Probably at some future time needs some more tests done, to determine temperature rise in the new situations for new reference cases.
Or cables to be routed on the indoors side of the wall. 
Or a move to cables with a higher withstand temperature.

Oddly I've just been looking at something using 1.5mm2 railway cables (RL1131 types) and the max core temp of 120C makes for surprisingly high current ratings, almost automotive, so long as routed only in locations that cannot be touched. Just the ends need to be cooled where they terminate onto 'normal' fittings. (given the fun we have with SY I wonder what some folk would make of this ENs but no BS ;-) )

Mike

Probably at some future time needs some more tests done, to determine temperature rise in the new situations for new reference cases.
Or cables to be routed on the indoors side of the wall. 
Or a move to cables with a higher withstand temperature.

Oddly I've just been looking at something using 1.5mm2 railway cables (RL1131 types) and the max core temp of 120C makes for surprisingly high current ratings, almost automotive, so long as routed only in locations that cannot be touched. Just the ends need to be cooled where they terminate onto 'normal' fittings. (given the fun we have with SY I wonder what some folk would make of this ENs but no BS ;-) )

Mike

"Or a move to cables with a higher withstand temperature"

This would seem to becoming a necessity if the current roof void and wall insulation design approaches are sustained and get worse; although how one 'cools' for incompatible accessories will be a challenge. 

Perhaps the way properties are constructed needs a proper review and more thought by building designers to reduce the impacts on wiring and to limit waste as such.  May be the lead and a push should come from the electrical industry.

In one new build I recall, very thermally effective insulation was packed into an internal stud wall and its only purpose was sound dampening ! 

Perhaps Building Regs, where insulation is required/wanted, should mandate that insulation be built into the the materials used for of wall/ceiling, or in cavities, whereby no other is required and cables can be run along surfaces without general issue.

Nothing will be perfect it would seem, but still a little help and from building design would be great especially if specified is 10+ sockets on an insulation packed wall and so on.

:-)