Tag: housing

A raincoat for our houses

From the use of Gore-Tex-like waterproof fabrics to the development of “breathable” bio-based materials, the construction industry is chasing breakthrough solutions to insulate buildings and keep living areas free from damp and mould

Today, one of the new challenges for the construction industry is the use of textiles, coming from the clothing and footwear industries. Gore-Tex-like membranes, which are usually found in weather-proof jackets and trekking shoes, are now being studied to build breathable, water-resistant walls. Tyvek is an example of one such synthetic textile being used as a “raincoat” for our homes.

Camping tents, which have been used for ages to protect against wind, ultra-violet rays and rain, have also inspired the modern construction industry, or “buildtech sector”. This new field of research focuses on the different fibres (animal-based such as wool or silk, plant-based such as linen and cotton and synthetic such as polyester and rayon) in order to develop technical or high-performance materials, thus improving the quality of construction, especially for buildings, dams, bridges, tunnels and roads. This is due to the fibres’ mechanical properties, such as lightness, strength, and also resistance to many factors like creep, deterioration by chemicals and pollutants in the air or rain.

“Textiles play an important role in the modernisation of infrastructure and in sustainable buildings”, explains Andrea Bassi, professor at the Department of Civil and Environmental Engineering (DICA), Politecnico of Milan, “Nylon and fiberglass are mixed with traditional fibres to control thermal and acoustic insulation in walls, façades and roofs. Technological innovation in materials, which includes nanotechnologies combined with traditional textiles used in clothes, enables buildings and other constructions to be designed using textiles containing steel polyvinyl chloride (PVC) or ethylene tetrafluoroethylene (ETFE). This gives the materials new antibacterial, antifungal and antimycotic properties in addition to being antistatic, sound-absorbing and water-resistant”.

Rooflys is another example. In this case, coated black woven textiles are placed under the roof to protect roof insulation from mould. These building textiles have also been tested for fire resistance, nail sealability, water and vapour impermeability, wind and UV resistance.

Production line at the co-operative enterprise CAVAC Biomatériaux, France. Natural fibres processed into a continuous mat (biofib) – Martin Ansell, BRE CICM, University of Bath, UK

In Spain three researchers from the Technical University of Madrid (UPM) have developed a new panel made with textile waste. They claim that it can significantly enhance both the thermal and acoustic conditions of buildings, while reducing greenhouse gas emissions and the energy impact associated with the development of construction materials.

Besides textiles, innovative natural fibre composite materials are a parallel field of the research on insulators that can preserve indoor air quality. These bio-based materials, such as straw and hemp, “can reduce the incidence of mould growth because they breathe. The breathability of materials refers to their ability to absorb and desorb moisture naturally”, says expert Finlay White from Modcell, who contributed to the construction of what they claim are the world’s first commercially available straw houses, “For example, highly insulated buildings with poor ventilation can build-up high levels of moisture in the air. If the moisture meets a cool surface it will condensate and producing mould, unless it is managed. Bio-based materials have the means to absorb moisture so that the risk of condensation is reduced, preventing the potential for mould growth”.

The Bristol-based green technology firm is collaborating with the European Isobio project, which is testing bio-based insulators which perform 20% better than conventional materials. “This would lead to a 5% total energy reduction over the lifecycle of a building”, explains Martin Ansell, from BRE Centre for Innovative Construction Materials (BRE CICM), University of Bath, UK, another partner of the project.

“Costs would also be reduced. We are evaluating the thermal and hygroscopic properties of a range of plant-derived by-products including hemp, jute, rape and straw fibres plus corn cob residues. Advanced sol-gel coatings are being deposited on these fibres to optimise these properties in order to produce highly insulating and breathable construction materials”, Ansell concludes.

 

By Chiara Cecchi

21 December 2016

The Social Life of Bricks

A celebrity in the materials world, Mark Miodownik dreams of colour-changing walls and looks at the future of renewable buildings

Mark Miodownik will never forget the day he became obsessed with materials. He was a schoolboy in 1985 when he was stabbed in the London Underground. “When I saw that weapon in the police station later, I was mesmerized. I had seen razors before of course, but now I realized that I didn’t know them at all. (…) its steel edge was still perfect, unaffected by its afternoon’s work,” he writes in his bestselling book Stuff Matters.

Growing up, Miodownik turned his fixation into a successful career. He became a materials scientist at the University College London, the director of the UCL’s Institute of Making and a widely known speaker and BBC presenter. His research interests include biomaterials, innovative manufacturing, and sensoaesthetics, a science that investigates the intricate relationship between people and the materials they use.

We asked Miodownik to share his views about the rediscovery of traditional materials in modern architecture, and how tomorrow’s buildings will cross the border between new and old technologies.

 

Do you think there is still value in using wood, straw, wool, or other traditional materials for buildings?
I don’t see being “traditional” as a value per se. The choice of materials has to be assessed with modern criteria, which include sustainability and energy consumption. If you ask me whether traditional materials are appropriate for modern buildings, I think the answer is yes. Partly because traditional materials have a portfolio of properties that are sometimes better than anything we have created recently: wool, for example, is a fantastic insulator.

Partly because it’s the whole ecosystem that matters. In the old days, the building materials we used were part of the landscape, and they were easier to recycle. New materials are not usually like that. When it comes to sustainability, traditional materials are often more efficient.

 

Construction experts point to limits in the public perception. Some described the three little pigs syndrome, a misconception by which buildings made with traditional materials, such as wood, would not be not as stable or durable as concrete. Is this vision widespread? And does our cultural background influence how we perceive materials?
There is no simple answer. Anthropological studies show that different cultures favour different materials, but the ways people relate to materials is extremely complex. The texture, the feel, the colour or even the imperceptible smell of an object can affect our emotional state. The materials we choose for our house, or the clothes we wear, not only represent us are but they also change how we are. Therefore, the materials we choose for a building can have subtle social consequences.

However, I don’t think that the “three little pigs syndrome” you describe is so widespread. People generally trust the engineers and rarely think about buildings collapsing, unless they live in an earthquake zone.

Rather, I believe that the influence of the global culture is predominant. People worldwide associate concrete, glass, and steel with modernity – think of the iconic image of a skyscraper – and this cuts across many cultures, especially in countries that are switching from rural to urban.

In the industrialised countries, I see much more of the opposite syndrome: many people don’t like concrete and are looking for alternative materials to build their homes.

 

My sports shoes have a new waterproof layer and a classic leather upper. Will buildings go the same way, layering technologies and crossing the border between old and new materials?
Doing this will require more interaction between experts from different industries, and I would like to see more of it. The construction sector is not very diverse in its approach, and I think we have a problem with asylum mentality in general, but real innovators will cross the boundaries between disciplines.

Textiles, for example, are fascinating for architects because they can do things that normal construction materials cannot do. You can see this with the lightweight pneumatic panels that cover many stadiums. Temporary structures are another sector that could benefit from innovative textiles. Millions of refugees need decent housing. Smart constructions made with resistant and lightweight fabric could be quickly sent, packed and reused.

In the future, building materials will be more diverse because people themselves are so diverse with their needs and desires, and constructions will reflect that.

 

You suggested replacing school libraries with workshops where students could get in contact with materials. Does a digital generation really need the physical experience of touching and feeling stuff?
I think the digital world is just one aspect of life. It clearly isn’t the answer to everything. Humans are physical beings; they need food, sleep and shelter from the weather. My radical proposal came after seeing the massive decrease in the facilities for learning with materials. For some schools, digital technology has been an excuse to reduce the resources for physical workshops because they are more expensive.

Whenever we introduce students to physical stuff they love it. And if we combine their digital skills with material knowledge, we can actually empower them. Professionals, too, need to cope with the wealth of new stuff. The number of materials from which designers can choose has almost quadrupled in the last 15 years.

This is why we are now seeing more materials libraries: facilities that collect samples so that designers and engineers can find out how materials could be used.

 

What would be your dream material for a building?
I’ve always fancied buildings that harvest their own energy. On a more immediate scale, I would like constructions to be thermochromic, meaning that they would change their colour with temperature.

Buildings could turn white in summer reflecting more sunlight, and thus reducing the need for cooling. And they could become darker in winter to absorb more heat and thus save energy.

Thermochromic glasses are already on the market. My laboratory developed a thermochromic brick about 10 years ago. We couldn’t get any company interested, but we showed that such a brick was possible.

This material makes total sense from an environmental perspective. As an extra, I would love to be in a city where the buildings change with the seasons.

 

By Sergio Pistoi

21 April 2016