What Is Emergy? And What Does It Have to Do With Homebuilding?

October 4th, 2023 by Editor

While the word ‘emergy’ might raise a red flag for most spell-check systems, it isn’t a typo. Rather, it’s an analysis theory that provides an energy-related base for assessing the properties of “products and services of social, economic and ecological compound systems,” say researchers from the Institute of Economics and Management, Shanghai University of Electric Power, Shanghai. In simpler terms, it’s the amount of energy consumed in direct and indirect transformations.

In a paper published on Nature.com, researchers say they looked at the use of emergy footprint models as a source for assessing the ecological effect life cycle of homes. According to Mengyang He, Yang Wang, and Hoatian Ma, “China’s ecological efficiency of the housing sector is characterized by improvement.” Meanwhile, more than 75% of the emergy footprint of a house with a 50-year life cycle went to operation and maintenance. The construction phase of housebuilding accounted for 22% of related emergy. But the imbalance of energy consumption for those two phases is flipped when it comes to the intensity of the emergy footprint, the trio writes. The emergy footprint of house construction is 4.82 times more “intense” than that of operation and maintenance.

He, Wang, and Ma chose to use emergy footprint models because the method “combines the advantages of the ecological footprint model and emergy analysis theory, and thus has developed into a new quantitative evaluation method of ecological environmental impact.”

Here in the U.S., you’re more likely to hear terms such as “life cycle assessment” and “environmental product declaration.”

As for researchers at Shanghai University, their study shows that “[r]educing energy consumption and carbon dioxide emissions in the operation and maintenance stage is the key to reducing the life cycle emergy footprint of house buildings. The ecological impact coefficient of house buildings is negatively exponentially correlated with their service life.” According to footprint models, it would take 37 years for the hypothetical house to break even in an ecological sense, they say.

That’s longer than the life expectancy of some building materials.

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