Recently during a webinar I was conducting, the topic came up of embodied energy versus operational energy. This topic continues to come up as building scientists evaluate systems with regard to their sustainability.
There are two things that can make a product green. It can be green in its manufacture or it can be green in its application. One of the important topics for understanding the manufacture or delivery of a product is the concept of embodied energy – how much cumulative energy went into the extraction of the raw materials, the manufacture of the product and the transportation of the product to its final application. This is the concept of embodied energy. Operational energy relates to how much energy the product uses or can save once it has been applied or installed into a system.
For instance, look at insulation. Many types of insulation are actually very energy intensive in their manufacture, however once they are installed they can save many times over within the very first year of their application. A perfect example of operational energy is fiberglass insulation. In its first year of use, fiberglass insulation can save 12 times the amount of energy it took in making and transporting the product.
So let’s not throw out the baby with the bath water. Sometimes, material that is superior in performance with regard to the life cycle of a building may have a little bit of negative upfront energy costs, however in its use can be very positive.
So don’t make a judgment solely based on the embodied energy but rather on the life cycle of the project to determine if it is positive or negative for the project itself.
Lucas Hamilton is Manager, Building Science Applications for CertainTeed Corporation