solutions to downdrafts, Wofati

The wofati article did a great job in tackling the problem of water flow/drainage and the resulting dampness that can plague earth dwellings. 

But solving the water flow problem isn't enough if it exacerbates the air flow problem -- specifically the downhill drafts and thermal belts that swirl down and around a hill, as discussed and depicted by Mollison in his design course literature. 

The wofati structure, by facing uphill, would seem to invite a downdraft of cold wind right into the house with no escape.  The three-foot roof extension, while blocking rain, may well channel wind right into the structure. 

A solution might be to site the house within a thermal belt just below the keyline, but at the very least I think an exploration and discussion of this issue is warranted at this point.

Interesting!  You are correct:  I have given this zero consideration.

I have the big black book.  Can you site a page number?

Of course, in the summer this would be a very welcome thing.  So it would seem that the best solution would be to plant a bunch of bushes above the wofati that have leaves in the winter, but not in the summer. 

Okay, no such plant ....  In that case, some earthworks and some evergreens should do the trick, right?

Was that possibly part of the reason Mike Oehler suggested enclosing the uphill courtyard as a greenhouse?

Kathleen

Enclosing the uphill area as a greenhouse is a suggestion, yes.  And, now that you mention it, that would probably do a pretty good job of solving this problem.

Or, relating to the keyline positioning, make sure you have a belt of trees uphill from your structure.  The trees will moderate air flows through them and push air that is too warm or too cool up above.

paul wheaton wrote:
... it would seem that the best solution would be to plant a bunch of bushes above the wofati that have leaves in the winter, but not in the summer. 

Okay, no such plant ....  In that case, some earthworks and some evergreens should do the trick, right?

The landscape where I live dies back in the spring, and sprouts emerge in the fall.  Let me emphasize: things are brown through the summer, and green through the winter, overall.  There are whole guilds of such plants, although I admit they aren't bushes.

A plant that goes dormant in dry or hot conditions should be easy to find, maybe even one that drops its leaves and/or falls over.  Self-seeding annuals work fine in my part of the world, and that group includes some that may be particularly useful to keep in zone 1.  I might use perennial (blue) flax, and harvest it for fiber when the weather gets hot.

A particularly well-drained bed might help, and you would want to direct water away from that part of the property quickly anyhow.  The earthworks can be shaped to maximize the effect of this vegetation on airflow, and the effect of seasons on the vegetation, perhaps with inspiration from valve designs.

paul wheaton wrote:
I have the big black book.  Can you site a page number?

It starts on page 106 in the big book.  But the best discussion is in Pamphlet II of the Permaculture Design Course series.  You can find those on scribd if you don't have them.

bruc33ef wrote:
It starts on page 106 in the big book.  But the best discussion is in Pamphlet II of the Permaculture Design Course series.  You can find those on scribd if you don't have them.

Where is it you can find them? Could you give us a link?
Leigh