I decided to to see if a my insulated hives and nucs made a real difference by measuring how much temperature difference bees could make in
a) A wooden hive
b) My foam Nuc.
This is how I did it . I wired up a 12v bulb to variable power supply that would would show volts and current and set up a pair of temperature sensor to show the temperature difference half way up the the hive.
in the wooden hive (a kit bought from a beekeeping supplies company) after 3 hours with 20w the temperature got to 5 degrees C (9f) above ambient. 20 W is about what a winter cluster puts out.
I then tried it with my foam hive with just 10W and in 1 hour I got 20C (36f) above ambient. That means the foam nuc is losing about 1/8th of the wooden hive. In the wooden hive the outside temp only has to fall to close freezing to produce killing temperature inside the hive, where as in the foam nuc even a small colony is good down to minus 15C. Seeing is believing so I took some pictures.
wooden hive the power is 8 x2.4 =19.2W temp difference 5C
the power is 5.3 x 1.9 = 10W temp difference 20C