The Truth About R-Value

The labeled R-value found on insulation products is often misleading and does not reflect true insulating performance under real world building conditions.


Lab Tested R-value vs. Real World Thermal Performance

Understanding thermal performance will help you make the best insulation decision. Under controlled laboratory conditions, our Hybrid System has roughly the same tested R-value as fiberglass. R-value measurements are derived from small, meticulously prepared laboratory samples and do not indicate how an insulation system will perform once installed in an actual building. These laboratory tests are performed in a closed box and do not introduce any air movement or convective airflow. The EPA has repeatedly confirmed that this testing method is flawed. For example, fiberglass will experience an R-value drop from R-21 at 75°F to R-12 when tested at 9°F. In contrast, because our seamless system forms an air barrier, it eliminates convection and stops thermal heat loss. As you may have guessed, this means the same thickness of our insulation will have greater thermal performance than fiberglass. Our spray-applied products create their own cellular vacuum, stopping air movement or thermal degrading convective loops penetrating the cavity.


How to Stop Heat Transfer/Loss

In order to understand how our Hybrid insulation system works, and why it is so much more effective than Fiberglass, we must first understand how heat transfer works β€” Conduction and Convection. Conduction is the transfer of heat through solid molecules, making it the slowest method. Convection is the transfer of heat by liquid or gas molecules moving from hot areas to cold areas. This results in a convection current that transfers heat energy from warm areas to cold areas. Heat transfer by convection, as anyone who has felt a winter draft on bare feet can attest, can be rapid and dramatic. It also accounts for 80% of heat loss in a building. Thus, most insulation methods address convection β€” albeit in different ways, and with different results. Fiberglass insulation slows convection, while our system stops it. As exterior temperature drops, convection currents speed up and all fiberglass insulation become less and less effective at slowing these convection currents down. As a result heat loss increases. Our system is designed to stop convection by stopping air infiltration.


Convection Comparisons:

EnergySeal

Our seamless hybrid insulation system forms an air barrier that eliminates convection and stops thermal heat loss in its tracks. Our insulation system has been proven to provide consistent performance at temperatures as low as -40°F. This means that our seamless insulation system maintains its resistance to heat transfer under virtually all weather conditions that occur in North America. Our seamless insulation system works by creating its own cellular vacuum, stopping convection and air movement. Our airbarrier-insulation system combinations are unaffected by wind pressure or climate temperature extremes. It is for these reasons that we can say we offer the most versatile, seamless, air barrier-insulation spray technologies available today.

 

Fiberglass

Convective heat loss makes maintaining R-value at below freezing temperatures a problem for all types of fiberglass. Fiberglass is a porous material that relies on air pockets trapped between minute glass rods to stop heat transfer. The ability for air to move freely through fiberglass is what makes it such an ideal material for furnace filter. Unfortunately, when air moves around so does heat, and this property is the primary reason that fiberglass cannot perform at it’s labeled R-value outside of the laboratory and in real world conditions. At about 32°F, air begins to circulate within the fiberglass. Hot air rises and cold air falls within the fiberglass creating a convective loop that transfers heat from the inside to the outside, greatly undermining the thermal efficiency of the insulation. This loss of thermal performance and R-value becomes magnified the lower the outside temperature drops and also by the smallest compressions and gaps in the fiberglass. These airflows can reduce the real world R-value of fiberglass by more than 50%.


Additional Forms of Heat Transfer

Thermal Conduction: Heat moves through solid materials β€” quickly through good conductors such as metal, more slowly through wood, and very sluggishly through dedicated insulators. Poorly designed systems can cause excess conductive heat loss and potential building performance issues in extreme climates. Structural conduction through truss systems and solid wood rafters often lead to ice dam problems. Dimensional lumber is much more conductive than engineered I-rafters. I-rafters suffer from only 1/3 the conduction of dimensional lumber and are made without old-growth timber, making them not only more efficient but also a much more environmentally responsible choice.

 

Radiation: Heat also moves as infrared radiation. Radiation on a poorly insulated south facing attic wall can be sufficient enough to raise attic temperatures above freezing and accelerate ice damming.

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