Gas-Filled Glass

You see it advertised in window commercials: low e and argon. But what is this stuff that makes normal windows better?

By pure physics windows are not good insulators. In other words heat slips through windows as if they were made of metal and not glass. Now, if the frames are metal the whole unit is an energy-draining portal. By changing to a vinyl frame with a closed-cell foam filling the R-value goes up dramatically. It is withing the glass that the majority of heat loss takes place.

Heat travels by radiation, conduction and convection. The sun’s heat comes in through radiation and heat loss comes from conduction as the glass draws it outside to the cold. The other heat drain is convection which speed up the conduction process in the air space within the glass panes. By slowing down this process the heat loss drops.

By filling the space between the glass panes in a window with a heavy gas the convection slows down. This means that the circulation from hot to cold within the sealed glass is stalled by the weight of the gas. Argon is such a heavy gas and krypton is even heavier. They slow to a crawl the natural air movement which keep the heat from surface of the interior pane, which is room temperature, from transferring to the outer pane, which is the temperature of the outside air.

So, from an R-value of barely 1.5, the argon gas-filled panes, with low emissivity coating to reflect heat back into the home, can get as high as 4, which is a huge savings in the glass business. With 3 panes this goes up even further.

Greenhouse Building

For a great article on greenhouses go to Greenhouses