The REAL WORLD ICF PERFORMANCE and significant energy savings experienced each month have been demonstrated by satisfied home and building owners for decades.

We decided to take an objective scientific look at the real difference between ICF walls and the traditional wood framed cavity walls used in the majority of the US. This first test looked at walls that are code compliant for Climate Zones 1-5. Future studies will compare other types of walls systems and insulation.

In 2016 the ICF Manufacturers Association commissioned an independent scientific study comparing a wood-framed cavity wall to a standard 6-inch core ICF wall.

Why do ICFs work so well?

ICF thermal mass

Insulating Concrete Forms sandwich a solid reinforced concrete core between two 2.5″ thick panels of dense EPS foam. This foam is extremely good insulation and delivers unparalleled energy efficiency. Why?

The exterior temperature is stopped from influencing the inside temperature through both the EPS foam insulation and the concrete core. While the EPS foam works as effective insulation it’s the thermal inertia of the concrete core that adds the greatest advantage. The concrete is heavy and dense and resists changing temperature. Once heated, concrete stays warm for a long time. The opposite (cold concrete) is true as well.  This thermal inertia of concrete helps stabilize the wall temperature. Combined with the insulation on both sides of the wall create a superior thermal barrier. This prevents both exterior and interior temperature changes from affecting the wall temperature on the other side.

See ICFs in action & learn more about building with icfs!

Real World ICF Thermal Performance Independently Proven

icf thermal inertia

The study was surprisingly revealing; confirming dramatically superior energy-efficiency performance and an overall better R/RSI-value being achieved by the ICF Wall assembly.

For decades, the ICF Industry has been asked to provide definitive proof that thermal mass, the airtightness and continuous insulation features of ICF walls deliver real, quantifiable benefits in terms of overall energy-savings and achieved R/RSI-values. Many studies have been conducted in the past by the Portland Cement Association (PCA), the Canada Mortgage and Housing Corporation (CMHC) and the Department of Housing and Urban Development (HUD). However, all of which were either based on limited field comparisons or thermographic computer modeling. This is the first time an SCC and ISO accredited and an internationally recognized testing facility has been commissioned to evaluate a realistic side-by-side comparison of these two types of wall assemblies within a single study. The reported results confirm the following when building with ICFs:

  • 58% better overall R/RSI-value than the insulated wood frame cavity wall
  • 60% better energy savings than the insulated wood frame cavity wall
  • Measurable effect directly attributable to thermal mass & continuous insulation on both sides of the wall assembly
  • The 2″x6″ wood framed cavity wall required 38.9 kWh to maintain steady state. The ICF wall only required 15.6 kWh of energy to do the same work.
  • This is a consumption of 132,828 BTU for the wood-framed cavity wall versus only 53,209 BTU for the ICF wall.

The CLEB Study tested the conditions of the walls under “steady state.” What does that mean?

Steady State

  1. Physics – A stable condition that does not change over time or in which change in one direction is continually balanced by change in another.

Source: American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved. 

“Steady  State” means that the amount of heat required to be delivered to the interior side of the test wall to maintain the interior space at a constant temperature of 70°F (22°C) is exactly consistent with the rate of heat flow that is transmitting through the wall (due to ITS exterior condition being maintained at -31°F (-35°C).

ICFs by the Numbers

ICFs performance statistics

What does this mean for consumers?

The results are clear! ICF thermal insulation performance is unmatched! Building with insulated concrete forms is the proven way to build a home or building. Build with ICFs for better energy-efficiency and far greater R/RSI-value benefits than traditionally insulated wood frame walls. Make your choice today and enjoy savings for a lifetime.

For more information about BuildBlock Insulating Concrete Forms, visit our Common ICF Myths & Misconceptions page.

Seeing is believing!

Below you will find a copy of the report completed by CLEB Laboratories for the ICFMA with more information. A PDF of this report can also be found online at

For more questions about this study or actual BuildBlock ICF performance, connect with us in person at +1-866-222-2575 or [email protected]


To see more downloadable publications from BuildBlock for educational publication, product specific publications, product installation manuals and ICF installation & engineering publications, visit the Publications page.


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