High performance windows installed

Windows are one of the most critical elements of a Passivhaus and any super-insulated energy home. The placement of the windows, the type of glazing, the type of coating, and the frames all have an integral role in how much or how little energy your home will use. But what most energy aficionados consider to be the most important is the frame. For us, the only real option was fiberglass. Most regular home install run of the mill vinyl, wood or metal – but these materials are simply highly inferior to fiberglass when it comes to energy performance.

“Fiberglass is created by pulling strands of glass through a heated die, resulting in a material that is strong, resilient, and suited to all weather conditions… Energy efficient frames have low conductivity that discourages the transfer of heat or cold into a building. Fiberglass has a much lower conductivity than metal options; simply placing a hand on a fiberglass frame compared to an aluminum frame in -20°C weather makes the difference very clear… Fiberglass is much less conducive to allowing cold temperatures to pass through the frame, thus helping to prevent condensation and loss of heat… Subjected to temperature extremes, windows must remain stable, with minimal expansion and contraction to keep an excellent seal. Considering that the bulk of a window is glass, what better material to surround it with than glass? Hence “Glass on Glass Advantage”. Composed of about 60% glass, fiberglass, like plate glass, has a very low rate of expansion and contraction. Fiberglass maintains an excellent seal with reduced movement relative to the plate glass. Superior stability also results in greater longevity, fewer seal failures, and better paint adhesion.” -Duxton windows

Although we are targeting Passivhaus performance levels for our house, actually purchasing “Passivhaus Certified” windows was simply far too cost prohibitive (~$90/sq.ft.) and must be shipped across the ocean from Germany (that is a big carbon footprint to overcome). There is one Passivhaus manufacturer of windows in Canada that I’m aware of called Northwin, but we didn’t pursue a quote from them, the only reason being is that no one around here had any experience with them, and from what I was told the cost was extreme. I had wanted a recommendation or at least a review from someone who had worked with, lived with or installed them before.

One of our friends had built a very energy efficient house and installed Fibertec windows out of Ontario. Although they were beautiful looking windows, they had nothing but problems with them (air leaking, condensation). My thought is that these windows, made in a warmer part of the country, were not designed with a cold prairie climate in mind (I have no evidence to prove this, mind you). As such we avoided any manufacturers outside of our climate zone. That basically let us with two fiberglass window manufacturers: Duxton windows and Accurate Dorwin, both from Winnipeg MB.

We knew people who’d either installed or worked with these windows before and each of them were happy with them. We received quotes from each of them and they were essentially equal (Duxton being $500 more). We ran the two windows through the energy modelling software and Duxton came out the winner. I’d also talked to a Passivhaus engineer who’d found that Duxton “performed very well in the PHPP.” My wife also liked the name “Duxton” better.

They are a pretty impressive and innovative company. We actually met the owner, Al Dueck, and had a drink with him at a Building Green conference a few weeks ago. The company has recently developed a quintuple paned window! Five panes with a rating of R20! Outrageous.

We ordered the windows way back in early May, before the ground had even been broke on the foundation. I’d been expecting this to be more than an ample amount of time for them to be fabricated and delivered. Well, I was wrong. So very wrong. Although I was told that they would be ready in 6 weeks, they weren’t actually delivered and installed for nearly 10 weeks. Fortunately for us, our builder and the subcontractors were willing to continue on and not wait.

We had everything coordinated when they confirmed at last that the windows and doors had been sent out. Our builder, received the shipment, unloaded them and said “WTF!” We were missing all of the doors and one of the largest windows. It was the end of the day and we scrambled to try and find out which of the three shipping companies may have lost them… but all of them confirmed, when I called them frantically, that they had received the same items. It wasn’t until the next day that we received a sheepish email from Duxton that they had “forgotten” to ship them. Oops!? What a headache.

Not only were we trying to coordinate the shipping, delivery, installation of the frames and smaller windows, but also the “site glazing” (6 of the windows were too large and heavy to be sent as a single piece, therefore the glass and frame were sent separately and had to be installed by another subcontractors). Basically there was a lot of pieces that had to fall into place. And none of them did. But after hours on the phone rescheduling everything, like most (kind of) things, in the end it worked out. The windows and doors arrived and were installed. And they look super sexy.

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Frames only. Waiting for site glazing.
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The triple pane pieces of glass. These made me so nervous. I did not want to be around when they were installed.
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Almost all installed. Note – no door and no window on the far end.

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High Performance Windows

One of the things I am most excited about in our house are the windows. We have a lot of windows in the house, 25 to be exact. And they are not terribly small. Even before knowing anything about energy efficient building, I’d always loved homes with large expansive windows overlooking a beautiful view. However, when building an extremely energy efficient home, the placement, size, glazing, window to floor ratio, and type of window matter a lot.

First, and perhaps most important, is which direction your windows should face. Obviously in the northern hemisphere, the sun is in the south. Therefore, the majority of your windows should face south and be able to take in the sunlight through the winter months when the sun is lower in the sky to provide some passive heating. Conveniently the sun is higher in the sky in the summer, so as long as you have properly sized overhangs or shading in the summer then you can prevent overheating. Recently we were in a neighbour’s house that was not designed with energy efficiency in mind. They have large south windows that are completely exposed, as well as some larger east and west facing. Even though they would (theoretically) have a great view, they had the interior blinds drawn on almost all of the windows!  Interior blinds and shades do very little to prevent overheating as the light/heat has already entered the space and will simply heat the blinds and radiate inside anyway.

For us, we maximized our southern exposure (but not too much as you can still overheat in the winter – even at minus 40° Celsius). And minimized our northern, eastern and western windows. Fortunately for us our best view is to the south and east. We do have a couple large windows on the east side of the house to take advantage of the river valley and our unobstructed view of the sunrise (to not put windows there would be foolish). We would have liked to have put more windows on the east, but in order to do so that would require shutters on the exterior, thus obstructing the view anyway. Shutters are really the only way to “shade” light from the east and west as the sun is too low in the sky throughout the year (at sunrise and sunset) to actually “shade” it. As for the north we don’t have much of a view, and so only have two windows. One in a bedroom for ventilation and fire safety and the other in the hall for ventilation. Northern windows really don’t provide any benefit in energy efficiency and are actually an energy penalty.

As for glazings, these are really amazing and can help with heat gain or blocking unwanted heat.The glazing does not at all block the view. I think of it like sunscreen. On the east and west windows, you want more sunscreen because you don’t want to overheat. On the south you want minimal sunscreen because you want that good passive heating in the winter (as long as you account for passive shading in the summer).

Ok so what type of windows do you buy? Wood, PVC or fiberglass? We had really hoped that we would be able to afford fiberglass windows. These are simply the best for energy efficiency, durability and quality. The frames themselves are made of 60% glass (fiber-glass) and so they move with the expansion and contraction from the heat and cold of the windows. Consider -40°Celsius outside and +20°Celsius inside. That is a 60° change that occurs through about a one inch space. PVC and wood will flex and bend at a different rate then the glass, leading to more air leakage, reduced air seal, and eventual failure of the window over time. Fiberglass however does not have the same issues. Duxton Windows has some excellent information on their website.

Duxton fiberglass windows

Now that we had an idea of what we wanted, we needed to determine which supplier to go with. We priced out Duxton (fiberglass), Accurate Dorwin (fiberglass) and Plygem (PVC/wood). We did not consider any of the crazy German imported windows. Shockingly, people actually do this (this is where the economics of Passive House and extreme energy efficiency clash with reality and sustainability, as I’ve written about before). I was actually talking to a house designer the other day who was raving about some German windows they’d started to import. Indeed they are impressive windows – but they are coming from fricking Germany! My thought when building a “sustainable” home is that we should be really considering if we are spending our money wisely or if it could have a better effect elsewhere (for example, spending $15,000 more on windows to get a marginal energy improvement versus $15,000 in solar panels). AND if you are importing your high performance windows from 4000 miles away and shipping them on a cargo ship across the ocean… well… is that sustainable?!

Anyways, I knew that the fiberglass windows would be more expensive than wood/PVC – but how much more was the question? When we received the quotes back I was pleased to see that the fiberglass windows came in only 20% more expensive then PVC. For the added efficiency, durability, warranty and, not to mention the larger viewing area of the window (fiberglass is stronger therefore can have a smaller frame and more glass) it was a no-brainer to go with fiberglass. We ended up choosing Duxton over Accurate Dorwin due simply to the fact that our designer had recommended them. The price difference between the two companies was marginal.

Via duxtonwindows.com

In designing the house and choosing the windows I tend to think about what Christopher Alexander of the Pattern Language says: “light on two sides of every room.” I loved reading this book because it was all about aesthetics. Written in the 1960s, it did not give a crap about energy efficiency. It was a nice reality check against all of the energy efficient dogma that in some cases can really get out of control. You still need a home that you actually want to spend time in.

Pattern Language by Christopher Alexander