Dave Fawthrop wrote:
On Thu, 10 Aug 2006 07:37:09 GMT, Stuart Noble
wrote:

wrote:


|It is temp difference that
| causes condensation, not absolute temp (assuming we're talking above
| freezing). On a hot day the air can hold a lot of water vapour (the
| hotter the air, the more water vapour it can carry). If the hot air has
| highish RH, and meets a cold wall on wet ground, the 20C drop can cause
| condensation. Although summer condensation is less common than in
| winter, it does occur.
|
|
|I'm perfectly well aware of how condensation occurs thank you, but I've
|never seen it during a hot summer, and I doubt you have either.

The temperature of *dry* *internal* walls will approximate to the average
air temperature. (average over several days and both sides of a wall) In a
hot summer temperatures, this average temperature will be high.

I did some experiments and wrote a simulation of temperatures in masonry
walls, subject to air temperature changes, many years ago, but I can no
longer run the code.

As digital probe thermometers are now quite cheap, and available. It
might be a good idea to drill holes in the damp wall and measure the
temperature, at various depths. I will have to think about the effects of
dampness.


As masonry retains heat, I can't see where this 20C difference in
temperature the honourable gentleman refers to is going to occur. A damp
wall would be colder, but the source of the damp would not then be
condensation.
What was the purpose of your research out of interest?