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If We Rated Cars Like Air Filters

August 03, 2018 |

cylinderASHRAE 52.2 gave us the Minimum Efficiency Reporting Value (MERV) for air filters, creating a 16-point chart that tells us what percentage of particles in a certain size range will be removed by a filter.  This system was an improvement when it was introduced in 1999 but the past twenty years has exposed some serious flaws with the MERV air filter rating/testing system.  This can be illustrated if we used the same methodology to assign fuel efficiency standards to cars.

Taking the MERV methodology to cars we would need to create a new term that sounds impressive, but is difficult to remember, like “Minimum Fuel Efficiency Reporting Value.”  Now, because we are going to test all vehicles, from diesel tractors to hybrid-electrics, using M-FERV we need to create a robust numbering system – say 1-16.

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After that challenge is completed we need to separate the Miles-Per-Gallon efficiency into three different test parameters.  Vehicle speed is probably best because we drive cars at a variety of speeds so well create three ranges S1, S2, and S3.  Testing will be done to determine the MPG a vehicle gets when it travels within a range of speeds.  Those speeds would be S3/Slow 0-3MPH, S2/Moderate 3-10MPH, and S3/Cruising 10-70MPH.

(Is this making any sense, or does it seem too complicated yet?  All we want to know is how far we can go on a gallon of gas right?)

Then we’ll pick efficiency benchmarks based on a cars performance in these different ranges and then assign a value of 1 (least efficient) to 16 (most efficient) to make it “easier” for the consumer to know what they are getting.  Here’s what the chart would look like:

MFERV

Now that’s been produced, we’ll leave it up to the automotive industry to test their vehicles themselves and promote their product however they feel is best.  So if one manufacturer wants to say their cars get 70 MPG because that’s what their tests show they can – with no oversight from a regulatory body.  

Manufacturer’s can also promote how their car has a M-FERV of 12 and that is far superior to the competition’s car that’s a M-FERV of 9 all the while failing to mention that 99% of your driving is done at 10-70MPH and there is only a 3MPG difference between the two ratings.

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Going the other way a manufacturer could argue that a car with a M-FERV 12 is nearly as good as a car with M-FERV 13 because their only 1 number apart on the rating scale, never mind that the 13 is more than 3-times more efficient in the most crucial S1 range.

Clear as Mud? 

That’s the state of air filter ratings in the United States, almost seemingly designed to be deceptive.  The good news is there is a much better standard that’s been adopted worldwide outside the US called ISO 16890 that hopefully someday we’ll be using here.

Tags: MERV ISO 16890 Energy Efficiency IAQ HVAC

Written by Ben Klawitter