Radiant barrier works on two basic properties and it includes reflectivity and emissivity. aluminum being reflective on the hot side it reflects some of the heat back from where it came. Subsequently and most significantly aluminum has a low emissivity, approximately 3% of the heat is emitted to the air on the cold side.it will be particularly efficient in both summer and winter.
Better bought than built. A tight cap for pull-down attic stairs is hard to build. The weatherstripping details can be tough to execute, and the necessary weight of the hatch can be difficult to achieve. The Energy Guardian, shown here, costs about $185 plus shipping. ESS Energy Products (essnrg.com) also makes kits for kneewall access, walk-up stairways, and more.