Replacement dg units, k or not?

[jcp]

The sealed units in my 20-year old wooden window frames have clouded and need replacing.
I did the worst (all those on my south facing wall) maybe 5 years ago using non k-glass units. Should I now use k-glass units on the others?

Relevant factors may be
1. K-glass units cost almost 30% more.
2. In only one room are there units that have been and others that need to be replaced (on different walls), so coatings are unlikely to be visually noticeable.
3. The frames take 4-6-4 units. I vaguely remember once see a table on the benefits of k-glass with different gap widths, but can't find anything now.

Has anyone any advice?

John

 

[crank39]

Not Worth it unless the whole house was K, don't waste your money

1/ Correct
2/ K has a horrible tint to it, could you live with it? Its worth noting that 'K' is a Pilkington product, if you don't want a tint then Saint Gobain do a clear version called 'Planitherm'.
3/ Any benifit from having K will be negated by only having a 6mm air space, definately save your money and just use clear float

 

[squowse]

not much option to get high spec units with that rebate depth, can you increase it?
planitherm is a soft coat and superior to K which is a hard coat.
have a read here as well - http://www.thewindowman.co.uk/misty-wood.htm
and http://www.thewindowman.co.uk/wooden_windows_drainage.htm

 

[^woody^]

I don't think the 30% premium translates into 30% energy saving over the 10 (?) year life of the units