R-Value — A Misleading Measure of Energy Efficiency

Insulation is a really important part of constructing a comfortable home, and that insulation is rated, evaluated, and regulated by this deceptive little number called R-value. Used to commercially rate insulation, the R-value was adopted by the Federal Trade Commission (FTC) to protect consumers against unfair, deceptive, or misleading sales claims.

The R-value information for home insulation products has to be displayed on many types of marketing materials, and at the point of sale, in the hope that disclosure will prevent consumers from being misled by false statements about insulation efficiency.

But, this rating is out of date and doesn’t work very well. Let’s discuss the reasons it’s not an effective measurement.

R-value: A Metaphor

We’re at a social or business gathering, and I hand you a paper Dixie Cup.

While you’re holding it, I pour it full of piping hot coffee.

You shout in pain because it’s REALLY hot, so I give you another cup to put the first cup in, which provides more material between your hand and the piping hot coffee.

It’s still too hot, so I give you another cup, and then another, before it’s finally comfortable enough to hold. Or, I could just have given you a styrofoam cup to begin with, right?

The 4 stacked paper cups work on the same principle as conventional spun fiberglass batt insulation, which depends on thick layers of a rather inefficient and inferior material to stop heat transmission.

The styrofoam cup, on the other hand, relies far less on how much material is present, and instead utilizes a more effective and efficient substance — it remains a single, thinner layer.

R-value: A Bad Calculation

R-value is based almost entirely on thickness (basically the total thickness of the wall assumed to be filled with fiberglass insulation), just like the paper cups.

R-value will always assume that thicker is better.

Put another way, more spun fiberglass material, regardless of its poor efficiency, will always receive an up-skewed rating over a thinner, more efficient, superior material like foam insulation.

This rating is even more meaningless because the calculation is done in a laboratory without considering several real-world factors:

  • Deterioration of insulation over time
  • Air leaks or air flow
  • Humidity or water vapor created inside the building

In short, R-value assumes all materials are created equal, so thickness is what counts.

Neither of those statements are accurate.

The Building Codes

Unfortunately, the commissions that write most building regulations are still using R-value — there are code bodies mandating R-values of 20s, 30s, or even 40s.

As a professional in the construction industry, I can assure you this is ridiculous.

Luckily, much of the residential housing market has embraced the reality that there are better options than fiberglass batt insulation, and we are held accountable to a slightly different set of regulations.

I think it’s really important for our clients to understand the futility of the R-value as well. Many clients are still comparing outdated and meaningless figures that don’t account for the efficiency and quality of the materials available in today’s market.

Other Options — Advantages of Foam Insulation

Foam insulation is superior, even though the R-value will show it’s the same or even inferior.

Another reason SPF (spray polyurethane foam) is one superior option is because it fills all the seams, crevices, and joints as well as the area around braces and fixtures to form an airtight seal.

This eliminates one of the major drawbacks of batt insulation — air can be forced through spun fiberglass. Batt insulation becomes even more susceptible to loss of heat or cool air when it is compressed by wiring, or when it is damp.

But, air does not pass through spray foam insulation.

In a wall or ceiling, there is also the chance that batt insulation might be poorly installed, leaving unprotected gaps. That small fault allows air to pass through with little to stop it.

A 20-mile-per-hour wind reduces heat retention significantly. And when it’s damp from humidity and rain, the effect is worse.

Being nearly airtight and moisture resistant, SPF eliminates those problems.

Some other advantages to foam insulation are as follows:

  • Cleaner — dirt, dust, allergens and contaminants stay outside
  • More comfortable – unlike air passing through a seam and then through the batt insulation, conditioned air can’t escape; no drafts
  • Fresher — fumes and smells don’t permeate insulated walls or affect adjacent spaces
  • Quieter — foam insulation has soundproofing qualities; enjoy quieter interiors
  • More durable — no sagging, settling or potentially irritating airborne particles

In other words, there are a lot of reasons the custom home building industry is leaning heavily towards foam, regardless of what the silly label says about R-value — and our clients’ satisfaction backs up that claim.

Learn More About Edge Crew

We don’t stick to the conventional if there’s something truly better out there.

At Edge Crew, we believe in bringing you all the options available, and we have the means to incorporate new techniques, new technology, and new materials into your truly original dream home.

If you’re going to invest in something unique, we want to help you get the very best. Click the button below and let’s start talking!

There’s no need to hang on to conventions like R-value for convention’s sake.