It wasn't that cold here in April and it killed us. I do have to say that our local Lib paper has been crying about fuel oil prices since spring. However, they are pushing for people to get wood burners and outside furnaces. I'd never heard of an outside furnace before.
I'm no Greenie, but that seems environmentally insane.
Outdoor wood furnaces are fantastic if you’ve got a place to cut the wood to feed them. We installed a WoodMaster 4400 when we built our new home last year. It heats both the house and my workshop. All the mess, bugs and stink stay outside. Love it.
http://www.woodmaster.com/products-woodmaster-4400.php