They claim R-4 and are on ebay and home stores for $5 to $9 and up per 4ft x 8ft.panel?
Answer- No. It isn’t illegal to claim a test shows some R value because that is not a claim about the product, but about a test result. The values reported to the government are never this high for such thin materials, especially Aluminum which has 200 times the thermal conductivity of ceramics. They simply trap air. That is why they are almost always attached to inexpensive open cell thin foams for vertical uses. The combination dampens the peak heat spots and fills in the cold spots. When less variation is present, there is less heat lost in a building. From THAT point of view they do work, but the point is that the claims made by the manufacturer do not mean what the home owner may think that they mean, and that is poor quality assurance.
