"Keeping Your Dog Outside

1.13 Outside housing should consist
of separate sleeping and activity areas.
There should be protection from adverse and
extreme weather conditions including heat,
cold and damp. The sleeping area should be
large enough for your dog to lie comfortably
both in and beside its bed and it should contain
clean comfortable bedding. Insulation and
temperature control in the sleeping area should
aim to keep the ambient temperature between
10°C and 26°C."

Government Code's of Practice for animal welfare are usually the bare minimum for staying within the law.  Many dogs are not even provided with this much.