Energy Saving Reflective Insulation Technology: Reflective insulation and radiant barriers have earned their “metal”

by Jonathan McGaha | February 27, 2013 12:00 am

Energy efficiency in metal construction is an important design consideration for architects and metal builders. Energy saving reflective insulation technology, which was first developed in the 1920s to block radiant heat gain, has matured for various building applications, including commercial, industrial and agricultural buildings. Reflective insulation improves operating costs and comfort levels for those who own, occupy or store inventory in metal structures.

Reflective Insulation and Radiant Barriers

A polished film of aluminum is the primary component of reflective insulation and radiant barrier insulation systems. Compared to a dark surface, aluminum only emits 3 to 5 percent of as much radiant energy from its surface. Thus, reflective insulation and radiant barriers can block 95 to 97 percent of radiant heat flow.

There are several types of reflective insulation and radiant barrier systems for metal buildings: that are draped over the purlins, or attached to the underside of the purlins, the highest performing application.

Some spray-applied coatings for metal roofs, known as Interior Radiation Control Coatings (IRCC), are not technically reflective insulation or radiant barriers. The standard specification for reflective insulation is ASTM C1224. For a product to be a radiant barrier it must meet the requirements of ASTM C1313, the standard specification for radiant barriers. The aluminum surface must have an emittance of 0.10 or less and a reflectivity of 90 percent or greater. IRCCs typically have a range of emittance levels from 0.19 and 0.25, which is far greater than that of a reflective insulation and radiant barriers. The lower the emittance values the better in terms of thermal radiation.

New Construction and Retrofits

In new construction, a multipurpose reflective insulation for use in pre-engineered metal buildings is the typical product specified. This insulation is available in single bubble and double bubble with two options of facings: metalized aluminum on both sides or metalized aluminum on one side and white polyethylene on the other.

These insulations can be easily cut to go around obstructions and penetrations. An integrated tape tab, which eliminates taping systems, ensures ease and correct installation. These insulations also help serve as an excellent insulated vapor barrier.

When the reflective insulation is draped over purloins with a 1-inch airspace, the aluminum faced product can achieve an R-value of 10 and the white facing insulation can achieve an R-value of 6, according to published information from leading manufacturers. If the white poly is left exposed for a white ceiling, the reflectivity of the ceiling can help reduce energy costs for lighting. To gain additional thermal performance, the product can be applied on the bottom of the purlins, which increases the air enclosed space and therefore the thermal performance. This application also covers the purlins, which reduces the likelihood of condensation or the purlins sweating, and also allows for backfilling with mass insulation for meeting greater thermal performance requirements.

Overall, reflective insulation technology is easy to work with and is effective working alone or in combination with other insulation products to reach the desired energy performance, including LEED’s ASHRAE 90.1-2007 requirements in the 2009 version of the green building rating system’s Energy & Atmosphere Prerequisite 1: Minimum Energy Performance and Credit 1: Optimized Energy Performance.

Reflective insulation systems include recycled content for LEED Materials & Resources credits. They also assist project teams indirectly with Indoor Environmental Quality credits addressing thermal comfort. With greater control of the thermal performance inside a building, metal building owners will have more options for leasing or the items that can be placed in the interior space including not just people but also livestock or non-perishable food warehousing.

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Bill Lippy is senior vice president and chief marketing officer for Fi-Foil Co. Inc., Auburndale, Fla., and has more than 20 years experience in energy efficiency and solar energy industries. Fi-Foil manufactures and distributes a complete line of reflective insulation and radiant barriers for residential, commercial and agricultural applications.

Paul Nutcher, CSI CDT, is the president of Green Apple Group LLC, a marketing and sustainability consulting firm for building product manufacturers based in Winter Park, Fla.

To learn more about Reflective Insulation Manufacturers Association International, visit www.rimainternational.org[1].

Source URL: https://www.metalarchitecture.com/articles/energy-saving-reflective-insulation-technology/

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