In uk.d-i-y Mark T.B. Carroll wrote:
The Natural Philosopher writes:

[ plenty of interesting stuff ]

I was wondering, is there any real value to these powdered paint
additives that are sold as imbuing the paint with insulating properties?

Certainly - if you put on 10cm thick of it.

FWIW with windows I'm wondering how regular heavy curtains compare to
these honeycomb shades and blinds with the air cells in them that sit
actually in the frame.