On 16/06/2014 15:50, Andrew Gabriel wrote:

Well known problem with many modern houses - they have no internal
heat capacity, and so only a small amount of energy getting in
causes a significant temperature rise. Lack of loft insulation
would make it very bad (radiating heat from the hot ceiling), but
even with loft insulation, it can be a major problem.

I have two loft hatches - the summer one has a 10" Expelair fan
mounted in it. This was originally done for another reason - I had
some computers in there when I worked for Sun, and it was to try
and stop the temperature up there climbing over 40C. Computers
long since gone, but I still use it to help cool the upstairs if
it gets hot.



I have very high levels of wall & loft insulation (sprayed in 450mm
Warmcell)
The issue is as you say it gains heat during the day and being
Timberframe internal (brick external) it does not lose heat easily.


The outerwalls are also like huge heatsinks ...walk past outer S & W
wall in evening after sunny day and wall is putting out tons of heat ...
I know this is outside, but it does mean warm inside rooms even more
difficult to lose heat.

The fan on loft hatch is almost same thing .... just whole house fans
take it a little further with opening shutters & remote speed control

The only loft access is ion sons bedroom he may not like noise of fan ..
so a ceiling mounted extract above stairwell may be answer.


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UK SelfBuild: http://uk.groups.yahoo.com/group/UK_Selfbuild/