Calculating R-Value the Dummy Way

Insulation marked with its R-Value

As our research staff here at the Antisocial Network ply the currents of the internet in search of people more interested in cash than accuracy, time and again they return to eHow.com. It's just so easy to find bullshit there, they tell us at the annual reviews... Well, they're back again, with another "how-to" article written by someone who not only gets the answer wrong, she also gets the question wrong! and this from a librarian, one of the people who used to be the best places to get information. Our hearts are saddened... whatever: she's Heather Lindsay, a first-timer here at the DotD awards, who took a break from her ongoing obsession with potassium (what's that all about, Heather?) to pen an eHow post called "How to Calculate R-Value."¹ And boy, did she get things wrong!

To be fair, she started out more or less OK, telling readers that

"R-value is an experimentally determined measurement that gives an indication as to the heat loss that can be anticipated through a material..."

...though she managed to expose her scientific ignorance with her next sentence,

"R-value is traditionally represented in either SI, International System of Units, or United States customary system magnitudes..."

We aren't sure whether that second sentence is just clumsy wording or what... However, the "steps" that came next were what suggested to us that Lindsay was outside her intellectual comfort zone, but we already suspected that was the case.

In the first place, only a few people studying thermodynamics and heat transfer are particularly interested in how a theoretical R-value is calculated (or perhaps they're scientifically curious, in which case, more power to 'em). No, most people want to know how to calculate the R-value of their walls, roof, or ceiling -- not of a sheet of plywood. But Heather forges ahead with the latter, making a mishmash of the information in the process. Oh, she gets the calculation process more or less correct: interested readers can check her work against an authoritative source (as opposed to eHow), although Lindsay did do a pretty sloppy job: her instructions are to

1. Measure the temperature on both sides of the material
2. Multiply the temperature difference by the area of the test material
3. Multiply the result from 2 by the duration of the test
4. Divide the result from 3 by the BTUs of heat lost through the material

Her unfamiliarity with the scientific method and experimentation is readily apparent, mainly because she fails to discuss units of measure as well as dropping "BTUs of heat lost" into the calculation from out of thin air. Oh, and it's not "heat lost," Heather, it's "heat loss."

Whatever... in reality, since we have people on staff who know something about insulation, we realized that the OQ was very unlikely to have been about how a theoretical R-Value might be calculated; but was far more likely to have been about how to calculate the increase in R-Value from insulation. There are lots and lots of R-Value calculators on the internet if you're interested. If you're still confused, you probably have people like our Dumbass of the Day to thank for that.

¹ The original has been deleted by Leaf Group, but can still be accessed using the Wayback machine at archive.org. Its URL was    ehow.com/how_8138104_calculate-rvalue.html

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