Passers-by may admire aluminium systems on windows. But few know about its energy efficiency, and acoustics performance
By JAYASHREE MENDES
A primary challenge that architects in building design face is ensuring that windows and doors maintain the integrity of the interior environment
by meeting the established national standards for energy efficiency and acoustic performance. Yes, there are stipulations and they have to be met.
Traditional architecture stuck to small windows as the concept of air-conditioning was not a necessity. Modern architecture has changed building design drastically. “Generally, an entire building envelope is as good as a window as it allows light to penetrate into the building. And with air-conditioning now a necessity, the function of ventilation cannot be stressed upon enough,” says Harish Gupta, vice-president, architecture, Glass Wall Systems.
No more are windows confined to being just windows. That they ensure air-tightness are the need of the hour, since the increased use of AC units for cooling and heating is resulting in increased energy cost. During winter in India, air-conditioners are hardly utilised with electric heaters
taking its place. But unfortunately, the generated heat dissipates quickly and the solid concrete walls continue to remain cold. Then there is the fact that often daylight seeps in through the frames and the joints.
Climate and topography plays an important part in deciding fenestration design and type. Windows/fenestration should be capable of reacting to non-continuous, changing external (weather/urban) conditions. “Following the same principles, we have designed TropTec range of products that are made specially for Indian climatic and urban conditions. The systems have been designed after much research on Indian market, topography and climate. The fitment of our products is spot-on with excellent performance deliverables when it comes to wind resistance, water tightness and structural stability, typical of a German engineered product,” says Rajeev Antony, managing director, Schüco India.
Schüco has systems for doors, windows and façades designed specially for tropical climate zones; these non-insulated systems are ideal for a wide range of commercial and residential high-rises, and private homes across India.
Every region experiences a different climate and “generally glass will be selected as per the climate in that region. For example in tropical countries that see plenty of sunlight, the coating on the glass is used to prevent excess sunlight inside so that air-conditioning use is minimised. On the other hand, countries seeing a cooler climate will have more sunlight penetrating inside to minimise heating requirements inside the buildings”, adds Gupta.
For a tropical climate like that of India, Anjan Putatunda, general manager, Alcoa India, advises, “It is better to have more open area per window, and the windows should be placed across the ventilation. Medium-size doors and windows are recommended for a tropical climate.”
One material that has stood out for its high quality seals and has received approval from the industry and users is aluminium. It meets the industry’s expectations for energy efficiency, acoustic performance and weather proofing, while also improving their buildings’ green ratings. “Aluminium windows save energy after careful selection of glass. Windows are designed as per architecture of a building and the orientation as per sun rays plays an important role in energy savings and internal comfort. When using aluminium as frames, one must keep in mind to minimise exposure
of the metal to direct sunlight as much heat transfer takes place. Design needs may make it necessary for glass to completely overlap the metal or use thermal breaks to restrict heat transfer to internal environment through the metal,” says Gupta.
Aluminium windows started in the early 1990s much before
uPVC (unplasticised polyvinyl chloride) windows entered the arena. Thanks to the surge in the construction industry and rapid industrialisation and modernisation of airports in India, a number of global players especially dealing with aluminium products have stepped into the Indian fenestration
industry. So when uPVC came in, there were constant comparisons drawn between the two materials in terms of strength, performance, cost-effectiveness and eco-friendliness.
Aluminium scores with its numerous advantages of high strength to weight ratio (making feasible light structures with innate stability), design flexibility (its extrusion enabling numerous range of forms) and its durability, while alloys of aluminium make it efficient for light management and are corrosion-resistant and immune to the harmful effects of UV rays. It has an easy maintenance (a mere routine cleaning is required) that leads to lots of cost savings over the product’s lifetime. Other advantages with the material are its environment-friendly nature, various colour as well as finishes availability. Mumbai-headquartered Hindalco Industries Limited, the market leader in aluminium, offers quality aluminium windows under their brand ‘Eternia’. It contains three sliding and three casement systems from Italy with different typologies (such as external/internal opening, pivot, top hung, tilt and turn, etc for casement systems and two-track/three-track, with fixed frame for sliding systems and mosquito
mesh system). Fine quality hardware and accessories (sourced from renowned European companies) ensure effective functioning of the windows.
Windows should not only aesthetic appeal, but importantly serve their purpose of durability, operation and comfort. Energy saving is an inherent feature of a well-designed window system which insulates the inside from the outside thus keeping the energy requirement at a minimum. “They provide better insulation (thermal, acoustic and environmental) owing to the options of double or even triple glazing combined with thermal breaks. It is key to have well-designed & tested systems for comfort when it comes to reducing the noise levels,” says Antony.
Over the years, technological advancements have enhanced the design of fenestrations and also stepped into the management part of their logistics. Poring over excel sheets and faulty quotations would lead to trouble for the fabricator (thus leading to problems like raw material wastage, errors in profile calculations, etc) . Currently, most fabricators prefer to use versatile software that attends to all the concerns associated with precision and provides up-to-date information for analysis and decision making.
Environmentally-friendly is another aspect that any material used in modern buildings must consider. For instance, buildings are prone to fires and various hazards. So how can one ensure making windows fire-proof? ‘Fire-proof’ is an ambitious term to use, says Schüco’s Antony. “Most products
are ‘fire resistant’ at best and are classified according to the certificates they have been accredited with after rigorous testing. On case and need basis, we can make available complete aluminium systems to fulfill the numerous fire and smoke protection requirements, which are extensively used in Western markets. These systems, tested according to the highest German and European standards for fire and smoke protection and then certified, will satiate the needs for tall buildings in terms of fire and smoke resistance.”
Kawneer’s Putatunda has a different kind of offering. He says, “We have Reynobond which is a composite panel consisting of two coil-coated aluminum sheets permanently bonded to an extruded thermoplastic PE or FR (fire retardant) core material. Reynobond is suitable for architectural applications due to its flatness, its light-weight (in comparison to steel and solid aluminium), and its ease of fabrication.” Another product that the company has is Reynolux, a coil-coated aluminium sheet used for roofing, wall cladding, roof windows accessories and sun protection.
Aluminium’ is a highly tried and tested material for windows and facades. It can be extruded in virtually any size far more versatile than any uPVC window system. Since the performance depends on the design and integration of the system, a well-designed system will live as long as the building structure itself. Due to a variety of finish, aluminium can offer aesthetic appeal. The general application of aluminium is in long profiles and so it gives a very sleek look to the façade and windows compared to conventional material. Moreover, the material does not need recoating as often as traditional materials and so it is virtually maintenance-free.
In the absence of any industry standards, the aluminium windows market has its share of problems too. “It is a heavily fragmented segment, and in the absence of any regulatory body and industry standards, there is much left to be desired in the quality of aluminium windows. The concept of branded aluminium windows is not as strong in India like in the US, UK and Europe where there are several established brands. However now branded aluminium windows have started entering the Indian market and when branded products are available, one is certain that some science has gone into designing and developing these window systems and that there is consistency in quality.