Re: Passive cooling/Tucson
From: Racheli Gai (
Date: Tue, 6 May 2003 08:18:01 -0600 (MDT)
>From Racheli in Tucson.

I know very very few people who live in Tucson without
the assistance of (at least) evaporative cooling (that
is: among those who can afford to pay for cooling.  I'm
sure there are poor people who swelter because they don't
have a choice).  Relying completely on passive cooling means
you need to be able to bear real hot indoor climate in the
summer - hotter than most of us can bear.  (This is because
in mid-summer the temperatures stay high even at night).
Evaporative cooling works very well for part of the hot
season, but in July-August the weather here gets humid,
and we get "monsoons" - which render the evaporative
cooling fairly ineffective.
In Sonora Cohousing we chose to have air-conditioning.  This
is because we couldn't install two systems per house, and 
some people have health problems with evaporative cooling.

In a cooling climate, a major way to help cut on cooling bills is by
sizing the windows appropriately; by having large overhangs and placing
the windows in the right places (in terms of orientation, as well as
sufficiently close to the overhangs). These last things have not been done
quite right, so we use more energy for cooling than would have been
necessary otherwise. Using plants to shade is helpful, but isn't
applicable for second floor windows.  (Well, perhaps eventually my vines
will reach that height :)) 

>Here in Pleasant Hill we have a variety of passive cooling methods built
>in to avoid the need for central air. First is a metal reflective roof,
>then metalized insulation sheets under the roof, then 2 x 6's instead of
>2 x 4's giving thicker walls and more insulation. Most of us have whole
>house fans, to blow off the hot air and suck in the cool at night. We
>have double-paned windows and many have double-celled mini blinds which
>we keep closed in the heat of the day. There might be a couple things I
>missed, but those are the major ones.

>I moved here from SF, where it's always cool. Chuck Durrett promised us
>it would work, but I was not a believer till I saw it in action. I came
>home to my house each summer day (days it was often 90-100) out here, to
>a house that was 75 degrees cool (felt like air con) downstairs, and at
>worst 80 upstairs. Each night when it cooled off I ran my whole house fan
>for 1/2 hour, and cooled the whole place down. There were only 2-3 nights
>the whole summer when I was too warm, and that could have been fixed by
>getting my ceiling fan up in the bedroom!

>Chuck claims this works in places as hot as Tucson. I almost believe him!

racheli [at] (Racheli Gai)

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