A fireplace is a great tool to use during the cold winter months. It can be used to help set a mood or just to keep you and others warm. But when the fire is out, it's important to close off the entrance to prevent any cold air from coming in and any warm air from leaving. The best, and cheapest, way to do this is by creating a fireplace insert.
This conservation tutorial will show you what you need and how to create a great fireplace insert. Good luck and enjoy!