Abstract: An insulating device reduces heat transfer through a barrier--such as a wall, window, door, floor, or ceiling of a building--and into an area adjacent to the device. The insulating device includes at least one flexible sheet supported from an area above the section of the barrier to be insulated and is attached at its free end to the barrier above that section. Accordingly, the flexible sheet is doubled back upon itself and forms an insulating air space. A second flexible sheet can be attached to the support and disposed around the exterior of the first flexible sheet and attached to the barrier above the section to be insulated. Where two flexible sheets are doubled back upon themselves in such a manner, three insulating air spaces are provided. Accordingly, the insulating device impedes conductive heat transfer across the device. At least one flexible sheet includes a material having a low emittance to reduce radiant heat transfer across the device.