For maximum energy efficiency, EPS rigid foam insulation can be specified to achieve the desired thermal resistance and can significantly reduce air leakage that may occur in roof, wall and below grade assemblies. The amount of insulation required will vary depending on the building design, climate and energy costs, making it important to choose the most cost effective R-value per inch.
EPS delivers R-value ranging from 3.60 to 4.20 per inch. It is the only rigid foam insulation that offers stable thermal resistance from the point of manufacture. Foam insulation is effective in buildings with space limitations and where higher R-values are needed. EPS rated at R-4 per inch of thickness can provide up to 2 times greater insulation than traditional insulating materials of the same thickness.
Other rigid foam insulation materials require testing to determine their long-term thermal resistance (LTTR) which can add to product development costs and render a calculated ‘guess’ at the insulation’s performance over time. EPS does not have to conduct such tests because it does not experience thermal drift, meaning its R-value remains constant throughout the life of the building.
EPS Slab-On-Grade floors are one example that demonstrates energy savings. According to the U.S. Department of Energy (DOE), Office of Building Technology, insulating the exterior edge of the foundation slab can reduce winter heating bills by up to 10 to 20 percent1. An insulated slab also provides thermal mass to store heat and moderates indoor temperatures.
Studies designed to evaluate newer building systems applications, like structural insulated panels (SIPS) and insulated concrete forms (ICFs) have shown increased energy savings over competing materials, up to 25%. In a 1993 test conducted by the Florida Solar Energy Center, a building constructed with EPS insulation tested at only 1.8 air changes per hour (ach) versus 3.9 ach measured for a conventional, stick frame construction. Similar results for ICFs made using EPS are shown in a study performed by Oak Ridge National Laboratory, “Dynamic Thermal Performance and Air-Tightness Effects of Concrete and Masonry Walls” and the Department of Housing and Urban Development, “Insulating Concrete Forms: Installed Cost and Acoustic Performance. Houses built with ICF exterior walls require an estimated 44% less energy to heat and 32% less energy to cool than comparable frame houses.
When properly installed, EPS insulation reduces the transfer of heat flow, either out of or into the building. Structural systems like SIPs and ICFs further improve the resistance to heat flow by providing tighter construction. Additional studies from the Cement Association of Canada (CAC) and the Northwest Territories Housing Corp. (NWTHC) show that homes constructed with ICFs above and below grade wall construction have reduced air infiltration compared to other wall assemblies.
1. Slab Insulation Technology Factsheet. Office of Building Technology, State & Community Programs Energy Efficiency & Renewable Energy. U.S. Department of Energy. December 2000.
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