Click this link to watch a few short videos on energy use in an existing home.
This book will provide you with some ideas of areas where energy can be wasted in an existing home.
Home Energy Use 101
Basement Insulation
Basement walls are often overlooked when it comes to insulating. Considering the number of basements that are built with poured concrete and how easily heat can transfer through even a solid concrete wall, this is an area of concern and potentially significant heat loss costing you money. Watch this video to see what to look for concerning insulation in basements.