If you need light then fit them!
My understanding is that the Triple glazing / U < 0.8 rule is a requirement for central European Passiv Haus project, not 'mild' UK!
The primary means of PH compliance is the specific Heat load, not individual heat losses, particularly through windows as these are in a state of flux with more heat gain being possible through different types of windows; Although some consistency (of high standards) is needed.
PH are interested in the point at which this heat flux becomes positive. As an example North facing windows will typically be triple glazed and small, south facing windows may be double glazed, particualrly in the South of England (possibly).
The amount of natuaral daylight available from a roof light is literaly an order of magniture more than a shaded vertical window.
Even a Velux windows, (with an external roller shutter) could be made to work!
As a quick check, I added a 1m2 'UK standard roof light' to a 200m2 PH home, increasing specific heat demand from 12.6 to 12.9, along with a slight increase in overheating risk.
I have seen triple glazed units from a company called 'Fakro'
