Most experts say that an open wood burning fireplace is only 10-15% efficient. You can improve that by using tempered glass doors, replacing the damper, and adding a few more energy efficiency products. A better solution is to consider an insert which manages all of the for you and provide up to 78% overall heating efficiency. we have inserts which can give you a heating capacity of up to 2,500 square feet. At the same time these inserts will help to increase your burn time on your wood logs.