Building Performance

Traditional framing and building practices, using wood, stone, straw, clay.
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Chris Hall
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Location: Greenfield, Massachusetts
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Re: Building Performance

Mon Mar 09, 2015 6:55 pm

"In the mild climate of the NW our newly built house - 1350 sq ft living space - costs around $90 a month to heat during the coldest month - heat being natural gas, radiant floor. Conventional framing, double insulated windows - old school 15 lb felt vapor barrier. Around $130 sq ft to build... I am just wondering how extra money spent on insulation upgrades would have paid off with energy costs in our climate?"
Well, for point of comparison, our house in North Western MA (definitely colder then where you are), also about 1350 square feet, has doubled wall framing 12" thick, heated by natural gas, cellulose infill, and the highest monthly gas bill we have had was $54.00. We use the gas also for cooking and heating the hot water, so we really don't use much for heating. We're probably a bit more frugal than most in that respect. We also have solar electric, and tend to use a small electric oil space heater in the den where we spend most of our time. It is great having low utility costs. In the summer our gas bill is $15~18/month. And we've never had an electric bill.
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Steve
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Re: Building Performance

Mon Mar 09, 2015 7:29 pm

Wow, that is amazing! Do you burn any wood at all? What was the square ft cost for the construction? (ignore that question if you want - I don't meat to pry)
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Chris Hall
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Re: Building Performance

Mon Mar 09, 2015 7:59 pm

We don't burn wood, though I would like to do so.

Construction costs were around the same as your place I think. I didn't have it built specially- we found it on the market and moved into a new house.
Matt J
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Re: Building Performance

Mon Mar 09, 2015 9:58 pm

Ernest- I didn't know about the mountaineering origins of modern vapor control membranes. Interesting! I assume you're talking about the high tech stuff like Pro Clima's Intello...https://proclima.com/products/internal-sealing/intello and others coming out of Europe.

It's worth noting that low tech materials can also be used as vapor retarders- the kraft facing on common fiberglass batts is actually a good one (it's just not a good air barrier, and FG batts are notoriously prone to poor installation). Latex paint on drywall, and cdx plywood also have good properties for vapor control.

I think you're right about the energy displacement idea, to a point. The energy consumed by heating and cooling a typical code built house over the life of the building (in the United States) usually dwarfs the embodied energy of the materials and construction process. But as the efficiency of the house increases, those initial embodied costs become a larger percentage of the building's overall energy (or carbon) footprint. Of course, the numbers will vary for different occupants and different climates.

I'm with you on wearing a sweater!
Matt J
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Re: Building Performance

Mon Mar 09, 2015 10:51 pm

Steve- the financial case for above-code levels of insulation can be tough to make even in cold climates like New England. Most of my clients do it for other reasons, like increased comfort, resiliency, or because they're an 'environmental crusader' out to make a statement.

It's impossible to say what kind of returns could be realized in your house without knowing all the nitty-gritty construction details, climate, solar orientation, and usage patterns, etc. of your house (Out of curiosity do you have a blower door number?), Not to mention labor and construction costs in your area. It sounds like you're at a reasonable balance point of cost/vs performance. But consider that your house will likely still be around, with much the same efficiency, in 25, 50, or 75 years, and nobody knows what the cost of energy will be by then. Given that the cost of retrofitting insulation is drastically higher than the incremental cost in initial construction, your house's occupants could someday wish it was constructed differently.

Please understand I'm not trying to trash your house or decision making... I struggle with this all the time. It's really easy to throw a lot of money and energy into a project and not achieve good performance.
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Steve
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Re: Building Performance

Tue Mar 10, 2015 12:07 am

Good question about the blower door number - in our state it is a pass or fail test for new construction. The building passed but I am not sure what the number was. Our energy usage was pretty extravagant this winter - lots of long showers and very snug nights. The winter of 2013 (while the house was being built) was spent in a old farmhouse with wood heat and a puny little water heater, so we have been really living it up this winter.
ernest dubois
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Re: Building Performance

Tue Mar 10, 2015 5:05 am

Hi Matt, I probably should have put it something more like, developed its wide spread or expanded application. The connection to mountaineering is interesting because so many of these climbers relied on construction jobs to pay for climbing.

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