What is a Nanoparticle? 

A nanoparticle is a small object that behaves as a whole unit in terms of its transport and properties. Small might actually be an understatement, these guys are only between 1 and 100 nanometres (nm) in size with a surrounding interfacial layer. You might believe that no one has heard of them outside of a modern day science lab but Nanoparticles were actually used by artisans  in the fourth century Roman Empire as seen in the famous Lycurgus cup made of dichroic glass. We also find these little guys in ninth century Mesopotamia  used to create a glittering effect on the surface of pots. In modern times, pottery from the Middle Ages and Renaissance often retains a distinct gold- or copper-colored metallic glitter. 

We know…this sounds like a lot of science garb and not at all applicable to replacement windows & doors…right? Wrong! Consumers in 2018 are more concerned with energy efficiency and conservation than ever before, a trend that we expect to continue to rise in 2019 and beyond. In an age where you can purchase a “smart” anything the building materials industry, especially window and door manufacturers have been on a mission to produce smarter windows, that are more energy efficient than anything we have seen before and it seems as though these products may not be to far away.

R & D Magazine reports that researchers from the U.S. Department of Energy’s Argonne National Laboratory have developed a new process to synthesize vanadium dioxide nanoparticles that could yield more economical, energy-efficient, and thus smarter windows. The magazine states “In thermochromic smart windows, infrared energy is passed to keep buildings warm in the winter and blocked in the summer to keep them cooler. The material is able to rapidly switch and transition from blocking infrared light to passing it. The nanoparticle-based vanadium dioxide films have about twice the solar modulation values for high and low temperatures as the thin films currently being used for smart windows.”

Over the years there have been a number of “smart” electrochromatic window designs but these have all mostly aimed at changing tint or opacity. On the contrary the nanoparticle smarter window design uses a fluid suspension of iron particles. This fluid is contained within the window in a series of long vertical channels. These “functional fluids” allow the window to change opacity  while also absorbing and distributing heat. The iron-infused fluid remains diffused until you switch the window on — the nanoparticles cloud up the channels and block light. When you flip the switch, magnets drag the nanoparticles out of the liquid to make the window fully transparent. When the magnet is switched off, the nanoparticles are resuspended to darken the panel. In general, the more nanoparticles you add, the darker the window becomes. You can even completely black it out with enough iron and we are definitely here for that! 

The end goal is to cut back on energy costs, particularly in terms of heating and cooling of buildings which can make up a huge percentage of energy consumption. The design has already been funded to the tune of several million euros, and commercial applications are apparently planned for later this year. Our future selves might look back and wonder how we ever handled having just plain old glass in our windows.