The Natural Philosopher wrote:


This is U values not K. Watts per sq meter per degree K.

DG windows range from 2.2 to 4.2..depending on gap, filling and frame.

Hmmm, I hope not... I understood that current building regs requires
windows with U values of less than 2.0 to be installed. Our DG is
apparently approx U=1.2 using Pilkington Optitherm (soft-coated glass),
argon filled and a super-spacer-bar-thingy. The units are called
Pilkington Insulights.

http://tinyurl.com/2rkpv7

Putting all this in a steel/upvc frame might raise the U value to around
1.4-1.5?

J