[Strawbale] Re: Glass bottle insulation and ISBBC 2004

namadgi namadgi at club-internet...
Thu Nov 24 14:45:34 CET 2005

hi rikki

i recently used old-fashioned (thick-glassed) wine bottles under the floor
slab in the house i'm building in the loir valley. i have no knowledge of
technical information about its insulation properties, but it seemed like a
good idea to me, air imprisonned in the bottle serving as insulation.

i know of a builder in the south-west of france who has used them and say's
that a layer of bottles (lying on their side) neutralises heat loss through
the ground (which amounts to about 10% of total heat loss from a building,
the majority going through the roof).  i also discovered that in the past
wine-growers in the region put down their "déclassé" wine bottles as floor
insulation covered with a lime floor in their wine cellar-caves. having
several thousand such bottles (all empty, alas!) in a old wine cellar-cave
on our land i decided to put them under the floor.....  (bear in mind you
need roughly 50/60 bottles to fill 1square metre!)

i sandwiched the bottles between a thick bed of gravel (indispensable in
this part of the world) and a lime concrete floor slab. pouring the concrete
over the bottles (use wooden planks) called for some fairly ... balletic

you talk about using them under an adobe floor. considering that an adobe
floor must be "rammed", ie flattened as much as possible (unless you have a
different technique) then i think bottles perhaps ought to be avoided. i
good bed of gravel to provide drainage covered with a geotextile (to stop
the earth filtering down) and 10/12 cm of earth slab - on two passages -
ought to do the job.

good luck,


----- Original Message -----
From: "Faas, W." <w.faas at student....nl>
To: <strawbale at amper....muni.cz>
Sent: Wednesday, November 23, 2005 1:57 PM
Subject: [Strawbale] Re: Glass bottle insulation and ISBBC 2004

Dear Rikki,

I don't think glass bottles make very good thermal
insulators. This is because of two reasons:

1. Glass has a high thermal conductivity -> thermal
2. The air in a bottle will probably start flowing with
temperature differences -> convection which transfers more
heat from warm to cold.

If you really insist of using glass bottles and don't mind
still getting a bad performance, I'd smash the bottles and
put down a layer of shards, add an airscreen to prevent
airflow through the construction, put down another layer of
shards, etc. Personally, I'd spend just a little more money
(and probably less effort!) and lay down a proper layers of
airtight insulation material. But then again, I'm in cold
Holland and if I remember correctly you're in warm Spain,
right? So you probably don't need as much insulation as we
need here.

About the ISBBC: Last year in beautifull Denmark, there
were plans to organise the next ISBBC in Canada somewhere
in the autumn (after the baling-season). Although that's
still a year away, I'm curious as to wether or not people
have been brainstorming/thinking about it already.


Walter Faas

    European strawbale building discussion list

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