A quadruple pane window from Serious installed in a hempcrete wall in the Nauhaus Prototype
Well, we finally got the windows and doors installed. Okay, let me vent for a sec: prototypes are a bitch. We had to do a lot of head scratching and trial and error to figure out the best way to insure airtightness in our installation. The hempcrete is awesome, but it create its own set of challenges, especially since our truly wonderful Serious windows aren’t really designed to be installed in the middle of thick walls. (Serious is a partner with us on this project and we’re working with them to make things easier when you decide to replicate what we’re doing.)
First, let’s sing the praises of these windows. Though a number of German companies make windows in this category, Serious Materials is the only US company that can meet the required specs for a Passive House. All window and door units on the project have fiberglass frames and quadruple pane glazing. Southern glazing has a center of glass insulation value of R-7 with an impressive solar heat gain coefficient (the percentage of solar heat that passes through the glass, 1.0 would be 100%) of about 0.7. This allows for heat gain from the low southern winter sun, a strategy integral to the Passive House integrated design system.
North, east, and west glazings weigh in at an amazing center of glass rating of R-11, a rating equal to the fiberglass insulation in some conventional stick frame walls! This is compared to R-2 for a typical double pane window found on most US projects. Unlike the heavier European windows, Serious reaches this performance level with two pieces of glass and two pieces of plastic allowing for a thinner profile more like conventional windows typically available in the US.
Why all the fuss? Well, I’ll tell you. In a Passive House in our climate region, walls need to be about R-40. Sticking an R-2 hole in an R-40 wall just doesn’t make sense. In a Passive House, the idea is to spend money on passive elements, extra insulation and really good windows for example, that don’t require energy inputs to do their job once installed, unlike heating, cooling, and ventilation equipment. In the right configuration, these passive elements combine to allow for a much simpler and less expensive mechanical system, thus saving money in construction and afterwards with much lower energy bills.
Anyway, we’ve got video footage that we’ll eventually compile into a bunch of great educational how-to videos on the ins and outs of all this nifty construction detailing. If anyone out there is getting antsy for the goods, getting us a grant to fund collation of the documentation footage would really speed things up. Until then, wet your chops on these few photos:
Here you see our custom plastic lumber sill piece with groove for backer rod and space for spray foam, the edge of the bituthane sill pan (green stuff), and the poured in place concrete exterior sill.
All windows had to be pre-drilled through the fiberglass frames...
...then screwed to the stud framing in the middle of the hempcrete wall.
Jeff puts his engineering degree to work installing a backer rod as part of a multi-step installation process to insure maximum airtightness
The plastic lumber sills were filled with foam after installation through a series of pre-drilled holes...ingenious!
Southwest view showing windows installed. Doesn't look like any big deal, does it?
Master carpenter and benevolent genius Tim working on a door. Installing the doors was a whole different story...don't get me started!
This is one of the very few articles that addresses mean radiant temperature. In many cases the energy lost out the window through conduction is less than that wasted in order to overcome the comfort effects of cold windows. For example, last winter we installed a Window Quilt in a very small college dorm room with one fairly large north facing window. The occupants stopped using their 1,500 watt supplemental heater and were finally comfortable in the room. Note that none of this energy saving is captured by the typical energy auditors’ calculation. For a more detailed explanation see the video at http://www.windowquilt.com.
Larry,
We have done a lot of research on movable insulation and have gone back and forth about its effectiveness. For new construction, glazing options have become so energy efficient it’s become a rational question as to whether it’s cheaper and more effective to put the movable insulation money into better glazing. Of course, for upgrading an existing leaky windowed building, I’m sure the argument is more clear cut. However, our analysis is hampered because we have never been able to find any actual test data for window quilts like those you sell. Is there test data to back up the specs page on your website? If so, we’d love to see it.
Thanks,
Clarke
Hi,
Hope to build with Faswall block and Serious windows this summer and will be revisiting the site to see how things worked out with your install.
Dave
Whitefish, MT