It's Gettin' Hot in Here...

Guests who tour Home Innovation Research Labs are impressed with our sizeable Hot Box. Indeed, we have one of the largest in the country. Less brawny, but equally titillating, are our four heat flow meters. This equipment is essential to measure the thermal efficiency of insulation (and a variety of other building products), commonly measured by R-value, a measure of resistance to heat flow. And increasingly, as Professional Builder magazine recently noted, energy efficiency is table stakes for the new market.

Who Cares About Thermal Efficiency?

Insulation manufacturers such as CertainTeed, Johns Manville, Knauf, and Owens Corning, all seek independent, third-party verification of the R-value of their products and test their insulation products in Home Innovation’s state-of-the-art lab facility. Our heat flow meters are used to run ASTM C-518 Standard Test Method for Steady-State Thermal Transmission Properties by Means of the Heat Flow Meter Apparatus. The result of this testing is the R-value of insulation material (or any other material requiring determination of its thermal conductivity properties). The higher the R-value, the better the insulation—and the more energy and dollars homeowners will save using it.

A heat flow meter works by placing the insulation sample between two metal plates: one hot and one cold. The distance between the plates is adjusted based on the insulation thickness. A meter in the apparatus measures the amount of heat flowing from the hot plate to the cold plate. If I know the temperature difference between hot and cold, the distance between the two, and the amount of heat flowing, I can calculate the insulation’s R-value.

Don’t Run Afoul of the R-Value Rule

Accurate R-value measurements are important not only to ensure an insulation manufacturer’s credibility, but also to keep them from running afoul of the Federal Trade Commission (FTC). The FTC enforces Rule 460, otherwise known as the “R-value Rule,” to protect consumers against deceptive and unsubstantiated claims about an insulation product’s resistance to heat flow. And the stakes are high for getting it wrong. Just last year the FTC won a $350,000 settlement in federal court against a home insulation marketer for advertising that included false claims. FTC’s Rule 460 cites ASTM C518 as one of the test methods acceptable for determining R-value.

Home Innovation has two types of heat flow meter devices to allow us to test a variety of insulation types with great precision. One measures heat flow in the vertical direction and one measures it in a horizontal direction. For most materials the direction is not a significant concern. However, for some materials, such as loose fill mineral wool, the test specimen must be kept horizontal to keep it from spilling out of the equipment. Another important factor is the size of both the test specimen and the metered area. The heat flow meter apparatus is based on the assumption that heat flow is one-dimensional, in other words that heat only flows straight through the insulation and not sideways. In reality, there is always a tendency for some heat to go sideways. Thus, the test specimen used is always larger than the area where the heat flow is measured. This area is referred to as the “metered area” and is centered in the test specimen. Using a larger specimen than the metered area tends to make the heat flow through the metered area one-dimensional. Home Innovation’s heat flow meters can work with specimens as large as 24" x 24" or as small as 16" x 16".

Think IN the Box

Home Innovation most commonly tests building insulation (e.g. fiberglass, cellulose, rigid foam, etc.). However, we can also test a variety of other building materials including wood products, composite blankets, duct materials, and composite systems. Many manufacturers and builders are in need of thermal testing for more complicated specimens, such as an entire wall assembly. Those tests are conducted in our state-of-the-art Hot Box. Are you interested in measuring insulation value or thermal conductivity properties? If so, I would love to design the testing protocol that would best suit your product’s needs and budget. Please don’t hesitate to contact me for a custom proposal.

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