Siberia Overheating With Double Glazing

Can double glazing cause overheating in Summer?An OVER-Heating Lesson For Double Glazing- From Siberia!

I’m a longtime fan of Melbourne Environmental Consultant, Alan Pears. Alan is an Associate Professor at RMIT, and described by Wikipedia as “a pioneer of energy efficiency policy in Australia since the late 1970s”. I’ve met Alan, and I’ve corresponded with him on the subject of heat pump hot water systems.

As I’m very interested in the fields of energy efficiency, renewable, and particularly double glazing, I was fascinated to see a new article from him in Renew Economy, on his recent experience in Siberia. Believe it or not, during the short Summer season, some new Siberian residences are overheating. That’s right- OVER heating.

It seems that modern, well-built and designed units there are being built with excellent insulation, including double glazed windows. Unfortunately, they are also often being built without any shading of the windows. Great during Winter, but like an oven in Summer.

It’s an extreme lesson from Siberia, but it brings home a point for our local, Australian market. While double glazing does wonders for letting in sunlight and keeping in warmth during Winter, we need to plan for proper shading of windows that are sunlit, to prevent overheating in Summer.

Shading can be from properly-sized eaves on our houses. If that is insufficient to keep out the Summer sun, then we need to look at alternatives. These could include;

  • awnings over the windows
  • shadecloth protecting the windows
  • shutters on the windows
  • inbuilt venetian blinds for the windows

Double glazing is a brilliant product, which provides a whole raft of benefits. We just need to make sure we don’t sabotage their ability to do a wonderful job for us.

You can read Alan’s article here

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Tunable Smart Windows

Smart window development at Harvard University.

Say Goodbye To Blinds? Harvard Smart Window Development

Affordable, effective smart windows may be some time away, but new research at Harvard University has the potential to be a game-changer. The Harvard Press Release describes it like this…

Researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences have developed a technique that can quickly change the opacity of a window, turning it cloudy, clear or somewhere in between with the flick of a switch.

Tunable windows aren’t new but most previous technologies have relied on electrochemical reactions achieved through expensive manufacturing.  This technology, developed by David Clarke, the Extended Tarr Family Professor of Materials, and postdoctoral fellow Samuel Shian, uses geometry to adjust the transparency of a window.

The research is described in journal Optics Letters.

The tunable window is comprised of a sheet of glass or plastic, sandwiched between transparent, soft elastomers sprayed with a coating of silver nanowires, too small to scatter light on their own.  

But apply an electric voltage and things change quickly.

With an applied voltage, the nanowires on either side of the glass are energized to move toward each other, squeezing and deforming the soft elastomer. Because the nanowires are distributed unevenly across the surface, the elastomer deforms unevenly. The resulting uneven roughness causes light to scatter, turning the glass opaque.

The change happens in less than a second.

It’s like a frozen pond, said Shian.

“If the frozen pond is smooth, you can see through the ice. But if the ice is heavily scratched, you can’t see through,” said Shian. 

Clarke and Shian found that the roughness of the elastomer surface depended on the voltage, so if you wanted a window that is only light clouded, you would apply less voltage than if you wanted a totally opaque window.

“Because this is a physical phenomenon rather than based on a chemical reaction, it is a simpler and potentially cheaper way to achieve commercial tunable windows,” said Clarke.

Current chemical-based controllable windows use vacuum deposition to coat the glass, a process that deposits layers of a material molecule by molecule. It’s expensive and painstaking. In Clarke and Shian’s method, the nanowire layer can be sprayed or peeled onto the elastomer, making the technology scalable for larger architectural projects.

Next the team is working on incorporating thinner elastomers, which would require lower voltages, more suited for standard electronical supplies.

Harvard’s Office of Technology Development has filed a patent application on the technology and is engaging with potential licensees in the glass manufacturing industry.

It’s usually a long, long way from a research Press Release to the commercial availability  and viability for a product such as smart glass, but this is perhaps a window on and of the future.

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