Double gazed with eventually inbuilt/flush exterior shutters or triple?

[CalvinHobbes]

Hello,on a tight budget but trying to get to passivehaus standard. Double glazing seems to fail after 10 years and triple is twice the price. Thinking about external inbuilt shutters to prolong life , can we do it so we can add them at a later date to normal windows easily? Is there a special lintel? Local family company does optima 22 range. Any opinions very welcome.

Edited September 15, 2021 by CalvinHobbes
mistake

[IanR]

3G shouldn't be double the price of 2G, if all else is equal.

I'd recommend 3G, if aspiring to PH levels of energy loss, ideally with triple air seals to assist in air tightness.  Alu-clad will help the durability of the frames (giving a 60 - 80 year life), and certainly shouldn't be failing after 10 years.