Everyone is talking green and selling green–green fashion, green furnishings, green houseware, green building materials. But are we sure they are “green” enough?
One of the related concepts of carbon footprint is embodied energy. Another way to determine the greenness of a specific building material or product is to look at its embodied energy index.
Embodied energy is the sum of all the item’s/material’s energies used in processing (from extraction/harvesting of raw materials to manufacturing), packaging, transportation to the site, construction and eventual use, and finally its disposal. Put simply, embodied energy looks at the entire lifecycle of the material and computes how much energy is consumed.
Embodied energy is also called by different terms: cumulative energy demand, embedded energy, virtual energy or hidden energy. The relation of embodied energy to carbon footprint is through the CO2 byproducts of the energy consumed by the material. Meaning, the more energy used to harvest, manufacture, transport, use, and dispose a product, the more CO2 is being produced.
Therefore, the smaller the embodied energy of the product is, the “greener” it becomes.
Bangui Windmills in Ilocos Norte, Philippines. Photo by Sir Mervs
SOURCES OF ENERGY
The embodied energy of materials is mostly similar from region to region, regardless of where it was manufactured. Although most material production processes are universal, the type of energy utilized may not be the same. A country whose power plants are mostly coal-fueled will have its products having a higher carbon footprint than a country which relies on geothermal or wind power (for example Iceland, which uses mostly geothermal and hydroelectric power) .
IMPORTED VS. LOCAL
Be careful on buying imported products and building materials. Even if the product from another country is green, it may not be the greenest decision to purchase it. Transportation costs will add a significant amount to its embodied energy. Plus, the energy used to process the product may not be from renewable sources. Of course, recycled materials and handmade products have a lower embodied energy. Therefore, make sure that the other stages in the product’s lifecycle saved/will save on energy to compensate for its international shipping. Otherwise, love your own and buy local products! You do not only help the environment, you also help the local economy.
EMBODIED ENERGY INDEX
Most computations for the embodied energy only consider the manufacturing process (starting from the acquisition of raw materials to the finished product ready for shipping).
At the bottom are some values from the Center for Building Performance Research, Victoria University of Wellington, New Zealand to give you a comparison of the commonly used building materials today. (Unfortunately, we don’t have values yet for our country.)
Hope this will help you make greener choices and purchases next time. -green guide
|Aluminum, virgin||191 MJ/kg|
|Aluminum, recycled||8.1 MJ/kg|
|Concrete hollow block||0.94 MJ/kg|
|Glass, float||15.9 MJ/kg|
|Paint, water-based||88.5 MJ/kg|
|Steel, virgin||32 MJ/kg|
|Steel, recycled||10.1 MJ/kg|
|Timber, softwood, kiln-dried||1.6 MJ/kg|
|Timber , hardwood, kiln-dried||2.0 MJ/kg|
Tags: carbon footprint, conscious living, embodied energy, embodied energy index, green, green architecture, green design, green products, interior design
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