Sunday, January 18, 2015

CoA visitors look at energy efficiency, up close and personal

Picture: Our old farmhouse gets new insulation and siding, a few summers ago.

Friday started out warm but turned very cold and windy in the afternoon. Despite this, we received a small group of four student visitors, including their TA Nicholas Urban, all from College of the Atlantic, who arrived in the midst of an Arctic front which manifested itself in the form of a small blizzard.
This rather dramatic entrance notwithstanding, this also happened to be the day before the same group of students appeared in a New York Times feature about their renewable energy studies, a coincidence that seems remarkable enough to post about on the blog, and a reminder of how topical our work has become. Here's the article, plus an earlier one from Revkin's blog.

We began our visit on campus, where Admissions Ambassador Gunnar gave them a tour of the Terra Haus, our (almost) net zero passive solar dorm building. Gunnar is one of the residents of this award-winning building. 

We were then supposed to have Q & A with me about renewable energy and energy efficiency topics, but our small baby Roo, with whose welfare I was entrusted that day, wasn't having any of it, so I had the students drive by our farm on their way home, in hopes of getting Roo "down" or at least quiet so we could continue the conversation without the cries of a baby interrupting things. This ploy succeeded, somewhat to my surprise. 

The result was additionally fortuitous because, unbeknownst to me at the time, their main topic of interest was Maine home energy retrofit. I had assumed they wanted to talk about finance, a topic that was mentioned in the emails we exchanged. But our old farmhouse has been extensively retrofitted, and so we were able to take a tour and explain how it all got done and what was generalizable from that. The students are planning a business in energy audits. I'm not sure whether they will actually start the business or not, or whether this is primarily a class exercise. 
Either way, they got some good information.

One main concern I was careful to highlight is that you really can't just audit and retrofit old Maine residences. Much of the time you have to fix up the fabric of the building too, and often those repairs are extensive and require serious restoration carpentry. Restorers need to be very experienced in old buildings, as well as in jacking, sistering, scarfing, and shoring, among other fairly old-fashioned technique. You may need to repair a foundation or sister in new studs, or wreck out an old sill and scarf in a replacement. These are advanced skills not often found in the repertoire of run-of-the-mill (pun intended) Maine framers.

So there's no viable shortcut to energy retrofit of old buildings in Maine as a result. Energy auditors need to know a lot about buildings, and energy retrofitters need to be able to either repair old buildings themselves, or know enough to call in the services of someone else who can do the work. It was easy enough to demonstrate this with our old house, which has had much of this kind of work done over the years we've owned it, some of which can be seen in the basement and attic, some in pictures we've taken.

The old place is now, after much labor, exceptionally cosy and efficient for an older home, and only uses two cords of firewood, perhaps 1500 kWh of electricity and fifty gallons of heat oil at this point. (When the previous owners had it, it used 700 gallons of heat oil, ten cords of wood, and an unknown amount of electricity.)



Hi Mick,

I'd just like to thank you for hosting us last week at your home and campus. We learned a lot about how to approach a building retrofit. I especially appreciate how you stressed the importance of knowing a buildings age--a simple fact to figure out, but it clearly has huge implications on the recommendations and approach we would take.

On that note, on the car ride home we came up with one follow-up question. You mentioned that most Maine buildings fall into three modes/time periods of construction. The first one was the balloon frame style from the turn-of-the-century farmhouses. What were the other two modes?

Again, thank you so much for taking the time out of your day to meet with us,  

College of the Atlantic
Bar Harbor, Maine, USA 

and my reply,


The oldest frame buildings in Maine are post-and-beam, modified from their British islands originals primarily by the use of wooden studs between the heavy posts and clapboard siding, rather than wattle and daub. This because there was much more timber available in colonial New England. Very often their posts and beams and studs have unmistakeable tool marks from hand-hewing, hand-sawing  in a “saw pit", or vertical “sash” power saw mill work, as well as “blacksmith” or square nails. Typically these were water-operated sash mills. Unity had several such mills at one time.

When more efficient circular saw mills were developed, and nails could be made by machines instead of by a blacksmith, the older type of stud construction called “balloon framing” evolved, generally just before and after the Civil War. Some houses, like my own, incorporate elements of both techniques (even as late as 1900 — carpenters were not always quick to adopt new ideas). Balloon framed homes under retrofit for energy efficiency must always be retrofitted with fire protection, if they have not already been, either by adding firestops to stud bays or by the use of fire-suppressant insulation. Balloon framed houses often have “let-in” cross braces because they are sheathed with one-by boards, not plywood panels. If the let-in braces were not effective, because of poor execution of mortices, etc, these houses tend to “rack,” i.e., lean over, to make a parallelogram instead of a square building. Most racked houses seen in Maine towns are balloon framed.

By the 1940s and 1950s, with the advent of cheaply available plywood and other engineered wood components, balloon framing was abandoned in favor of “platform” construction. A more efficient modern form of platform construction uses six inch studs instead of four, now required by law in Maine. This can be greatly improved with two more inches of stud bay insulation, and foam board insulation over the sheathing. The foam board can be placed under the sheathing if let-in braces are used. This is what I did with my extension.

Modern variants of post and beam construction use “SIPs”: structural insulated panels. These save the need to fill in between posts with studs.

The Terra Haus uses both a platform framed interior load bearing structure, with six-by studs, and an exterior eight-inch SIP envelope, essentially tripling the wall insulation. This technique was pioneered by GO Logic, the Belfast, ME-based design-build firm that built it. I’m not sure how far this idea has or will spread, but it solves some important problems in energy efficient architecture.



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