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Solar wall heaterEric D. Hart erichart at mtn.orgTue May 13 22:42:34 CDT 1997
At 02:20 PM 5/8/97 -0700, Will Firstbrook WCB of BC wrote: >The idea is to use the sun to heat the exterior of the southern exposed >cob walls. This could be accomplished by imbedding some glass on the >southern exterior side of the structure and leaving a small air pocket >between the glass and the cob. The cob would be painted/stained/dyed >black for maximum heat absorption. This should transfer quite a bit of >heat into the cob depending on how big this glass is and how much sun is >available. If little sun is available the glass and air pocket provides >a little insulation for the cob. In the summer if it gets very hot, >shutters could be installed to minimize heat absorption; Or an overhang >could be designed to allow winter sun to heat the window yet shade the >window from the sun in the summer. > >A variation of this could be to build a solar oven into a south wall >near the kitchen with interior access. > >Does this seem feasible, or even worthwhile? I know this is essentially >the passive solar way of heating the interior through the windows to >heat an interior thermal mass wall. But at certain locations it may be >desirable to not have a window to the interior. From what I understand of passive solar design, the idea is to let sunlight into the house and heat mass *inside* the house, such as floors or an interior wall, instead of an outside wall. In theory anyway, the heat spreads throughout the floor and radiates after the sun goes down. Unless you had a very narrow house with direct access to the south facing wall you describe above, I doubt the south wall alone would be able to radiate enough heat reach all corners of the house. Besides I imagine you would like to have a nice view out those south windows and some sunshine in your house. You can calculate what sort of overhang you need to get optimal summer shading and winter sunlight. Methods like you describe above were used in the 1970's on the first solar homes and some of them are spectacular failures. One I looked at in Minneapolis has the entire south face of this two storey home in glass with *no* buffer between the glass and living space. Needless to say, they had to shade the glass during the summer and even then, it was routinely above 90 degrees F in the house. I don't have the references of good solar design books handy, but there are several and this sort of design has become almost mainstream. Eric D. Hart Community Eco-design Network PO Box 6241 Minneapolis, MN 55406-6241 USA (612) 306-2326 erichart at mtn.org http://www.tc.umn.edu/nlhome/m037/kurtdand/cen
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