In article , Imm wrote:
Insulate the loft heavily and heat loss in these rooms reduces
considerably,
^^^^^^^^^^^^

The word you are thinking of is slightly. As has been repeatedly
pointed out, we are currently insulating to levels where providing
any more has a minimal effect.

On the typical 108m2 2-storey house file we supply with our
SuperHeat program the structural heat loss with a roof UV of 0.18
is 111.92W/K which would fall to 105.15 if you could get the
U-value down to 0.05. But at this point with a condensing boiler
the energy split is roughly 33% fabric, 17% ventilation, 33% DHW
and 17% system losses, and the cash saving shown on the SAP
worksheet is £5.78p.a. Most people would rather have a usable loft.

--
Tony Bryer SDA UK 'Software to build on' http://www.sda.co.uk
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http://www.sda.co.uk/qsedbuk.htm