[Cob] Straw bales vs ?

[GlobalCirclenet]

Agree application has much to do with practicality. Strawbale may be
practical for storage or animal outbuildings where it's easily available
and doesn't have to last long. As for heat loss, walls versus ceilings,
most heat loss is through the ceiling because heat rises, all other things
being equal. Of course extra insulation in the ceiling narrows the
difference (and adds to the cost), and constant opening of doors and lots
of windows would affect the relative heat loss.  I agree that "highly
insulated homes (regardless of insulation type) lose far less heat, and
lose it pretty much uniformly across the walls and ceilings, where poorly
insulated buildings lose alot more heat, and lose most of it through the
ceiling." If highly insulated means much more insulation in the ceiling
than walls.  My original point was that strawbale walls don't do anything
about the major heat loss which is through ceilings, doors, and windows,
and that stopping those losses costs just as much as any other type home.
And that for any sizeable home it's obviously impractical to support
strawbale ceilings with an expensive grid of massive timbers or glulams and
support posts. 

paul at largocreekfarms.com
http://medicinehill.net

*********** REPLY SEPARATOR  ***********

On 7/21/2004 at 12:39 PM David Knowlton wrote:

>my friend the engineer would say that the 'application' is
>what determines the practicality of different building methods.
>
>for example: stone and brick are not commonly used in florida -
>we don't have those things locally. we do have wood and concrete.
>
>we also have very high ground water levels - making basements
>quite unpractical here - not impossible - just impractical.
>
>david
>
>
>>From: "Shannon C. Dealy" <dealy at deatech.com>
>>Reply-To: dealy at deatech.com
>>To: GlobalCirclenet <webmaster at globalcircle.net>
>>CC: coblist at deatech.com
>>Subject: Re: [Cob] Straw bales vs ?
>>Date: Tue, 20 Jul 2004 20:48:59 -0700 (PDT)
>>
>>On Mon, 19 Jul 2004, GlobalCirclenet wrote:
>>
>>[snip]
>> > bales.  The strawbale fad is wildly impractical for a house because
>80% 
>>of
>> > heat loss is through the ceiling, and that's not counting doors and 
>>windows
>>[snip]
>>
>>The high relative heat loss through the ceiling is only true on more
>>poorly insulated houses, as the R-value increases uniformly throughout
the
>>walls and ceiling, the heat loss per square foot of the ceiling
>>relative to the walls decreases until it becomes virtually uniform.  I
>>don't remember the numbers, but I think it was around R-40 or R-50.  The
>>reason for the difference is that poorer insulation levels (particularly
>>in the ceiling) generate stronger convection currents in the house, and
>>the stronger the convection current, the faster the heat is transferred.
>>
>>There is a little more to it, but what it boils down to is that highly
>>insulated homes (regardless of insulation type) lose far less heat, and
>>lose it pretty much uniformly across the walls and ceilings, where poorly
>>insulated buildings lose alot more heat, and lose most of it through the
>>ceiling.
>>
>>
>>Shannon C. Dealy      |               DeaTech Research Inc.
>>dealy at deatech.com     |          - Custom Software Development -
>>                       |    Embedded Systems, Real-time, Device Drivers
>>Phone: (800) 467-5820 | Networking, Scientific & Engineering Applications
>>    or: (541) 929-4089 |                  www.deatech.com
>>
>>
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