Building Right With Glass

Ar. Nilabh Nagar, Senior Associate Architect at Architect Hafeez Contractor, has, over his 26 years of professional practice, handled diverse typology of buildings.

Ar. Nilabh Nagar, Senior Associate Architect at Architect Hafeez Contractor, has, over his 26 years of professional practice, handled diverse typology of buildings, including office buildings, shopping malls, individual residences and group housing.

His recent works include heading the work of the domestic airport terminals of Mumbai (T1C) and Delhi(T1D), being part of feasibility and concept design teams for VT Railway development and Mumbai Airport master plan, and several Green-rated buildings.

With his keen interest in energy conservation in architecture, building technologies, and innovative materials, he tells Ar. Apurva Bose Dutta why he thinks glass as a material should not be criticised.

Apurva Bose Dutta (ABD): In times when discussions on architecture and urban design revolve around sustainability and going green, glass has come across as a controversial building material in the Indian context. As someone who works on green building design and with glass to a large extent, what is your take on it?

Nilabh Nagar (NN): There is a lot of misunderstanding around the use of glass. The indiscriminate and irresponsible use of glass has resulted in buildings with larger energy consumption. However, that does not mean that we criticize the material.

Glass has very distinct endearing qualities, which can greatly enhance living spaces and human habitations, as well as the aesthetics of buildings. It allows transparency, ensures daylight and greater visual connectivity.

It also allows heat to permeate through, and hence, in our climate, needs to be adequately shaded to ensure minimal heat ingress.

It can also cause glare which can be controlled by the use of tint and coating. I think the advantages far outweigh the issues around it.

In my opinion, ‘green’ is a very misunderstood word. Are we talking here about green ratings or are we talking about energy-efficient buildings? It is true that excessive use of vision glass brings in heat.

But then, one has the option to have full glass buildings with varying amounts of vision glass, based on orientation and shading elements to maintain appropriate balance between light and energy.

The use of technology has given way to double glazing and coatings on glass which can attain the U-value equivalent to that achieved in a brick wall. Double skin ventilated facades can also achieve the same U-value, though at a higher cost.

ABD: In your 26 years of professional practice, what changes have you noticed in the thought processes of architects as well as the users when it comes to using glass as a building material?

NN: The appearance of glass buildings is rich and glossy. The imagery associated with it makes them appear modern and high-tech and therefore, aspirational to the larger crowd. However, badly designed faceless glass boxes have lessened and today, the trend is towards achieving a balance between glass and solids.

Glass has also become the material of choice for partitions in the interiors. Due to its ease of maintenance, it is increasingly being even used as a cladding material and in railings too. The more prominent architects today have become far more responsible in the appropriate use of glass for effective daylight, colour, texture and transparency.

ABD: Your major projects include the modernisation of the international terminals of the New Delhi and Mumbai airports. Could you mention the innovative use of glass in these buildings that has made a huge difference to their design?

NN: For the design proposed for the New Delhi airport terminal, glass was used in both the façades, facing the airside (to ensure far-reaching extensive views to the apron) as well as on the landside for passengers to assimilate views of the interiors of the terminal. The open terminal design has the clear view of the airside from the landside and check-in counters, thereby allowing a clear sense of direction and space. The commercial needs however overcame the design solutions that we had proposed, and I understand that now most of the views are for retail outlets.

In case of the Mumbai airport terminal, we designed the glass only on the airside. This curved inclined glass façade on the airside with aluminium fins has been specifically designed to reduce direct sunlight on the south façade without mitigating the views.

ABD: Architects have married glass with superior technology overseas to produce designs and results that have brought revolutions in architecture. Can you recollect a few buildings whose creative and logical use of glass has impressed you?

NN: There are a lot of projects overseas where designers have made brilliant use of glass. The Apple Store on the 5th avenue in New York used glass as a structural element, perhaps for the very first time in history. The Louvre Pyramid is a great innovation in glass where the entire glass has been held in a way so as to make it appear very light on the eyes. It is a great example of how despite its geometric form, the transparency and reflectivity do not disturb the heritage feeling of the Louvre Plaza. There are other buildings which have implemented glass very innovatively, such as the Tower of London which uses glass tubes as compression elements, the Kempinski Hotel at the Munich airport that has a free-standing cable net glass wall allowing transparency between the hotel and airport. More recent examples include the roof of the Milan trade fair with a glass canopy whose scale is fantastic, and the Innsbruck train stations with a double curved glass used in cladding.

ABD: What are the technological innovations that you would like to see in glass in the near future?

NN: Unbreakable glass with transparency but no heat ingress would be wonderful to work with. It would also be nice to replicate the properties of the photochromatic glass we use in spectacles in architectural glass. Presently, the use of photochromatic glass in glass buildings faces the challenge of high cost factor.

ABD: Glass buildings are expensive. How do you take care of the cost factor of such buildings?

NN: Market forces automatically take care of that! Also, I believe that with time, we have become more responsible with our design and resources. The use of wrapped glass in commercial buildings is really dead, except maybe in the smaller towns where people are more desirous of aping the West and the metros; but then, that is only a small percentage of buildings we are talking about here. In metropolitan cities, especially the buildings of IT Parks, clients have developed energy consciousness and hence they use limited amount of glass, probably around just 30%–40%. New materials such as terracotta, acrylic solid surfaces, metal and chromatic back painted glass are being used in combination with regular brick mortar to make buildings look more interesting. In residential buildings, however, the proportion of glass has been quite constant.

ABD: Please acquaint us with some of your recent projects where glass has been used in a radically different manner than earlier?

NN: We have recently proposed the use of chromatic glass on the façade of a building in Ahmedabad. We have also proposed the use of metal laminated glass in another project with expanded metal embedded in glass replicating a metal jaali. For this, we have collaborated with a company from Germany who has given some interesting metal patterns which bring a certain gloss as well as privacy to the glass building.

In another project in Kolkata, we are proposing the use of extruded glass as screen wall for back lighting and as rafters under a skylight.

The building of Taj Santacruz behind the Mumbai International Airport terminal that we completed in 2016, has a double skin façade. The first layer is a triple laminated clear glass used in the windows and the second layer is a high-performance green tint laminated glass in the curtain wall.

Here, glass serves multiple uses — firstly, visual; secondly, acoustic (achieving a reduction of 50 decibels) to ensure that the guests are not disturbed due to the aircraft noise, and thirdly, security with the use of laminated glass specially designed for the security requirements of airport hotels.

In the Bharti Airtel building at Gurgaon, we have again used glass as a double skin laminated glass façade to enhance the brand image. We have endeavoured to create a landmark by specially ordering lamination to match the company colours.

Ar. Apurva Bose Dutta is a Bengaluru-based architectural journalist (www.apurvabose.com) and is the Architecture & Design Content Partner at Saint-Gobain India Pvt Limited–Glass Business.