Best outside color for thermal insulation

[freeelectron]

I'm wondering if the outside color has an influence on the thermal depletion of things such as a thermos, a wall, etc.
Assuming, obviously, there's no sunlight hitting on them.
It certainly has, but what difference percentage can we typically expect for example for bottles such as the ones on the image?
Thanks

 

[sophiecentaur]

Shiny silver colour is best, with low absorptivity and, of course, emissivity. It is advantageous in both hot and cold conditions. People tend to ignore the vast amount of energy consumed by your average air con.

There are other considerations in addition to radiation; air flow in and out accounts for a big proportion of the heat loss in most houses so a drastic choice of paint should be matched by sealing all the cracks and around doors and windows.

This ancient link has a list of emissivities of common surfaces (low is good in this application). You will see that the actual colour of paint is not a big factor but that shiny metallic is excellent. Hence the shiny survival sheets for casualties.

The choice of external colour of a water bottle paint is largely aesthetic as the internal insulation does most of the work!