On Fri, 23 Jan 2004 14:00:37 -0000, "IMM" wrote:


"Andy Hall" wrote in message
news
On Fri, 23 Jan 2004 12:16:54 -0000, "IMM" wrote:


"Andy Hall" wrote in message
.. .
On Fri, 23 Jan 2004 11:41:24 -0000, "Neil Jones"
wrote:


"IMM" wrote in message
...

"Neil Jones" wrote in message
[snip]

Total losses for house = 12.3kW

Downstairs losses are 51.9% of total losses from house.

Losses through:-

Ground floor 4%
Downstairs solid wall 19%
Downstairs cavity wall 1%
Downstairs windows 6%
Ceiling to upstairs 3%

Roof 6%
Upstairs solid wall 18%
Upstairs cavity wall 2%
Upstairs windows 6%

Increase the loft insulation to 350-400mm and do the calcs again.

OK.
Thermal conductivity of mineral wool = 0.038

1/0.5 + (0.3/0.038) = 2 + 7.9 = 9.9.

U val = 1/9.9 ~ 0.10

Losses through ceiling reduced to 70 * 0.10 * 21 = 147W

U value of mineral wool of 100mm is 0.36 according to the British
Standard, Neil, so I think you are probably better off than you think
with respect to the roof, and the difference is not as substantial as
this suggests. I reckoned that this would save about 2.5%.

So worth it.

ROTFL.

You did? Do you laugh at the Vicar of Dibley too?

No, just at your notion that 2.5% is meaningful when compared to a
context of over 30% for the solid walls.


---

..andy

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