another due to the reflective surface (or low emittance). There are a lot of definitions about “Thermal/Heat Insulation” and the common misinterpretation of “Thermal/Heat Insulation” = “Bulk/Mass/Batt Insulation” which is actually uses to resist Conduction Heat Transfer with certain "R-Value". As such Materials reflecting Radiant Heat with negligible “R-Value” should also be classified as “Thermal/ Heat Insulation”. Thus Reflective Insulation = Radiant Barrier Advantages Very effective in warmer climates No change in thermal performance over time due to compaction, disintegration or moisture absorption Thin sheets takes up less room than bulk insulation Can act as a vapor barriers Non-toxic/non-carcinogenic Will not mold or mildew Radon retarder, will limit radon penetration through the floor Disadvantages Must be combined with other types of insulation in very cold climates May result in an electrical safety hazard where the foil comes into contact with faulty electrical wiring Hazardous and discontinued insulation Certain forms of insulation used in the past are now no longer used because of recognized health risks. Urea-formaldehyde foam (UFFI) and panels Urea-formaldehyde insulation releases poisonous formaldehyde gas, causing indoor air quality problems. The chemical bond between the urea and formaldehyde is weak, resulting in degradation of the foam cells and emission of toxic formaldehyde gas into the home over time. Furthermore, some manufacturers used excess formaldehyde to ensure chemical bonding of all of the urea. Any leftover formaldehyde would escape after the mixing. Most states outlawed it in the early 1980s after dangers to building occupants were discovered. However emissions are highest when the urea-formaldehyde is new and decrease over time, so houses that have had urea-formaldehyde within their walls for years or decades do not require remediation. UFFI provides little mechanical strength, as the material is 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 Asbestos is a mineral fiber that occurs in rock and soil that has traditionally been used as an insulation material in many homes and buildings. It is fireproof, a good thermal and electrical insulator, and resistant to chemical attack and wear. It has also been found that asbestos can cause cancer when in friable form (that is, when likely to release fibers into the air – when broken, jagged,