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Should I replace my double-glazed windows with triple-glazed ones on the north side of my West Seattle home?

Should I replace my double-glazed windows with triple-glazed ones on the north side of my West Seattle home?
Should I replace my double-glazed windows with triple-glazed ones on the north side of my West Seattle home?
By BettyLoucal Sep 13, 2017


Many people – well, some people, at least – have a different level of glazing on different sides of their house. In the Puget Sound, we have a few challenges. The winters are long, dark and wet. It never gets to be cold like in the Midwest or other such places, but unremitting dampness presents unique challenges to a window frame. We also get relatively little sunlight, again when compared to many other parts of the country. That’s because we are both further north, and have a lot more cloud cover than most parts of the country. While Florida, for example, gets more precipitation than we do, they get more hours of sunlight. The ultraviolet light from the sun effectively bleaches mold or other types of fungus right off your window frames. That’s in Florida, anyway. Here is the Pacific Northwest, however, one side of your house may never actually see sunlight. Given the right angle and a few evergreens, a north facing side of a home may never actually come in contact with the cleansing effects of the sun’s ultraviolet light. That means, that side of the house may be harder to heat and harder to keep warm.

Triple glazed windows offer more heat insulation

Triple glazing is an attractive option. Triple glazed windows are only slightly more expensive to buy – over the price of double glazed windows, all else being equal – but they don’t offer that much extra heat insulation. Still, such triple glazing offers other excellent benefits, above and beyond simply lowering your utility bill slightly.

The sound insulation benefits of triple glazed windows

It’s not immediately obvious, but a modern window, including the glass panes, hinges, frames, latches and locks are possibly the most sophisticated part of your house. That’s because they have to provide structure and support for the house, and yet have moving parts which must fit perfectly together even after years of use, and still let light in and provide some security. No other part of the house that I can think of must perform so many functions. OK, I hear you say “washing machine”, but that’s not actually part of the house.

I remember one evening when I came home to a house I was then living in, the whole front of the house had just gotten a complete set of triple glazed windows. It certainly looked like a professional installation project but what struck me more than anything was the complete silence when the windows were closed. I could hear my heart pushing the blood through my ears, it was so quiet! I didn’t realize just how much ambient street noise was leaking into the house from outside. Now, the old window frames themselves had needed to be replaced, but it was still extraordinary. I recommend you visit a building that has triple glazing to experience this. And in the Puget Sound, it is only going to get worse, it seems, as population density increases and noise levels go up with that.

A new kind of privacy with triple glazed windows

Did you ever look at a newly constructed building and say to yourself, that glass looks rather green? Well, most average glass production produces a green tint. I’m guessing it’s something to do with the common elements of glass production, but it has another effect: it makes it harder to see inside from the outside. With monitoring cameras becoming more and more ubiquitous these days, a little more privacy might be nice, too. As light goes through glass, the thicker that glass is, the less light will make it to the other side. No glass is perfectly transparent – you probably know that only diamonds are close to transparent – but there is another factor at play with respect to transparency. Three panes of say ¼ inch thickness each actually blocks out more light than one pane of ¾ inch thickness. It’s because, as the light leaves each pane, enters the next pane, and so on – three times – each time it loses a little bit of its power. Some light – as well as its UV constituent – gets bounced back from each of the three surfaces, therefore having a greater insulation effect than a single, thick pane of glass.

Heat insulation properties of triple glazed window installations

Back to the topic of heat insulation. In the Pacific Northwest, we are less interested in preserving the benefits of air conditioning (although if this 2017 were any indication of future hot summers, that might change) and more interested in keeping the costly warmth inside the house during the colder seasons. In between the individual panes of glass in a double or triple glazed window is a particular type of gas that is less heat conductive that just plain air. During the manufacturing process, the gaps between the panes are filled with a special mixture of gas, and the unit is hermetically sealed at that point. That gas makes it tougher for Mother Nature to suck the heat out of your house, and it therefore saves you money. Aside from doors – of which you only have two or three perhaps in a single home – the typical home’s windows are the biggest heat loss gateway of most houses. And if you have, for example, twenty windows in your home, each one of those is an opportunity to watch the dollar bills fly out between the cracks and imperfections.

Triple glazing – really, the two gaps between the panes – are very effective insulators. If you remember from your childhood, you might have had single pane windows – I know my parents did – and the entire window would freeze solid. I remember one winter, a cold spell got so bad, the inside of our windows were covered in an ever thickening later of frozen condensation. The glass got so cold, it grabbed all the moisture out of the interior air and it froze solid. You could see just exactly where the insulation was not working. The heavy, cinder block walls seemed to keep some heat in, but the single thin layer if glass was just a little bit better than having a gaping hole and no glass whatsoever. Anyway, triple glazing creates a superb barrier to heat loss. The interior pane of the three stays close to room temperature, and conducts almost no heat at all to even the next pane. And the third, exterior pane is that additional barrier.

Triple glazing is the way to go. If you can afford the slightly higher cost.

Image by Daniel von Appen

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