If you have a good thermal envelope (without holes) your house will remain warmer in any weather so will your thermal mass.
Using 'sinkholes' as if there are absolutes levels of insulation is not helpful. There are just relative amounts of insulation. All parts of the 'thermal envelope' leak heat just at differing rates. In order of greatest to least:
R10 Wall (Superinsulation standard): U 0.1
R3.5 Ceiling: U 0.26
R2.5 Wall: U 0.34
Triple glazed window: U 1.2
Uninsulated wall: 2.22
Uninsulated ceiling: U 2.56
Double glazed window: U 4.2
Single glazed window: U 7
Look where double glazing ranks in this list. How it does it compare to a non-insulated wall let alone an insulated one? Which one is the sinkhole?
Nice try but double glazed windows U 4.2 is complete nonsense
That was maybe in the 1960's when DG was not a sealed unit.
Even the worst DG windows (aluminium with no thermal break) have U 3.7
Our uPVC windows have U 1.8 and better and thermally broken aluminium must be somewhere in between.
Any reasonable good window (DG) has a better U- value than an uninsulated wall.
It make no sense to combine a highly insulated wall with zero insulated windows.
Every component of the thermal envelope has a different rate of heat loss but for every component a minimum level of insulation value is desirable.
A single glazed window means next to zero insulation.