How long have you been doing this kind of "green building"?
I'm curious about the costs regarding a straw bale home. What was the cost per square foot for the project shown on the Killaloe straw bale home on the portfolio page of your website?
The passive-heated solar, and active-electric solar, two story post and beam (see How to build a Straw Bale Home on the Resources page on this website), with straw bale infill, was build with superior insulation throughout, (R-70+ in the roof, R-40+ in walls, and R-30 entirely surrounding and completely under the foundation and poured floor, with a 4 foot horizontal skirt of outward, buried frost protection ).
I list its' attributes because when one hears of a "cost per square foot" for the construction, one tends to immediately compare costs to standard frame construction. It is best to compare Straw bale costs to super insulated, staggered double studded frame walls with similar insulation values, air permeability & convection values, and extra large roof overhangs, like R2000 construction.
That being said, this project in 2003, including everything, from property purchase, building permit fees, excavating, solar electric system, composting toilet and grey water system, brand new airtight cookstove, solar and wood burning hot water systems, to include finish staircase, finished floors, and a base coat of primer .... includes all these details in the price of $140 per square foot of Interior Usable Floor space, (not the exterior foot print and dimensions). Of course now, many years later, the costs of building any type of home, including straw bale, have increased.
Is this building supplementary heated? What are the heating costs?
The owner has made insulated window quilts for every window (19), which she delights in opening and closing, following the sun around the house, from east to south to west. Thus she conserves her heat, way more diligently than most of us might. And her typical heating cycle, is to wake up in the AM to about 15 to 18 degrees C, and lighting a fire, or rekindling last evening's coals, if any. She fires her cookstove briskly, for one or two loads of wood, and allows it to go out by afternoon at the latest. In the evening, she fires again for one or two loads of wood, and lets it go out. Basically, she heats this house with two, hot fires per day. On average, this home is heated with about 6 face cords of wood per season. At $70 a face cord, this amounts to less than $450!
What was the cost of the solar components of this home?
Her solar components amounted to between 18,000 to $19,000, as her electrical usage in very conservative. In our home, when the solar components were installed, we had a 4 person household with lots of laundry, TV, DVD, and computer usage, we required approximately twice as much equipment, including a Whisper 1000 wind turbine, to produce our electrical needs. Fortunately, in recent years the costs of most solar equipment have significantly decreased in price. Now, this same $18,000 system would cost considerably less.
I am looking to build an off-grid solar Straw bale project in several years, a 4BR home for 3 kids and two adults. I am looking at a 2000 sq. ft. project, timber framed, passive solar with some active and perhaps wind. What would this cost?
If you use a rough estimate of $160-$200 per square foot, you won't be far off. Building Straw bale homes are labour intensive.
It may sound discouraging, at even say, $130 per square foot, the approximate cost of a conventional home, as that is still $260,000 from start to finish. The economics of sustainable dwellings look good when one considers the overall life of the home, or at least to take into consideration a full generation's use of the facilities. Considering a minimal heating bill, using renewable firewood, and considering the electrical and domestic hot water bills as being 'paid-in-full', in advance, for that period of time, then the balance begins to make some sense.
In other words, Straw bale construction costs similar to conventional frame construction, though the labour factor can be higher, due to details around plastering, and subsequent interior finish carpentry. However, the quality of life, comfort and sense of energy independence of a sustainable home is well worth the expense and effort of any amount.
You may consider building over a longer term period, adding electrical equipment as you can afford it. And by doing a lot of the labour yourself, and working up some good work bees for certain stages of the building, you could save a up to a third of the price.
How does your wood-fired domestic hot water set-up work?
In the photo, on the sustainable homes page of this website, the hot water tank is just visible above and to the right of the cookstove. (you'll see two vertical copper pipes in front of a white 40 gal standard hot water tank) In this case, the kitchen cabinetry is built around the hot water tank to camouflage it somewhat.
The cold water runs through a fabricated rectangular loop that is situated inside the firebox, just below the top-loading lid. This unit is made from 1/2" stainless steel threaded pipe and stainless steel hydraulic fittings. From there, the water passes through a series of 3/4" copper pipe that "snakes" back and forth outside the firebox, in the back of the stove. This portion is highly insulated with fireproof woodstove insulation and covered with a fabricated steel casing, painted to match the stove itself. The water is then deposited into the 40 gal holding tank above.
With the hot water tank positioned higher than the heating source, the system utilizes the principles of gravity circulation and no electricity is required to pump the water. The combination of internal and external heating provides sufficient, (in fact, excess!) hot water for our family, for about 6 months of the year.