top side. Many factors like dust particle size, dust composition and the amount of ventilation in the attic affect how dust accumulates and thus the ultimate performance of radiant barrier in the attic. A study by the Tennessee Valley Authorityhttps://www.aivc.org/sites/default/files/airbase 4716.pdf mechanically applied a small amount of dust over a radiant barrier and found no significant effect when testing for performance. However, TVA referenced a previous study which stated that it was possible for the radiant barrier to collect so much dust that its reflectivity could be decreased by nearly half. It is not true that a double-sided radiant barrier on the attic floor is immune to the dust concern. The TVA study also tested a double-sided radiant barrier with black plastic draped on top to simulate heavy dust accumulation, as well as a single-sided radiant barrier with heavy kraft paper on the top. The test indicated that the radiant barrier was not performing, and the small air spaces created between the peaks of the insulation were not sufficient to block radiant heat. Walls Radiant barrier may be used as a vented skin around the exterior of a wall. Furring strips are applied to the sheathing to create a vented air space between the radiant barrier and the siding, and vents are used at the top and bottom to allow convective heat to rise naturally to the attic. If brick is being used on the exterior, then a vented air space may already be present, and furring strips are not necessary. Wrapping a house with radiant barrier can result in a 10% to 20% reduction in the tonnage air conditioning system requirement, and save both energy and construction costs. Floors Reflective foil, bubble foil insulations, and radiant barriers are noted for their ability to reflect unwanted solar radiation in hot climates, when applied properly. Reflective foils are fabricated from aluminum foils with a variety of backings such as roofing paper, craft paper, plastic film, polyethylene bubbles, or cardboard. Reflective bubble foil is basically a plastic bubble wrap sheet with a reflective foil layer and belongs to a class of insulation products known as radiant foils. Reflective bubble/foil insulations are primarily radiant barriers, and reflective insulation systems work by reducing radiant heat gain. To be effective, the reflective surface must face an air space, also dust accumulation on the reflective surface will reduce its reflective capability. The radiant barrier should be