Bay windows are in effect larger then windows which are set in therefore they can be much less efficient then other window types. With windows letting out a lot of heat and a lot of draft in it is important for the windows in your home to be as efficient and cost effective as possible. You will find that if you have draughty windows which are not correctly sealed you will be paying higher heating bill then which you should be paying. Placing a radiator or heater under a bay window can be like throwing money in the bin.
A lot of people which own properties with bay windows often opt for the to be upgraded and replaced. This is not only for aesthetic reasons but also to increase the energy rating of them. Most old properties which have bay windows are most often made of single pane glass which is the worst type of window to have especially in a bay. It can be double your heating bill every month. If you are looking to upgrade your bay windows to something which is more energy efficient there are many companies out there which can create replica windows in a modern day efficiency way.
Modern day bay windows use two or three panes of glass which may contain gas to make the extra energy efficient. By coating the panes of glass in film blocks it can help the transference of the heat and cold from the outside world. Using more then one pane of glass adds an extra barrier so the more panes of glass a window has the more heat it will keep in. Not only the glass can add insulation but also making sure you choose an appropriate material for the window frames. Vinyl is known to be the best insulator but can look ugly and be hard to keep clean.