[Cob] New, climate questions

[Jamie Carr]

So...how excessive is 1250sq ft for 4 people? As a cob house I know that's huge (small for most of the country though) but we do have a family, and I cook a lot and we eat together so spacious kitchen and a dining room is a must. I would close those off at night and try to only heat the LR and BRs, 680sqft.

As far as passive solar goes, I'm already planning the most and largest windows for the southern side and a good roof overhang to block some summer sun. In my current home I close my heavy cotton curtains on summer days and winter nights. The bubble wrap idea is neat, one could even hide it inside normal curtains. Not letting the children pop it might be a challenge...and resisting the urge myself lol. I was unfamiliar with glazing so I looked it up and found some info on using higher heat gain windows on the south side to let in more winter heat, lower elsewhere. I have to wonder even with roof overhang if that might sacrifice summer comfort if I can add heat but can't cool this house. I don't really want an in-floor heating system, too much cost I'm sure.

Anyway, I expect I want 24" walls, I need many of them straight for the look I want so I can't skimp on the thickness. I might need buttressing in places too. 14" sounds very minimal even just structurally, I assume yours is a small house with lots of curves in the walls? I want an earthen floor and a cob couch and woodstove surround. The thermal mass of this place will be excellent so once we have a good temperature it sure will stay there. Not sure if the subfloor should be insulated or just have lots of gravel and sand for drainage, the deep earth here is like 50F so that's good to let through, right?

Self sufficient resources are high on your priorities list I see. I think I'm going with solar power, propane range and fridge, woodburning stove for heat. The pellet ones I'm told are more efficient but I'll have my own little forest so maintaining it will provide lots of firewood. If the fuel prices soared I could switch to a wood cookstove and small electric fridge or just a root cellar at some point, and outdoor cob oven. A greenhouse, chickens and sheep are in the longterm plans (a few years after I build the house) but for now and near future it'll be perennial fruit bushes and trees, cultivated mushrooms, and direct seeded garden (beans, peas, lettuce, greens, squash, carrots, herbs) plus whatever I can start in my nice deep windowsills. Been growing a few veggies here in my little yard in the city so far, enough to feed us through the summer mostly.

Thanks,
Jamie

--- On Wed, 6/22/11, Ron Becker <ron45 at tularosa.net> wrote:

> From: Ron Becker <ron45 at tularosa.net>
> Subject: Re: [Cob] New, climate questions
> To: "Jamie Carr" <kfmaille at yahoo.com>
> Date: Wednesday, June 22, 2011, 5:00 PM
> Thermal mass just slows down heat
> transfer enough to make an inhabited, properly sized
> structure easy to keep comfortable. If you don't already
> have it get The Hand Sculpted House by Evans Smith and
> Smiley.  Proper sizing of your living space is crucial.
> I didn't know about the concepts in this book when we built
> our adobe starting in 84. Our adobe has 14 inch exterior
> walls. This is at least 10 inches short of ideal.  It's
> also too large for two people. The concepts in this book are
> crucial to making a cob cottage work for you. Cob in and of
> itself doesn't necessarily incorporate passive solar
> heating. It should but it got it's start in this country in
> the Cascades in Oregon or Washington I forget. Not a lot of
> reliable sun there.
> 
> The key to making passive solar heating work is proper room
> shape and size with the proper amount of glazing for the
> square foot area of the space behind the glass. It's not
> rocket science but its very important. Another key is to
> have a way to insulate the glazing at night. Thermal mass
> plays a roll here but reducing heat loss thru all the glass
> at night is icing on the cake.
> 
> A really inexpensive and practical way to do this is with
> bubble pack curtains. We tried this as an experiment and
> were delighted. We used ponderosa logs as the vertical
> supports where the glazing is. These are irregular [ non
> dementional lumber ] so many thermal curtain options were
> not practical for our situation. There are pics at the
> myspace link if you click on photos. Because these are logs
> with a flat spot for the glass, the bubble pack goes between
> the round shape of the log and the patio door replacement
> panels and just stays there. There is a piece of 1/2" pvc
> filled with sand at the bottom of each curtain that keeps it
> against the glazing and makes it roll up and down like a
> bamboo curtain with a bit of string ingenuity and some
> pulleys.
> 
>  We planned to cover them with material but we liked the
> all the light that came thru when we had them lowered on a
> cold cloudy day. We never need lights on till after sundown.
> The trade off is you have to replace the bubble pac every
> three years or so. I found a place on line that sells many
> sizes of bubble pac that were unavailable to us locally.
> With smaller bubbles you can double the length of the stuff
> for each curtain and you have two dead air sheets and the
> diamond shaped spaces between the bubbles on each half of
> the curtain make another dead air space if you seal the
> edges and I believe they will perform better then the single
> sheet of 1" stuff we use.
> 
>  It's not for everyone but it works very well with a small
> money outlay. I'll provide the link if you decide to give it
> a try. It also goes in our sky lights as many layers that
> still pass light but not heat in either direction. In summer
> we keep the curtains down during the day and raise them at
> night. It makes a big difference even if your glazing is
> properly shaded for summer. There is still a large amount of
> very warm air against the R2 glazing. Induction never
> sleeps.
> 
> 
> We are at 7k feet in New Mexico and it got to 11 below here
> last winter and can stay in the 20s till the sun goes down
> on some sunny days. If you incorporate passive solar heating
> ideas into a home with adequate thermal mass there will be
> plenty of winter mornings when, if you just put on an extra
> shirt or sweater,  you don't have to build a fire if
> you had one the evening before or during the night. But
> there are too many variables for blanket statements.
> 
> If you have enough thermal mass to expose to enough heat in
> a properly sized living space you are in good shape for not
> burning up excess resources to just keep warm. Cob in wet
> climates can work well but then you need rocket stoves or
> some other efficient heater [ not a pellet stove, when the
> Matrix goes down those will be useless, no gas to move the
> pellets and no juice to run the auger and fan, stay away
> from those] low tech heat is a must because you won't be
> able to count on reasonably priced propane or natural gas no
> mater what they say to the contrary. The people hyping
> natural gas as the next big fix are trying to get investors
> involved. Fracking is a nightmare of bad ideas and there
> isn't as much as n.g. they claim and it's going to be hard
> to get when enough people find out what a horror the
> extraction process is. Vermiculite is cheap and easy to mix
> into cob, paper crete is a possibility, as well as the other
> options you mention for enhancing the heat retention of a
> north wall. Almost forgot. Look into solar heated radiant
> floors if you don't want to do passive solar glazing. Good
> luck.  Oh yea, you better plan on a green house. As the
> price of gas goes up food will get to be a luxury item.
> 
> Ron
> Living and playing outside the box.
> 
> http://www.myspace.com/ron45becker