Habitat for Humanity MV, energy, and affordability

The Town of West Tisbury recently passed the Stretch Code at Town Meeting. It's a more stringent building code and in essence it speeds up the adoption of the next iteration of the International Energy Code. Debate was spirited. Aginners (as in, I'm agin it) made impassioned pleas about how it was just another gubmint imposed tax on those that could least afford it, the working folks. My opinion is exactly the opposite - Martha's Vineyard's tax on the working people is $4+ per gallon oil and propane, and almost $0.20/kWh electricity. A tougher energy code is the worker's friend in the long run.

Next to those designed and built by South Mountain Co., the most energy efficient houses on MV are being built by Habitat for Humanity. They are dedicated to permanent affordability for their owners. In the past, HfH often was the recipient of donated products that were sometimes on the low end of energy efficiency, such as inexpensive windows and low efficiency heating and hot water equipment. On MV, the forward thinking folks who operate HfH are, with some detailing help from SMC, building super insulated homes that are very airtight. I help with QA, testing the houses with blower door and fog machine or IR camera. The first house at Bailey Park Rd. was 175 cfm50 at the stage of windows and doors installed and most of the roughing done, but no drywall. In the next month they'll be ready for a final test. Today we tested the shell at the second house they are building there, with window and door openings poly'd off. It was just about 300 cfm50 with the air barrier being one layer of taped polyiso foam on the walls and roofs. The house is a kit, which is all T&G pine inside, a potentially very leaky strategy.

With volunteer workers, they're building a house tighter than almost all the pros do here. The beneficiaries will be the owners. The mechanical system is mini split heat pumps, far less costly to operate than fossil fuel equipment. Thanks, Habitat, for leading the way to permanently affordable housing.

 

 

 

Comments

[dana]

I'm curious as to how they're insulating the basement/foundation for this house? I would think air-sealing the floor would be more difficult and less reliable over time than insulating and air sealing the foundation walls. Is there a target design condition heat load they are working from?

[Marc Rosenbaum]

The basement is insulated both sub-slab and on the interior of the basement walls.

[brad]

I am looking to discuss a whole house renovation of a 1858 farmhouse that will be a deep energy style retrofit. I am in the process of buying an old farmhouse down the street from me, that has been partially deconstructed. Having been a builder/carpenter of fine homes for over twenty years I may now have the chance to do it right for myself, and of course for my kids, and mother earth.

Having read many published articles I am full of questions. Like why foam? Seems as though many of your best building practices currently advise to use foam, foam, foam? Is it TRULY healthy for us? Why not rigid Roxul insulation? I have seen in many, many instances where foam suffered intrusion by pests, and bugs, and ants. Even with the higher R-values and vapor permeability being better the wool insulation, isn't the wool insulation healthier, more breathable, and maintains R value consistently over time? I was obviously hoping to use wool insulation in my Larsen truss style walls, roof cavities, and on my exterior foundation....but you have me second guessing myself??????

How would you detail a foundation with 160 year old hemlock sills and floor beams?

I have included a link to some section views I have done that further outline my questions at the links below.
https://picasaweb.google.com/brad.hardie/PoplarPlans?authkey=Gv1sRgCI3_oqin3I-NAg

Check out the pictures of the house I'll be tackling here (these are it's current condition in which I am buying it)

https://picasaweb.google.com/brad.hardie/PoplarStHouse?authkey=Gv1sRgCKi4gIyDub3oFQ

Your help, advice and guidance would be greatly appreciated.

Respectfully,

Brad

[C-Mech]

Great to see the use of air barriers in residential homes. It’s great to see it being pout to such great use, but the universal use of air barriers doesn’t stop there. They have great potential in commercial ventures, such as food storage and preparation. The energy saving qualities alone are usually enough to warrant an investment, but the practical applications, in such cases as food storage make it a no brainer.

You’ve gone into great detail, and this would really help someone relatively new to the subject.

Great work.