Wrong Turn Taken: Embodied Energy & LCA

Have you seen the claims of cellulose insulating materials to be the “Greenest of the Green”? Embodied Energy is used as a basis for the claim. Cellulose has many noteworthey Green attributes, but if you look to the footnotes on the embodied energy tables for insulating materials you will see that the numbers include the “caloric BTU value of the EPS”. That is to say that the BTU value of the EPS was included as if the EPS feedstock were going to be burned for fuel. Cellulose insulation on the other hand does not include the BTU value of the wood it is made from if the wood were burned thus severely distorting the comparison of cellulose to EPS insulation. Petroleum and Natural Gas which are the primary feedstocks in EPS should be viewed as  minerals, of which there is a finite supply.  The choice seems to be; should we burn gas and oil and dump more CO2 and other pollutants into the atmosphere or make it into a durable good that can be recycled indefinitely and save huge amounts of energy with that durable good.

Embodied energy is a factor used in Life Cycle Analysis LCA to compare the merits of materials, processes, etc. When embodied energy includes all the important energy inputs into the extraction, transport, processing and disposing or recycling of a material it can be very useful. However if a short term view is adopted which puts more  emphasis on supply side dynamics than on preservation of resources then we have a distorted result which can lead us down the wrong path of material selection. Most of the best known LCA tools, like the Athena model, treat EPS in this fashion.  I would strongly argue that including the energy value of burning a raw material in embodied energy calculations is just this type of inappropriate emphasis on short versus long term environmental vision. We should be preserving petroleum products for long term durable goods manufacture, which in the case of EPS insulation, saves about 100 times more energy over the life of a building than the energy used to produce it. And the bonus is that we still have the polystyrene molecule to reuse over and over again and the carbon in the petroleum is sequestered keeping it out of the atmosphere. Since plastics account for less than 3% of all petroleum and natural gas consumption and in most cases is very recyclable, its makes much more sense to preserve oil and gas for these types of use and replace them with renewable energy sources. This would be a Win, Win, Win for us all.

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2 Responses

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