Insulation/membrane for shed...?

[Gritineye]

I've had one of these on the wall behind my lathe in my completely insulated and sealed wooden shed for years (it was much cheaper back then) I leave it on 24/7 when it's cold out.

https://www.tlc-direct.co.uk/Products/JVSH260PRO.html

Got a freebee dehumidifier and a pound shop humidity gauge in there too, I run it occasionally if the gauge shows high, but never had any problem with condensation at all.

 

[500e]

https://www.ebay.co.uk/itm/Electric...eenhouse-with-Mounting-Brackets-/172244490474
Used to be popular with churches at one time fitted what seemed miles to a 16year old prentice under the Pew's, they were brown though & always in the depth of winter, laying on your back on cold stone floors, your dinner soup frozen in the thermos! shall I go on

 

[Henrik]

Regarding oil vs air, I can't see how it would make any difference to the amount of energy used to heat to a certain temp.

At the end of the day, to heat a space to a set temp, you have to add a certain amount of energy to it (temp being proportional to the amount of energy), so oil vs air vs water is irrelevant from that point of view.

Oil filled don't get as hot in my experience, as in you don't burn yourself if you accidentally touch them, which could be a benefit.