in pursuit of energy efficient minimalism
The weekend before Christmas, we received an email from Andrew Kline to meet up for coffee. Andrew is president of Green Generation Building and not only built and developed the first Passivhaus in Ohio (Yellow Springs), but is apparently the youngest PH builder in North America to date. We thought it would be a good way to share information, and after talking shop for an hour or so, the conversation led to an interesting topic – what in the world are the options for Passivhaus doors in North America?
We’ve covered European Passivhaus windows a little, the Teslas of the fenestration world – especially when it comes to quality, airtight wood windows. And when it comes to doors, it’s pretty much the same story. While importing European PH windows can save carbon, we’re not so convinced it is necessary for doors – however, if importing windows is already planned it might not be that much to toss in a certified Passivhaus door. Especially when compared to having a local company take a stab at custom fabricating one.
First off, a little info about Passivhaus doors…
Passivhaus Institut recommends doors have a U-value (SI) of 0,8 W/m²k (R-7.1). They need to have a multi-point locking system (this sucks the door into the frame, providing a tighter seal) and should have multiple seals for maximum airtightness. They should also be durable, and look sh*t hot. Ok, that last one’s not a necessity per se, but it certainly helps. Doors are also a little trickier than windows, especially when it comes to detailing, due to threshold requirements. Unlike windows, the entirety of the door frame can’t be overinsulated and thus may have a higher thermal bridging coefficient.
We prefer doors to do double or triple duty – this means thinking of them as windows (and entering as such in PHPP) and maximizing glazing for solar gain. This has the added benefit of making them a little more modern. Like Passivhaus windows – door glazing and spacers should also be high performance. In training, Katrin mentioned thermally broken locks would be a wise investment, otherwise you may have condensation and freezing issues. Obviously not really a problem here in Seattle, although the last week of frosty weather leaves us thinking we should move to San Diego…. And yes, even the threshold should be thermally broken.
So what to do when sourcing a Passivhaus door… As far as we can tell, there are basically four options:
1. install an ‘energy efficient’ North American door
2. import PH doors (Europe… China?)
3. hack your own
4. custom job
North American Options
Options for North American Passivhaustüren are definitely limited. For the most part, it seems this is an affordable and/or ‘take the hit for poor performance/mediocre design’ approach. A few projects have utilized Therma-tru and Innotech doors. We’ve also seen discussions on PH blogs about using Pella stock doors. Both Tad Everhart and Blake Bilyeu utilized Innotech for the entry doors on their Passivhaus projects in Oregon. According to the Passivhausdatenbank, Katrin Klingenberg’s home in Urbana utilized a foam-filled fiberglass door by Thermotech.
While there are local solutions that could suffice, it seems that a number of passivhäuser in North America have opted to import doors. This option is definitely not cheap (US$2,000-6,000 per door, plus shipping) it definitely presents an opportunity to obtain high-quality, high-performance doors. A number of PH projects spec’ing Optiwin windows have used the Frostkorken door, which matches the window system. Importing doors and windows comes with longer lead times and warranty/replacement/service issues that may be hard to deal with if problems arise.
Optiwin’s Frostkorken door has been utilized on the BioHaus in Bemidji, as well as the recently certified Passivhaus in the Woods.
Our friends at Root Design Build opted to go with Internorm’s insulated aluminum-clad wood door to match their windows. Due to the weight, the door and adjacent relite had to be shipped as separate units and assembled on site. Their blog has more information and photos on the installation of this stunning door.
Hack your own
There are numerous blogs/websites on how to take cheap products and hack them to make them better - ikeahacker being a personal fave. Perhaps the most cost effective method would be to take a stock entry door from Lowe’s or Home Depot (with a good U-value!) and cobble together a few hacks to make it airtight. It may even be possible to cut an opening and install a triple pane IGU, if this approach seems justifiable. If aiming for a door with design integral to the windows, this approach probably doesn’t make sense. But if merely trying to pass the blower door test, it may prove most economical. We haven’t heard or seen of this yet, but if anyone has attempted this, we’d be interested in knowing how it worked out.
We’re definitely a little more interested in this method, getting our hands dirty and designing/fabricating our own doors. While the imported doors tend to look fairly stunning and perform beyond almost anything you can find here, they’re definitely not what we’d consider ‘affordable’. In fact, you should be able to study a few key details from a system and develop a PH or near-PH performing door. A good woodshop or craftsman should be able to get an airtight frame (if properly detailed…) and as long as the glazing and spacer are properly spec’d and installed, may allow for a phenomenal custom, high performance door. Hardware seems to be fairly common for PH doors – G.U., Hoppe… The hardest part is ensuring the door frame is properly insulated and thermally broken.
This was the approach Andrew undertook for his Yellow Springs house, using polyurethane for the door’s core. This makes sense, although a better method might utilize vacupor (vacuum insulation), which at up to R-30 per inch, could mean a thinner, lighter door.
Better yet… Once you’ve developed a bulletproof door that not only performs well, but looks great – sell it to other passivhaus consultants! We at BFC have tossed this idea around a few times, especially as the options for wood doors are somewhat horrendous here in North America.
The Bagley Nature Center classroom in Duluth (PHBdW 11) utilized a custom solid wood door with insulated core by WoodMax. The door is minimal, not offensive and blends in well with the facade.
Doors can definitely be a weak point when it comes to achieving the Passivhaus standard, especially due to airtightness. Patio doors are highly vulnerable – we sat in on a blower door test last year where the largest source of air leakage was through the area around the astragal of a patio door. Another option for patio doors is lift-slides, which allow for a more airtight seal than sliding doors.
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