Re: Common House ventilation systems
From: Robert Hartman (
Date: Thu, 2 Nov 1995 13:05:55 -0600
> Date: Tue, 31 Oct 95 09:22:55 CST
> From: "Fred H Olson WB0YQM" <fholson [at]>
> To: cohousing-L [at]
> Subject: Re: Common House ventilation systems
> Message-ID: <47415.fholson [at]>
> Jay Jacobson  jsj1 [at]
> is the author of the message below but due
> to a listserv problem it was posted by the COHOUSING-L sysop (Fred).
> ****************  FORWARDED MESSAGE FOLLOWS *********************
> Hi.  We (EcoVillage at Ithaca) have started infrastructure development and
> are finalizing our plans for heating/ventilation systems.  We'll have
> radiant floor heating for winter but the question is how to avoid
> overheating in summer when there's a lot of window area.  We plan on using
> vegetation for cooling but our consultant still predicts overheating.  Any
> advice on cooling for the dog days of summer when even opening windows
> doesn't help much?  Has anyone designed a ventilation system for exhausting
> heat overnight and drawing in cooler air?  

Well, those water-filled pipes that you'll be using for radiant heat
in the winter can be used for cooling in the summer.  If you are using
solar panels to boost the heat, you can add a pump and set the timing so
that the water flows through the panels only at night.  They'll "collect" 
the cold and radiate that through the floors.  Cold floors aren't much
fun first thing in the morning, but they're great on a hot afternoon.

One trick for both heating and cooling is to use thermal mass to
moderate the temperature changes, and to time how the mass is exposed
to the sun (or the night air).  So, you might consider adding an
aquarium or planter box in the place where the sunlight hits the floor
during the hottest part of the day.  Another thing you can do is
install a "waterfall wall," which will promote cooling by evaporation
all day.

When it comes to reducing the heat-generation of windows, the important
thing is to prevent the heat from getting inside the building, or to
get rid of it before the floor or walls can soak it up.  You can do that
by reducing the amount of light that strikes the windows in the first
place (with shade trees, awnings, screens, or mylar sheeting on the
_outside)._  The most effective device is probably full-length,
louvered wooden shutters set about 6 inches outside the windows.  You
can see out through the louvers, but they still block most of the
direct light hitting the glass.  You can vent any remaining heat that
leaks in before it gets into the floor using a thermal chimney.  The
simplest thermal chimney is a 12" tall strip of outward-opening windows
across the top of your bank of picture windows.  To boost the chimney
on the inside, you can use sheer curtains set about 6" inside the
windows to trap the hot air and guide it up to the vent.

Also, if your building has an attic, make sure there is plenty of
insulation between the attic and the ceiling and that the attic is
well vented.  Use white material for the roofing.  If the roofers
don't have any or want to charge extra, buy 20 gallons of whitewash
and spray the whole thing.  A black or dark roof acts like a giant solar
collector all day.  At night, it acts like a giant radiator.  A
white roof is much less conductive of temperature.


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