In the current economic crunch, architects and designers are considering plastics for certain applications in order to cut costs, but a recurring question is whether it is an environmentally friendly option.
Christo Pienaar, marketing director of the Ampaglas Plastics Group, says, “The perception is that glass is the more eco-friendly option because it is seen as a ‘natural’ product. But sustainability and eco-friendliness are dependent on a number of factors besides biodegrability.”
Pienaar points out that to make glass, a high-powered oven is used at a temperature of 1500°C or higher. All this heat means high levels of energy consumption and results in a substantial amount of CO2 being released into the atmosphere. Some calculations – factoring in the transport of glass, which is a relatively heavy product – indicate that this could be as much as two tons of CO2 per ton of glass.
He cites a Carnegie Mellon University study which shows that glass consumes nearly two times more energy during production than plastic, produces three times more air pollution than plastic, and seven times more global warming gases than plastics. He also highlights that sand mining is seen as ecologically damaging.
Plastics are a popular material for skylights because they are lightweight, so they don’t add to the structural load of the roof, and because they are durable. On choosing the right plastic, Pienaar says, “We usually recommend polycarbonate because, in addition to its high-impact strength, it provides the best clarity. Acrylic sheeting has a higher UV-resistance but will scratch more easily, and polypropylene is the cheapest option but the least clear and most likely to expand.”
Polycarbonate is also often used to make bus shelters and street furniture that may be vulnerable to vandalism and graffiti. Pienaar emphasises the material’s design benefits. “Plastic can be moulded into any shape or form and it is available in a variety of colours. This gives designers a degree of creative freedom.”
