Not everything is as it seems. The glass that was clear is suddenly opaque, sunlight is turning into electricity and the paint on the walls is absorbing a bad smell. I’m not venturing into the wizard world of Harry Potter but the very real realm of smart materials. Unlike most everyday materials, which have physical properties which cannot be significantly altered, smart materials have one or more properties that can be dramatically altered.

Smart materials respond to stimuli like light, temperature or magnetism by changing their form, volume, colour, viscosity or conductivity. For example, a fluid which flows easily might turn into a solid.

In buildings, smart materials have real benefits when it comes to comfort and energy. What we sometimes don’t realise is that we’re using them already. The photovoltaic panels that we’re putting up on our roofs incorporate smart materials in the arrays of cells that convert sunlight into electricity. When sunlight strikes them, photons of absorbed sunlight dislodge electrons from the cell’s atoms. Free electrons then flow through the cell, generating energy.

One of the smart materials that caught my eye a few years ago is Energain, a ‘phase change’ material composed of a high-tech compound containing microscopically small droplets of wax. Phase change materials are used to stabilise temperatures inside buildings to prevent overheating during the hottest parts of the day. They work due to the physical phenomena that occurs when the wax changes from a solid to a liquid state. When this happens a large amount of thermal energy (known as latent heat) is consumed from the environment without the temperature of the material itself changing. At night, when temperatures fall again, the wax re-solidifies and releases warmth back into the room. This cuts the need for air-conditioning, saving money and energy.

Keeping heat out of buildings by controlling sunlight is equally important when it comes to conserving energy. This is exactly what SPD SmartGlass does. Infinitely variable from clear to dark, the glass incorporates ‘rod shaped suspended particle molecules’. The orientation of these can be ‘tuned’ precisely using electricity to regulate the amount of sunlight, glare and heat passing through the glass.

 

Long described as an impossible dream, self-cleaning glass is another product that is now a reality. The secret of Pilkington Activ is its special coating which reacts with the ultra-violet rays from daylight to break down dirt which is then washed away by rainwater. This has clear environmental benefits because the glass doesn’t need cleaning so often and milder cleaning products can be used. 

So what about the horrors of a Hogwarts stink bomb? StoClimasan Color is a paint based on the natural principle of photosynthesis - converting light energy into chemical energy - to attack odours and airborne pollutants caused by organic compounds. It’s much like a white blood cell attacking a germ and the organic compounds are broken down into trace amounts of their constituent parts, water and carbon-dioxide. That’s smart, maybe it’s even magic.

Images: StoClimasan Colour / Energain, DuPont

This post was written by Roger Hunt at http://huntwriter.com/