Thermal Emittance Evaluation of Coatings for Use as Interior Radiation Control Coatings
Especially formulated coatings and paints are used in building applications to conserve energy. A large number of products called “radiation control coatings (RCC)” are used on exterior surfaces to reduce the amount of solar energy absorbed by the surface and transported to the interior. Another class of products called “Interior Radiation Control Coating Systems (IRCCS)” is available for use on interior surfaces to reduce heat transfer between the interior air and the coated surface. Consensus standards for both product types have been developed by the American Society for Testing and Materials (ASTM). This evaluation was undertaken to determine the suitability of specific paints and coatings for use as IRCCS. The ASTM document for IRCCS (C 1321, “Standard Practice for Installation and Use of Interior Radiation Control Coating Systems in Building Systems”) states that an IRCCS will “normally have a far-infrared emittance of 0.25 or less”. The ASTM standard also identifies the method for measuring the emittance (C 1371, “Test Method for Determination of Emittance of Materials near Room Temperature Using Portable Emissometers”).
The standards organization, ASTM, has identified a class of coating materials, specified the controlling energy conserving property, and identified the method for measuring this property. The energy conserving property is identified as “thermal emittance” in this report. Following the lead provided by the ASTM, 20 products were tested for thermal emittance and classified as an IRCCS if the ASTM standard (thermal emittance less than 0.25) was met. The paints and coatings were applied in accordance with the manufacturer’s instructions and tested in accordance with ASTM C 1371 by an independent laboratory accredited by the U. S. Department of Commerce (NVLAP) for this type of measurement.
The following table contains the thermal emittances that were measured. Each of the thermal emittances in the table is an average of three measurements.
Measured Thermal Emittances for Twenty Coatings
|Heat Bloc 75||STS Coatings, Inc.||0.22||yes|
|Heat Bloc-Ultra||STS Coatings, Inc.||0.195||yes|
|Lo/Mit-1||Solec-Solar Energy Corp||0.23||yes|
|Lo/Mit-2||Solec-Solar Energy Corp||0.17||yes|
|Lo/Mit-II Max||Solec-Solar Energy Corp||0.147||yes|
Revised August 8, 2012
R&D Services, Inc.