Building insulation materials weak and brittle. Before its risks were recognized, it was used because it was a cheap, effective insulator with a high R-value and its open-cell structure was a good acoustic insulator. Though it absorbed moisture easily, it regained effectiveness as an insulator when dried. Asbestos once found common use as an insulation material in homes and buildings because it is fireproof, a good thermal and electrical insulator, and resistant to chemical attack and wear. It has been found that asbestos can cause cancer when in friable form (that is, when likely to release fibers into the air - when broken,
Building insulation Aerogel was first discovered by Samuel Stephens Kistle in 1931. It is a kind of gel that the liquid part is replaced by gas, it actually is composed of 99% of air. This material has a relatively high R-value of around R-10 per inch which is considerably higher compared with conventional plastic foam insulation materials. But the difficulties in processing and low productivity limit the development of Aerogels, the cost price of this material still remains at a high level. Only two companies in the United States offer the commercial Aerogel product. In hot conditions, the greatest source of heat