[Greenbuilding] On earth tubes

[John Daglish]

Bonjour bill,

Most passivhaus projects in Europe now if needing ground source heating/ cooling do
not use open air to earth heat exchange tubes EAHX but a buried tube
with a liquid heat exchange fluid such as a saturated salt solution. A liquid to
air heat exchanger is placed on the ventilation duct before the
HRV/ERV with bypass controls as necesssary.   Less installation
troubles, avoids mould risk but it does require a longer tube and its
efficiency losses are greater due to the heat exchanger.

We dont have cavity wall construction in France, but to not ventilate
the cavity was asking for trouble when using porous/water absorbent bricks. A double
check with a vapour movement program would have alerted the designer.

We do though have wood fibre insulation with a plaster finish (no
cavity) on insulated timber construction but it has a coating to
reduce water uptake.  Similarly straw bales have lime plasters. This
is not normally a problem unless subjected to a driving rain climate
without sufficient drying time in which case a ventilated rain screen
cladding is often used.

Cordialement

-- 
John DAGLISH
Paris, France


Thursday, June 7, 2012, 2:52:07 AM, you wrote / vous ecrirez:

bavn> Nick,

bavn> The article states that not all the facts are available but the author guesses the earth tube was not sloped for drainage and that there was standing water in the earth tubes. Clearly this
bavn> would contribute to their issues.

bavn> I'm trying a new twist on a small project....while I was digging the foundation for a small protected shallow foundation, I hit water...so I put in a usual 4" perimeter foundation drain (filter
bavn> cloth, gravel, pipe, etc.).  I sloped it down hill to day-light.  It will clearly drain well.

bavn> For fun, I put in a "T" in it to feed up into the living space to act as a source of air like an earth tube. I'm hoping I don't get sick....

bavn> Comments welcome....(But be nice).

bavn> Bill  
bavn> -----Original Message-----
bavn> From: "nick pine" <nick at early.com>
bavn> Sender: greenbuilding-bounces at lists.bioenergylists.org
bavn> Date: Wed, 06 Jun 2012 20:05:33 
bavn> To: <greenbuilding at lists.bioenergylists.org>
bavn> Reply-to: Green Building <greenbuilding at lists.bioenergylists.org>
bavn> Subject: [Greenbuilding] On earth tubes

bavn> http://www.greenbuildingadvisor.com/blogs/dept/musings/belgian-passivhaus-rendered-uninhabitable-bad-indoor-air

bavn> Nick 


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