Double glazing, particularly the film-coated k glass and argon-filled variety, is fine for the winter season. But in the summer, buildings so equipped can become excessively warm.

BorgCo address this challenge with a new range of fluid-fillable triple glazed units.

The inner pair of panes form a standard argon- filled glazing unit.

The space between the middle and outer panes has two pipes, one in the base and the other at the top.

In the summer, this gap can be filled from a concealed reservoir on demand with a neutral density fluid- for cheapness, probably deionised water plus pigment and detergents. The liquid is pumped through the outer panel by thermo- syphon, assisted by a small pump.

Depending on the mix, the liquid absorbs both visible light (dimming the room) and infra-red (preventing excessive heating).

The liquid is circulated to an external dissipator, or can be used to provide useful amounts of hot water through a heat exchanger.

When the liquid is no longer required, it is allowed to drain back into the reservoir; the surfactants and controlled draining prevent droplets being left on the glass.

An option for rinsing with DI water may be developed.

After draining and rinsing, warm dry air from a dessicator is blown through the panel to remove moisture and prevent condensation.
-- 8th of 7, Sep 22 2013

A good idea as long as they clean up without misting or staining. The other issue would be the ramification of homeowners who are a bit tardy draining them before the first big frost. [+] though.
-- AusCan531, Sep 22 2013


If you didn't mind custom pressing your glass for every latitude (and orientation in the most effective version), it would be fairly easy to make windows that admitted essentially all light in the winter and much reduced light in the summer.

The simple version just has triangular prisms with one side opaqued, such that if the sun is above a certain angle, much of the light is blocked. The more complex version corrects for orientation, so the sun is blocked for much of the day.

As far as selectively blocking infra-red, Low-E windows already do this. It's been determined that it's generally worth blocking the IR in the winter because the output from a heated house is greater than the input from the sun.
-- MechE, Sep 23 2013


[MechE], unless the sun IS your winter heat source. A well designed house should hardly need any extra heating if the sun is shining.
(At a recent housing expo here, a vendors house was 20degC inside, -5degC and snow on the ground outside. With NO internal heat source at all.)
-- neutrinos_shadow, Sep 23 2013


// tardy tardy draining them before the first big frost. //

Glycol in the fluid.

The prism idea is nice but it only reflects; no energy collection. A good passive solution, though.
-- 8th of 7, Sep 23 2013


Most passive solar designs accomplish the same effect by using awnings or similar designs to shade the window from high angle sun, but allow low angle sun. For the highest efficiency, you use retractable awnings.

Passive solar designs, however, are still rare because they do, to a large extent, require that the house be built deliberately with that in mind, and require the house to be oriented in a way that cannot often be achieved except in rural construction.
-- MechE, Sep 23 2013


// in the summer, buildings so equipped can become excessively warm. //

Here in the barbarian wilds we have windows that open and let in fresh air. Then again, I'm not sure why I expect the English to be familiar with the concept of 'fresh air'.
-- Alterother, Sep 23 2013


In conceptual terms, "summer" is often more of a problem ...
-- 8th of 7, Sep 23 2013


It's the time of year when the entire West Country smells of fart and tall pale middle-aged Englishmen expose their pimpled buttocks on the shingle at Torquay.
-- Alterother, Sep 23 2013



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