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What is thermal mass? How does the ICF wall make a difference?

Updated: Apr 15, 2021

The solid mass of the Nudura wall has some very unique qualities. The monolithic concrete is layered between two continuous panels of 2 5/8” (67 mm) EPS foam, which isolates the concrete and significantly reduces the flow of heat through the wall.

Since Nudura walls have a high storage capacity with low thermal conductivity, it provides the most useful level of Thermal Mass. This helps to stabilize the internal temperature from day to night temperature fluctuations and provides a largely self-regulating environment. Reducing the amount of mechanical equipment needed for heating and cooling means less energy consumption, resulting in greater cost savings throughout the year.

  1. Less to cool and heat. Buildings with exterior Nudura ICF Concrete Walls, also utilize less energy to heat and cool than similarly insulated buildings with wood or steel frame walls.

  2. Nudura ICF Concrete walls have a high storage capacity with low thermal conductivity, it provides the most useful level of Thermal Mass. This helps to stabilize the internal temperature from day to night temperature fluctuations.

R-VALUE CALCULATIONS OF Nudura Nudura Insulated Concrete Forms have a tested R-Value of 23.59. Click here for more information on Thermal Resistance Calculations.


High Thermal Mass Concrete Core

  • Thermal mass is the ability of a material to absorb and store heat energy. A lot of heat energy is required to change the temperature of high-density materials like concrete. Concrete is said to have a high thermal mass. Lightweight materials such as timber materials have low thermal mass, therefore they do not absorb and store heat energy effectively.

  • When outside temperatures fluctuate, a building with a large thermal mass within the insulated portion can serve to “flatten out” or delay the temperature fluctuations. Nudura ICF’s work in this manner, the concrete core sandwiched between 2 panels of EPS Insulation, effectively improves the building comfort in areas of temperature fluctuation.

Continuous Insulation Layers Inside and Out

  • Nudura provides a complete layer of EPS Insulation on the exterior and interior of your building. With Nudura you will not experience Thermal Bridging as would be found in a stick frame house. Wood components have much higher thermal conductivity than EPS Insulation. Everywhere there is a wood stud, corner post, framed floor or wooden lintel is a location where it is lessened or NO batt insulation. These areas create drafts and cold spots on the wall. An ICF home will not have any cold areas as the insulation is continuous around the whole building.

Superior Air Tightness

  • Nudura creates a much more “airtight” building than any other construction method. Our EPS Insulation acts as an Air Barrier, as proven by accredited ASTM testing. The design of our Interlocks and patented DURALOCK™ technology ensure our blocks are mechanically linked together, thus preventing gaps that could allow air to flow through the assembly. Other ICF companies rely on additional tying of the forms to create this seal, which increases the labor time and money spent.

  • A second feature is the solid concrete core which also acts as an air barrier. The result is an extremely airtight home. A wood-frame house relies solely on an extremely thin sheet of plastic as an air barrier. This barrier is very easily punctured, it has to be joined with a tape product at 9’ increments and it does not self-seal around fastener penetrations. The quality of these wood frame air barriers greatly depends on the method of installation, and the time taken by the installer. It is a much more tedious and time-consuming process than Nudura ICF with less performance.

The combination of these 3 elements together limits the thermal conductance of the finished Nudura wall assembly to a maximum transmission rate of 0.04 BTU/hr∙ft2∙ºF (0.24 W/m2∙ºC)” when tested to -31ºF (-35ºC)


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