Plastics and the construction sector: the incarnation of high technology

Since their appearance in the construction sector, polymers have seen it all. They were proudly put on display when initially considered as the pinnacle of modernity in the 1960s. Today, they are more discreet and have improved their energy performance.

The 1960s: polymers, the pinnacle of modernity

In the late 1960s, plastics were clearly perceived as resolutely high-tech materials. Some believed that the plastic utopia signalled the end of so-called traditional materials, in particular wood and glass, and the future would prove them right, in part. Some architects had a very futuristic vision, such as Finnish architect and designer Matti Suuronen who would step into the limelight in 1968 after designing the Futuro, the first plastic house. Inspired by UFOs, which were a very fashionable topic during this period focused on the conquest of space, the house was a 4-metre tall cake-shaped structure with a surface of 36 square metres. Made from fibreglass-reinforced polyester, the Futuro house was also fitted with plastic furniture. Its success was as unexpected as it was immediate. The ease with which a polymer such as polyester could be molded meant that the prototype could soon be mass-produced. In the end, around one hundred copies were produced in various very fashionable colours such as yellow and orange. More than ever before, plastics became the symbol of a modern and pleasant world. Unfortunately, its strong “flower power” connotations and the oil crisis of the 1970s would sound the death knell for the Futuro.

The  Futuro House symbolises the plastic utopia of the 1960s and flower power. This plastic house was perceived at the time as being the quintessence of modernism.

It would be forty years before plastic houses would once again make their appearance. Green Magic Homes, an American construction company building individual homes, offers to build home identical to those inhabited by the Hobbits from Lord of the Rings. Sold as modular components, these original homes comprise a structure made of polyester reinforced with various fibres which can then be covered with soil and greenery to turn it into your very own Hobbit hole. The structure is both water and fire resistant and is non-toxic. The manufacturer also offers a choice of colours for the façade (stone or sand, for instance) so that the houses can better blend in with the surrounding landscape. Because the houses are sold as prefabricated modular components, it only takes a week to build a three-bedroom home. Finally, and this is possibly one of its main benefits, the double layer former by the polymer and the soil acts as an excellent insulator.  

Living  like Bilbo the Hobbit is no longer a fantasy. Thanks to their structure made up of fibreglass-reinforced polyester, the Green Magic Homes are designed to be buried.

Insulation: polymers do a fine job If there is one field in which plastics have nothing to prove, it is that of sound and thermal insulation. In the first case, polyurethane foam is the clear leader. A material which has been around for decades, it is still irreplaceable or at least unequalled, as much for its formidable insulating properties as for the ease with which it can be installed and its relatively low cost. There are many methods for insulating a building: double or triple glazed windows, plugging up thermal bridges and good insulation ranging from revisited cob to materials that have already proven their worth such as expanded or extruded polystyrene and resolutely modern materials such as Neopor©, a revolutionary material developed by the German chemicals company BASF.

Thanks to polymers, great progress has been made in insulating renovated buildings since they can be insulated from the outside without reducing the surface of the living spaces inside.

Simply put, it is a derivative of its cousin, expanded polystyrene enriched with graphite. It is one of the most insulating materials currently available on the market. Its capabilities come from the graphite particles it contains which reflect heat radiation like a mirror, thus reducing heat loss. This is how it achieves the same insulating capabilities as materials that are six times thicker, such as rock wool, despite using fewer raw materials. Another advantage it offers is that it is suitable for indoor and outdoor use. In just a few years, it has become the preferred material for renovations and new builds, particularly when they are passive buildings. In addition, it is fully recyclable and its manufacture limits greenhouse gas emissions since 98% of the material’s composition is air, the remainder comprising pellets of material expanded by injection of water vapour.

A polymer film to keep a cool head

Although the first step in improving a building’s energy performance requires insulating the walls and roofs and systematically installing multi-layered glazing, our world contains a number of paradoxes. Modern buildings, which are extremely well insulated from the cold, are often fitted with energy-inefficient air conditioning systems designed to keep their occupants cool. Polyester or PET films which can be metallised to provide a mirror effect and which can be applied to windows were developed many years ago. They reflect light and heat and often block UV rays. They are fairly effective, but activating the air conditioning system is often required when temperatures reach 30 °C.

The potential applications for the polymer film to be applied on windows designed by MIT seem infinite. The project is still at the research stage, but if objectives are met, it could reduce the heat in an apartment or office by several degrees.

It is estimated that around 1.6 billion air conditioning systems have been installed around the world, and that 135 million additional air conditioning systems are sold every year. According to a report of the International Energy Agency, the demand for electricity due to air conditioning will triple by 2050. In practical terms, if nothing changes, it will be necessary to produce as much electricity as China consumes in order to power all the air conditioning systems around the world. The machines will also emit one billion tonnes of CO2 per year, which is equivalent to the emissions put out by the entire African continent. American researchers at MIT recently developed a new type of transparent film that can be applied to windows which is able to repel 70% of the heat, thus reducing the inside temperature by up to 9 °C. The researchers used a polymer already known for its thermochromic properties which bears the unpronounceable name of poly(N-isopropylacrylamide)-2-Aminoethylmethacrylate hydrochloride, a material that changes colour when the temperature rises. This polymer had already proven itself with regard to filtering light; however, its small molecules let through the infrared rays responsible for heat. The MIT researchers innovated by increasing the size of the molecules without affecting the polymer’s properties. The larger molecules block the infrared rays and therefore the heat that they generate.

The cushions made from ETFE films which elegantly cover the Media Tic building in Barcelona are not just decorative. When temperatures rise, they are inflated and block the rays of light, ensuring that the building’s occupants remain cool.

Plastic cushions to block heat Ethylene tetrafluoroethylene, better known as ETFE, has quickly managed to become a must-have material for many buildings. We reported on it last year in an article on football stadiums. It is true that the polymer has something magical about it: in addition to its strength and the ease with which it can be recycles, it provides an elegant and transparent covering for any building.

In Barcelona, in Spain, the architects at Media Tic, an office building, designed cladding composed of an assembly of ETFE cushions. Fitted with light sensors, they are inflated like an inner tube depending on light levels and heat. When they are inflated, the cushions’ envelopes overlap and block the rays of light. In addition, the air stored inside the cushions acts as thermal insulation and protects the building’s occupants from the heat. The architects who designed the system believe that a saving of around 20% could be made on air conditioning, which is considerable in a region where temperatures easily reach 30 °C in summer.  

This being said, covering a building in plastic is nothing new. Wooden constructions are extremely common in the United States, and Americans value them highly. It’s a cultural thing! Although pretty, wood has a major drawback: it requires a lot of maintenance. As a result, many homes are designed with a cladding usually made from ABS, an ultra-resistant polymer that can take on any colour and which perfectly imitates the grain of wood. Its other advantages include the fact that it is rotproof, fungicidal and recyclable.

Sober concretes thanks to polymers

Concrete is a mainstay in the construction sector, especially for large buildings. However, its environmental impact is far from neutral. Producing concrete requires cement, which can only be manufactured in furnaces operating at very high temperatures (around 2,000 °C). In addition, in order to act as a binder, cement requires very large quantities of water, a resource that is far from inexhaustible. Upon adding polypropylene or polyamide fibres to the concrete, construction professionals noticed that it was strengthened and more flexible, but also that it required less water to manufacture because the fibres act as an additional binder which does not need to be hydrated. The water/cement ration decreases from 0.45 to 0.60 for an ordinary concrete to 0.30 to 0.40 for this new type of concrete. Christened UHPFRC for Ultra-High-Performance Fibre-Reinforced Concrete, it is widely used in the construction of individual houses.

This concrete paved the way for many more innovative applications, and some forms even let light through. Their secret is that they contain a network of optical fibres most often made from PMMA (polymethyl methacrylate). Generally molded into more or less complex shapes in factories, these concretes are still mainly used as building cladding. The effect is visually stunning, as the cladding lets light through during the day and creating interplays of light and shadow. When night falls, it becomes phosphorescent and can even change colours depending on the colour of the light source.

Designed by a Hungarian architect, LiTraCon is a concreted into which optic fibres have been inserted in order to create impressive lighting effects.

Solar panels get a makeover In order to maximise their effectiveness, silicon solar panels have to be tilted at a 30° angle from the horizontal plane. Quite a constraint for architects seeking to integrate them into a construction project. Additionally, black solar panels are not the most aesthetically-pleasing. Sunpartner, a recently incorporated French company, has just revolutionised the field by creating coloured panels that are effective in a vertical position.

Sunpartner’s Wysips solar panels are effective even when placed in a vertical position. The innovation lies in the fact that they can be dyed to better fit in with a building’s appearance. A first!

A technological feat which required the filing of 150 patents! Sunpartner uses CIGS cells (copper, indium, gallium et selenium) which are able to capture electrons regardless of their position relative to the sun. This technology is not new and its yield is slightly lower than that of silicon. However, it is relatively easy to manufacture and can be applied, like an ink, onto a glass or plastic surface. However, the cells had always been black to date. Sunpartner’s innovation lies in having found a way to dye them without causing them to lose their effectiveness. Solar panels can now become decorative elements or even become invisible. So much so that Sunpartner christened them “Wysips” for “What you see is a photovoltaic surface”, which says it all.