Weeks 15&16

Since there wasn't that much to report or document on the house in pictures, I thought I would start off with an evening at Charlotte Beach, the picture symbolizing the near completion of this building adventure.

The errant windows arrived and were quickly installed enabling the completion of the siding attachment.  Inside the wall board or dry wall hanging was finished one week and the plastering was finished the following week, being executed by a real artist.  The stove pipe was also installed with the help of Balky, the lift, that had been behaving since it obtained a new joystick.  The "parging" of the part of the basement wall protruding the soil was started.  This process consists of adhering multiple layers of various materials to the insulating foam surface to result in a weather resistant cover.





 The Habitat for Humanity House

I had mentioned some posts back that Habitat for Humanity has been building two houses down the road that are designed to meet the Passive House energy standard.  The first house is a conventionally constructed one whereas the second one is prefabricated.  As with all their houses, much donated material and labor goes toward their completion.  These houses are being built under the guidance of Project Directors Peter Schneider from Efficiency Vermont and Architect John Clancy.

This design does not have much thermal mass but relies on much insulation to stem heat flow.  Observed under the basement slab was 10" of "blue board" foam insulation .  The walls are conventional 2" x 6" construction with 6" of foil-faced TUFF-R isocyanurate foam boards on the outside and cellulose insulation on the inside.  The roof has a truss construction that will allow around 30 in. of cellulose insulation. The goal is to have R100 in the roof and the basement with around R80 in the walls - if I remember correctly.  The windows are triple pane from Thermotech.  There is no website yet detailing this project even though the designs are being evaluated as standard future designs for colder climates.  The recipient of one of the houses, however,  is keeping a blog.

The house will be more conventional in appearance than my house and definitely more livable for a family of four.

More Energy Discussion
Did I mention last time that my low ball estimated energy consumption of 6700 kWh is only 84 kWh/m2-hr which is 30% better than that vaunted German Passiv Haus standard.  Of course, I've not accounted for some of the heat losses yet, so for now this is only numbers in cyberspace not real life living in my Haus.  Tune in on the real story next year.

This week we will see how the total heat cost will be "covered'.  By covered I mean how will the estimated annual need of 6700 kWh heat be produced?  Options around here are propane gas, electricity, wood, coal, or oil.  I've already said that I'd like to use as little fossil fuel as possible which eliminates propane, oil, and coal, leaving wood and electricity.  Of course we all realize that wood needs to be cut, transported, chopped, and delivered which right now is done with oil powered equipment.  Electricity in our area of Vermont comes largely from two sources, 47% hydroelectric, mostly  from Quebec Hydro, Canada, and 42% nuclear from Vermont Yankee which may be or maybe not be shut down soon depending on which way this political football bounces.  My intention is to try to minimize electric use by producing much of it myself with solar PV arrays and use wood as backup heat for the colder periods of the year and for power outages, though they have been rare.

Wood heat isn't cheap if you add the cost of a chimney and a nice stove to the cost of the fuel.  My Bari stove can generate from 12K-30K BTU/hr. which is much more than my hourly needs of 9520 BTU/hr on a zero degF (-18 degC) day.  Because the stove has a soapstone liner which gives it around 50 BTU/degF thermal mass, it should be able to moderate its heat output a little and hopefully the thermal mass of the inside of the house estimated to be greater than 15000 BTU/degF should be able to further moderate the emitted heat from the stove for short burns as it will take about an hour of burning to raise the temperature 1 degF... approximately.  After the stove no longer emits heat it should take about two hours to see a 1 degF temperature decrease .... approximately.

So how much energy can one get from a pound of wood?  In the laboratory one can get about 8600 BTU/lb.  After subtracting the energy required to vaporize the water content (20%)and taking the burning efficiency of the stove into account, maybe half that amount of energy can be recovered.

All wood, regardless of species, has about the same energy per pound.  The different species vary only in density.  A cord (128 sqft) of white oak wood  for example has about 30 MBTU (approximately 8800 kWh) which would more than cover my annual expected usage of 6700 kWh. Thus as a backup heat source, a half cord/yr may be enough.

Next time we'll look at the solar energy options for fossil free energy.

Please send me comments that add to the discussion and correct any errors of comprehension.