Tubular heaters are very good for sheds, playhouses, kennels etc, if you can get an electricity supply to the accommodation. I have one in each of my kennels and also my playhouse. They give out a very gentle heat so don't make it really warm inside, but just take the chill off. They have made a real difference and have taken a lot of the worry away. Water bowls don't freeze either.
Vetbed is a nice covering to have on the floor in winter, it's lovely and cosy. Poppy and Pansy have vetbed in their kennel. The rest of my bunch can't have it unfortunately as they dig and destroy it. :roll:
I change litter/hay trays daily anyway, but I am even more fussy in winter and will sometimes do twice a day if necessary as I don't like any dampness in their accommodation when it's cold, particularly at night. I use megazorb as it is very absorbent and this is covered with a thick layer of hay.
For my healthy bunnies, they have access to their runs when it's cold (which have a roof and are only meshed at the front anyway). Unfortunately my conti Bentley has mild arthritis, so on cold nights he and Minnie get locked in their playhouse.
My trio have a little 'hayloft' which is a nice place for them to snuggle up. A lot of cold comes up from the ground, so if your accommodation is at ground level, it's good to give them somewhere higher up to go.
I've also got wooden hidey boxes which are all closed in except for the little access hole. I put loads of hay/straw in them and it makes a cosy place for them to snuggle up. Poppy & Pansy have got completely the wrong idea, they use their cosy den as a toilet. :roll: