Just had an area of glazing installed (approx 20 sq.m in big panes) Centrepane u 1.2. Hybrid frames with a thermal break in the glass carrier.

My spec. called for warm-edge spacers. They have installed silver. Should I:
1. Ask for them to be all replaced knowing the last units they mis-measured went in the skip (& presumably to landfill)? or
2. Ask for a discount based on my increased energy use over the next 10 years? or
3. Any other ideas?

Is there an easy known method of calculating the increased heatloss?
Also a little frustrated that the spacers dont match those in the replacement windows (Russell Timbertech in grey with grey warm edge spacers which look very nice.) Black spacers would have been my second choice FWIW.

Any thoughts?

+1 for Tony's opinion. You have not got what you spec'd, but you are doing them a favour. My understanding is that 4/16/4 Low E soft-coat, argon and w/e spacers, in a timber frame, just manages U(w) of 1.6. I doubt you'll be a great deal off that.
I suspect that if you can calc the extra heat loss, the amount might come to less than the discount I'd like! But I may be wrong!

Thanks for your input. You've confirmed my thoughts wrt discount!

Even with discount I'll still be disappointed if we get significant condenasation at the glass perimeters.

If I understand correctly, 'whole window' u values are based on a 1sq.m window. The 1.2 u is the manufacturers quoted centrepane value. The real world whole window u should be significantly better then 1.6 due to the large panes (low ratio of perimeter to area) but the warm edge spacers were supposed to help further with this. The hybrid frames have a thermal break in the glass carrier which is now rather pointless! I'm pretty sure they are metal spacers rather than silver foil faced but I will check further.