Hutch huggers

I know its not the time of year for them, but with a hutch hugger, how much warmer does it make the hutch?

Mostly Im trying to take my mind off the fact that both my bunnies are in for their neuter/spay finally (took forever to get them to a stable weight) and so I can start to make the space good for a pair rather than having it split all the time. I want to put a hutch in the run in summer as a cooler shelter and in the playhouse in winter as a warmer hut. I just wondered if its worth having a hutch hugger on for warmth in winter and if it makes much difference.

We've got a hutch hugger and the thermal foiled insulating cover too. I'm not sure how much warmer it makes it but the hutch hugger at least keeps the worst of the weather off the hutch.