Cob RE: Different types of heating.

[Michael Saunby]

On 26 December 1998 19:54, Mike Carter and Carol Cannon 
[SMTP:cobcrew at sprynet.com] wrote:
> A greenhouse (glasshouse) achieves temperatures way in excess of its
> surroundings with no heating so this idea of a building with high thermal
> mass achieving the mean of it's surroundings is surely untrue - it might
> ...
>
> How can you prove anything about high mass buildings by using a 
greenhouse
> as an example?

It wasn't meant to prove anything other than to point out that a building 
with no heating other than solar radiation does not always have (ever 
have?) the same mean temperature of its surroundings; there are other 
factors at play.  It could be warmer on average like a greenhouse or even 
cooler.

> In our cooling climate, our building (130 tons of mass)
> really does even out the temperatures.  This is achieved through 
techniques
> that minimize solar gain except through the walls.  The windows are kept
> shaded, in general, if they face South or West.  The window area is 6% or 
so
> of wall area instead of the customary 11% or more.  Ventilation adds to 
the
> stability of temperature.  Remember also that at night there is 
compensating
> radiation out the window glass, and the closer you are to the equator, 
the
> longer the summer nights are.
>
> I agree totally with your other points on insulation.  The very well
> insulated strawbale houses here have mechanical HVAC because of the 
points
> you raise - once the interior gets hot (through solar gain through 
windows,
> for example), there is no way to cool it down except mechanically BECAUSE 
of
> the good insulation.  Whereas the conductance of our cob walls prevents 
the
> heating of the interior air much beyond the wall temperature.  The walls 
in
> fact "set" the air temperature.
>

I think it's fair to say that these (modern) days, it's easy and cheap to 
provide insulation, heating is rather more expensive (thanks to taxes, the 
need for large corporations to both generate profit and grow, etc) but 
comfort is not something that is determined purely by temperature and many 
aspects of a building determine how comfortable it is. e.g. quality of 
light, sound proofing, ventilation, colours, textures, smells.....  Earth 
has many qualities, though it's true that insulation isn't one of its 
better ones.

> Thermal mass works.  People have known this for thousands of years.  It 
will
> even out the diurnal temperature swings.  If the exterior temperature is
> always cold, then you are going to want to make your walls thicker and 
add
> some "outsulation" to increase the efficiency of your supplemental heat
> source.  South and West windows that you cover at night won't hurt, 
either.
>

I agree.

> Mike Carter & Carol Cannon
> cobcrew at sprynet.com
> http://home.sprynet.com/sprynet/cobcrew
> Austin, TX    USA
>


Michael Saunby.  Devon, England.......