On Sun, 14 Mar 2010 16:10:03 +0000 Peter Johnson wrote :
You could consider just changing the glazing for Pilkington K glass
which is more efficient thermally than what you have and which will
cost less than what you have.

May or may not be worth it. Back in the UK my local glazier was
charging a £50/m2 premium for low-E argon units over regular DG,
probably reducing the U-value from about 2.8 to 2.0. I used to reckon
that reducing the U-value by 1 saved £1/m2 on the average house,
possibly £2 now, so that would give a 3.2% return, but that's cancelled
out if you assume a 25-year life for sealed units. If you can get the
low-E glass for a much lower price or energy prices increase
significantly then the economics would be better.

--
Tony Bryer, Greentram: 'Software to build on' Melbourne, Australia
www.superbeam.co.uk www.superbeam.com www.greentram.com