Cutting Radiator Heating Costs

This idea (in italics) comes from The Complete Tightwad Gazette by Amy Dacyzyn.

"Here's an energy-conservation idea for those with accordion-style radiators.  Put a foil-faced insulation board between radiators and outside walls, with the foil side facing in toward the room.  This reflects heat into the room that would otherwise radiate through the walls....Because the expense is minimal and the installation is not permanent, this is one of the rare energy-saving ideas that is useful to renters."  (pages 414-415)

Foil insulation comes in various forms, such as rolls for attics, crawl spaces, etc, which may work for this purpose if you can't find a board. You could adhere a piece from the roll to a thin piece of wood or the wall behind the radiator.  Or you could use a staple tab roll that is simply installed using a staple gun and scissors. There is also a type that has hook-and-loop (velcro) type fasteners that is used for shutters, but I think it could be used for this purpose as well. The shuttercover type is about $50, but covers 16 sq feet, so it might be able to be used in other places if you have leftover pieces, such as behind headboards, couches, or curtains on exterior walls where it will not be seen.  There is also a type for insulating exposed duct work.  These are just a few ideas to consider. Any additional insulation is generally beneficial.