Glass is one of the most overused structures in modern day architecture. What started as a trend decades back has now become a symbol of progress. Major cities around the world have switched to the glass as a building material and have continued the trend at unrelenting speeds. Our obsession with looks implies that glass facades will continue to exist for many more years to come.
Glass has been a part of even the so-called sustainable architecture. Architect Ken Shuttleworth built a giant building 14 years back famously called “The Gherkin” in London. The building was made of glass and was an epitome of architectural capability at the time. However, the same architect, like other urban planners, has come out openly against using glass in construction. He feels that we cannot have all-glass structures anymore as we need to be more responsible towards the environment. He believes that glass buildings are energy-spots, and we have to find an alternative source of energy efficient ones.
What makes Glass so popular?
The proliferation of Glass as a building material began mostly after post-war improvements in glass technology. Energy at that time was cheap and thermal efficiency of glass didn’t matter much because air conditioning came at a cheaper cost. Slowly other benefits of glass emerged. Glass is an easy to produce material (especially now with more technological advances). It can be manufactured faster and with greater uniformity. Compared to other materials, glass is relatively lighter. This means lesser stress on the building foundation and lesser overall weight of the building.
Glass buildings look stunning once completed. The floor-to-ceiling windows let a lot of natural light in and provide amazing views. Glass also requires very less maintenance. With more progress, we’re now able to produce glasses with greater durability and strength. The overall cost of constructing a building comes down greatly with the use of glass.
Why is Glass not suited anymore?
Things were different once upon a time and climate is now changing faster than we anticipated. We are at a stage where we cannot anymore ignore how energy inefficient glass is. Glistening skyscrapers made sense in colder countries where glass was used to trap heat and beat the chilling winters. But what is shocking is the rampant use of glass in hot/tropical places like UAE, India and other South East Asian countries. In countries like India, the appearance of the building now takes a backseat in the choice of building material. Glass is used to fasten the construction process and reduce costs considerably.
So what makes glass unsuitable? Answer – a lot of things.
- According to the United Nations, 40% of the world’s energy consumption and one-third of greenhouse gas emissions are attributed to buildings. It’s a matter which needs to be addressed with extreme urgency.
- Glass scatters a lot of light and causes illumination. Under sunlight, structures with inward curves act almost like a huge magnifying glass, capturing concentrated sunlight. Some 5 years back, the famous 37-storey Walkie-Talkie building in London reflected so much light that it melted a few cars parked opposite to it. In the end, the makers had to spend an extra amount to install sunshade for the building. Building a structure using glass and then covering it with a sunshade doesn’t make architectural and economic sense.
- Glass also causes glare. To prevent absorption of heat, the glass surface is often coated with a reflective paint. This causes glare, unwantedly illuminating the surrounding and heating them in the process.
- Glass is thermally inefficient. Let’s say you use 3 panes of glass instead of one to reduce glare (known as triple glazing). The triple glazed glass will still have a U-value of around 1.0 (U-value measures the amount of heat lost through a given thickness of a material). Compare this with 0.35 U-value of a simple brick or 0.1 U-value of a properly insulated wall. Glass does little to trap heat on cold days but turns the building into a burning cage during summers. To beat the heat, we install more air conditioners – which in turn heat the outside of the buildings and emit greenhouse gases in the air.
- Glass buildings heat the surroundings. With more and more people living in the urban areas, glass buildings damage not just the immediate surroundings but also alter the weather of a city. They dump in a lot of heat in the environment. Years back, when Britain experienced its hottest June in 40 years, the Committee on Climate Change attributed this to many key factors including glass structures. They said that the buildings that we built to date become too hot in soaring temperatures and are a hazard for future generations.
What lies ahead?
Technology has grown by leaps and bounds in the past few decades. We have come up with options of tinting, glazing or coating glass buildings to reduce heat loss (during winters) and solar gains (during summers). However, replacing glass with some other energy efficient material makes more sense. More air conditioners = more electricity consumption and this cannot be the go-to solution to tackle heat. Ventilation is as important as natural light. It is important to strategically construct windows in a building to reduce the need for air conditioning.
Traditional thick brick walled buildings are way better than glass buildings. If not a complete replacement, then glass should be used in conjunction with other materials. For e.g. use glass where light enters and there is a view and use other materials otherwise. Even with all the possible solutions charted, Shuttleworth and other architects believe that glass will continue to be indispensable for a long, long time.
Human and the Climate 