Further to previous posts about calculating radiator sizes, my 17th century
timberframed house has been renovated as far as I can tell by replacing all
the old wall materials with rendered breeze blocks. The walls seem to vary
in width in different places, but the minimum seems to be 9 inches,
presumably solid breeze block. My attempts to google for a u value haven't
been very successful. Can anyone suggest a reasonable u value for this wall
construction that I can use in my calculations?

TIA

Keith