I assume the reflected heat means they are warmer? If so, I need to get hubby some of these. He's a freeze baby and I hate turning the thermostat above 66.
Technically, they aren't "warmer", but simply prevent you from losing heat from a radiative process.
They would essentially do the same thing as a mylar/"space blanket" but are probably a lot more comfortable/practicable.
Most things people wear to keep warm block heat loss from conduction.
They work the same way as the insulation in your walls/attic. Dead air traps heat.
If hubby get's cold, then there are some other things to do to help him.
For many people, the issue is moisture on their skin. When that evaporates, it sucks beaucoup heat out of the body. That's why we sweat in the heat.
So if you could get him some wicking undergarments that would help.
I'm old enough to have done this before all the new high tech fabrics came out, so I still have silk undergarments for that when I go cross country skiing.
But there are plenty of newer high tech stuff that does the same thing.
After that, think layers. The more trapped air you have the better.
Keep in mind how the body prioritizes heat.
Head #1
Torso #2
Arms and Legs #3
Hands and Feet, dead last.
The body will reduce blood flow in reverse priority, so the hands and feet get reduced first, and so on.
This is why a down vest can keep your arms and legs warm.
If your body core is warm, then the blood flow to the arms and legs won't be reduced.
Sleeping caps may look goofy, but they can make a big difference on how warm you are when you sleep.
