Outdoor rabbits inside

I have two rexes that live outside in there hutch/run combo. I regularly bring them inside for a run in the evening for there evening feed. My question is how long is too long for them to wander round inside as i'm worried it'll affect there tolerance for the cold outside. I generally get them out for about 90 mins in here but is more OK or should i let them run around outside whatever the weather (which is generally rainy living here in cumbria).

Any advice would be appreaciated

Thanks

Jem

Theres a thread about this already

http://forums.rabbitrehome.org.uk/viewtopic.php?t=33400