They're very hardy, they just complain more. Your goat should have access to the outside, and a place to stay warm/dry/draft free. If possible, leave it up to her if she wants to go inside or stay out. Her barn should be well ventilated and thickly bedded. She should be safe from predators, especially at night. Her diet should be high in roughage to make cud - rumen action keeps them warm, and high in protein to keep her healthy.