Will my 8 month old silkies cope with 2 degrees Celsius over night?

[Lucyajb]

It’s winter in New Zealand and my two dear wee Silkies have never taken to their omlet chicken coop. They prefer to sleep on the ledge outside. And use the Omlet for a very expensive laying box. The ledge they sleep on is covered by a roof and has ply wood on two sides. It has started to become cold overnight (lowest 2 degrees Celsius). No wind or rain, just still and cold.
Should I be putting them in the omlet once they are docile at night and shutting them in? They are 30 weeks old, and I tried doing this when I first moved them outside but they never quite took to it.
Wondering if I should persevere.
Photo of their sleeping situation below

 

[1muttsfan]

Put them inside for the night and shut the door. Once they are used to using the coop they will likely use it regularly. And that is pretty cold for a silkie outside.

I have had young birds that became accustomed to roosting out in the pen, then when the weather turned bad they got wet and cold. And yet still would not go in to roost, until they were shut in at night for several days.