atrium skylight. The skylight had a span as high as 20m and spanned between two towers having odd shapes. Both the towers had different building movements due to seismic and wind. The odd shape of the skylight was making it difficult to accommodate the atrium. We took care of this by providing elastomeric bearing at one end and pinned it at the other end. The elastomeric bearing was designed in such a way that it could move freely in any direction up to 100mm and could rotate while restricting uplift due to wind pressure.”
Govind says, “We will try to break any complex design into a buildable solutions. That is how we successfully completed Mondeal Square at Ahmedabad. In this project we conceived a buildable solution of curved metal screen of the complex building geometry by using 3D design techniques. Without this approach, it would have been impossible to implement the particular architectural design intent.”
Prevalent among façades today are rain screen assemblies and doublewall systems. There’s an increased concern with healthy buildings that are free of dampness and mould and this makes water-tight façades more important than ever. Double-wall systems are another way to increase performance.
These layered exterior wall systems have the ability to reduce solar heat gain by shaping building apertures and creating layering arrangements. These layers can be perforated or even translucent, providing light and view without direct sunlight. Whereas horizontal sunshades work well on south-facing exteriors, projected vertical screening works best on west-facing walls, and double-skin walls are an excellent way of achieving this type of vertical screen.
Glass technology has evolved and various types of glasses are now available. The selection of glass is dependent on strength and safety requirement, light, heat and sound performance. Annealed, heat strengthened or fully tempered glass can be used as single lite, double glazed units (DGUs) or laminated depending on the requirements. Glasses are now available with high performance coatings which balance visible light transmission and solar heat gain.
It’s a good idea to use less expensive glass as a result of this screening, although that decision would be complicated by several factors, including heat loss or gain through conduction, as well as the need for acoustical control in noisy areas and neighbourhoods. The glazing decision can be a real balancing act. Insulated glazing is a good way of building altogether that one shouldn’t consider moving toward monolithic glazing.
While façade consultants are experimenting with a whole lot of materials, SubhenduGanguly, MD, AluK Building Systems says that it’s important that one makes a façade safe. “Structurally, the façade should be safe, rigid and be able to withstand the design load of wind loading and earthquake.”
The façade is like the skin of the building. Just as the skin protects the body against external environment, the façade is supposed to protect the building in the same way. “Unfortunately, in some areas you still see a façade made of single glazing. I don’t understand how a single glaze façade can take care of the energy efficiency of the building. That means the building is in distress. It has to be energy efficient, has to be air and water tight, and all in keeping with the architectural intent of the building for which you are designing,” adds Ganguly. For that matter, double skin façades increase the performance of a building envelope. It offers a reduction in energy consumption by minimising solar gain through the façade and reduces the cooling loads of the building. Since it has the protection of an external skin, natural ventilation through the cavity can be achieved whilst not compromising on occupants comfort during harsh climatic conditions. Besides acoustic insulation, occupants can control light penetration and regulate air movement and temperature with operable windows.
Simultaneously, there is an increased use of GRC (glassfibre reinforced concrete) material in façades. Besides this, there are some new products like porcelain, tile cladding and other clay tile products that could be considered as new trends in façades. However, there is a consensus among some façade consultants that there is no equivalent for aluminium composite panels. Some projects have been recommended with solid sheet cladding material since they are fire-resistant and also give a good finishing look in terms of flatness on façades. Zinc, copper and other metal cladding material are not so highly recommended in view of the environmental conditions in India.
However, Rajeev Antony, MD, Schüco India, says, “If we look at aluminium systems, they are the perfect material choice for façades since they are highly reliable and provide options for varied designs. Aluminium is a proven material world-wide for its performance and this forms the base for high rise façades, structural and varied façades.
It also meets numerous aesthetic and design concepts by architects. Surface treatments such as powder coating, anodising and PVDF (polyvinylidene fluoride)make aluminium a versatile option that cannot be substituted by using any other material.” The directors at Glass Wall Systems say that with the evolution and advancement of technology, architects and consultants are not shy to explore innovative design options and experiment with materials. This could include metals such as bronze, cast aluminium, cast iron, expanded metal, embossed copper, glass for variable light transmittance processed as laminated or DGU, composites like aluminium, copper asphalt, and stone such as granite, ceramic tiles, terracotta, sand stone and marble. “We provide room for architects and consultants to think beyond contemporary methods.
Our team is capable of designing the best system solutions that meet the requirements of the project at the same time keeping the clients budget in mind. Innovation using new materials and systems has been the trademark for Glass Wall Systems with media façades, green façade, window wall and up-comings being some of the achievements in the past,” they add.
Ganguly of AluK says that solar façades are also catching on. “The Indian Green Building Council (IGBC) is also taking initiatives. Apart from that, we often see a requirement for ventilated façade and double skin façade.” The building envelope’s main function is to act as a filter between the exterior environment and the building indoors. But as technologies have evolved and the urgent need to reduce overall energy consumption has grown, the role of the envelope has now become more complex.
It has to guarantee that the necessary interior climate conditions can be maintained during the whole year with low energy requirements. The concerns that high performance envelopes must address are: insulation, conduction, solar radiation control, infiltration (air tightness), openings and daylight. Energy performance will be determined depending on how these issues are approached:
• Project pursuing LEED rating normally has an energy modeller on board who carries out comprehensive analysis on energy savings from all packages including civil, HVAC &MEP, façade, landscape, etc.
• The requirement related to façade are governed by U value and shading coefficient of the fenestration system and the use of materials which have more recycle content.
• Façade glass properties form animportant aspect from LEED assessment and normally kept above or at least matching to properties specified in LEED report.
• Infiltration is just not allowed since it accounts for 30-50% of the heat lost or gained in structures that are not completely airtight.
• Regarding use of recycled materialsin façade, project specific declarations can be obtained from respective suppliers specifically for materials like glass, aluminium, glasswool and sealants.
• Preference is given for materials available locally as it reduces transportation.
With ecologically sustainable development being the most important guideline in residential and commercial buildings, developers are looking at comparatively eco-friendly building materials and ceramic tiles comes out as a better option to them. Although ceramic tiles have been used as cladding material for façades for ages, with improvement in technologies, they are considered more sophisticated cladding material with great class of aesthetic appeal. The ceramic tiles available in the market have graduated from the old days of clay roof coverings; they are now available with hundreds of qualities.
For cladding and façades there are non-porous, scratch proof ultra-vitrified tiles available in the market. Those architects who deal with ceramic tiles have come up with many innovative methods where it can be used for claddings.
An innovative method gaining importance is chambered tile façades where tiles are not put on the surface of wall; rather an air chamber is created between wall and the tile cladding. This protects building not only from rain, sunrays and chilly weather; it also regulates the temperature very efficiently and effectively. This also eliminates problems like seepage and algae. A benefit here is that in case of need one can always change the tiles easily as and when required.
A sustainable façade system also protects the building from fire. It acts as a fire alarm and gives at least a time of two hours to vacate the building in case fire has spread inside the building. Antony of Schüco India says, “Non-insulated unitised façades are gathering speed in India. Unlike the passé mind-set of using any local aluminium, accessories and hardware and setting up their own fenestration, people are looking for high performance non-insulated façades and that’s where we come in with our global expertise to bridge the gap. Schuco supplies high quality, reliable systems to the benefit of developers and end clients. We have developed TropTec systems which is a range of aluminium doors, windows and façade systems especially designed for Indian tropical and urban climatic conditions.”