In recent years there has been a great increase in the use of double drape arrangements, particularly in hotels and motels. Such arrangements are also used extensively in offices in commercial buildings and in apartments and private residences. Since this type of shading is not presently covered in the ASHRAE Guide or Handbook, same analysis of the arrangement shpuld be made with a view to include significant information in future issues.

The common arrangement now in use is a heavy opaque roomside drape, usually boxed at the top and extending to the floor; and in some cases overlapping a considerable area of the wall. Often these drapes are lined, usually with a light colored reflective material. Same are sprayed with a coating on the windowside, and same have a thin layer of insulation. The inner drape, between the roomside drape and the window, is usually open weave to admit light, and light colored to increase reflectance; however, there is a wide variety of types used.

This paper studies the relative effectiveness of single vs double drapearrangements for solar heat control.