When I worked in a centre, if we lost heat or electricity,it was called a "serious occurence" and we would close as soon as we could. The Ministry had to be notified as well, so it was serious. We did not refund parents for early closures that were beyond our control. If you can't find a way to cook for the children, or keep the heat at the minimum Day Nurseries Act temperature, then I would close. Just make sure your parents can pickup quickly part way through the day if necessary,(if you open and it goes out part way through the day).