Unsurpassed Strength and Durability
Strength of a structure is defined as “that load which effects a destruction of the structure.” Durability is defined as “the ability of a structural design to resist deterioration and damage from environmental factors.” The Energy Mass™ Wall employs three basic materials that have a track record of being both exceedingly strong and durable. The material used on the outside, to battle the elements of the environment, is concrete which was employed in Roman structures that are still functional 2,000 years after they were built.
Between and protected by the two skins of concrete on its sides and a bond beam and foundation top and bottom, is a type of closed cell foam that has an expected useful life of 100 years when installed in a wood framed building. No one knows the expected life of the foam when installed in the Energy Mass™ wall, but because it is completely sealed from the principal factors that lead to foam deterioration (sun, water, and air) we expect the useful life to be substantially longer – most likely hundreds of years. However, if the foam did for some reason ever deteriorate it wouldn’t change the performance of the Energy Mass Wall because the left over “dead air space” would effectively provide an equal insulation value.
The two principal loads that effect a wall are (i) compression, which would typically result in a buckling failure long before the material itself crushed under the load, and (ii) bending, which occurs when wind or seismic forces act on the face of the wall causing it to bend between the two points of its attachment – at the foundation and at its intersection with the roof plane. Both potential failures (buckling and bending) are governed by a geometrical property of the assembly known in engineering terms as the moment of inertia – given the symbol I.
Notice that in the buckling equation, which predicts the compression force that will cause onset of a buckling failure, I is in the numerator - meaning that the larger the I the greater the force that can safely be put on the wall before it begins to buckle. In the bending equation, failure of the wall will initiate when the stress [σ] in the outer fiber exceeds the strength of the material. Because I is in the denominator this means that the greater the I the lower the stress for a given loading and therefore the greater I is the more capacity the wall will have to resist high wind and earthquakes.
The diagram below shows the moment of inertia I for a 12“ wide by 6” thick solid concrete wall. This value is 216. The energy mass residential section which uses the same amount of 6” total thickness of concrete but spread out into two 3” thick skins have an I of 2400.
The conclusions: The Energy Mass™ wall is more than 10 times stronger for resisting wind and earthquakes and can carry more than 10 times the amount of compressive force than a 6” concrete wall.
