This standard establishes the characteristics that must be met by materials, products, components and thermal insulation elements for ceilings, drop ceilings and walls of buildings. The properties of the materials under this standard are: apparent density, thermal conductivity, water vapor permeability and moisture adsorption. In order to determine the characteristics, must be reviewed the test methods specified in the standard. See the attachement for the testing methods specified in the standard.The standard NOM-018-ENER-2011 supersedes the NOM-018-ENER-1997. The 2011 version updates the standard with two new testing methods for "apperent density" parameter.