The Kume is a roll-up curtain that is composed of four distinct layers.
- A front panel which acts as the first layer and seals the perimeter of the window opening when the curtain is closed
- A moisture barrier which prevents indoor humidity from reaching the window and condensing on the cold glass and window frame
- Wooden battens which maintain the fabric stretched out and thereby ensure that the curtain fits tightly against both sides of the window opening (the battens also create air pockets which further reduce heat losses through the curtain)
- A back panel which acts as the final layer of insulation and helps seal the perimeter of the window opening when the curtain is closed.
- Still air is one of the best insulators found in nature, and the Kume curtain contains a lot of it. First, between the fibers of the thick polar fleece that is used to make the curtain, and second inside the thin spaces that are created between the front and back panels by the battens.
- When closed, the Kume curtain fits tightly against the top, bottom and sides of the window opening. By doing so it traps a layer of insulating air between the glass and the curtain, and prevents the cold air that forms against the glass from seeping into the room.
- A Kume curtain basically works just like a good down jacket on a cold winter day. The air that is trapped in the thick layer of down creates an effective insulating layer, and the tight fit of the jacket around your waist, neck and wrists keeps your body heat in, rather than letting it leak out into the cold environment.