Understanding Households’ Impacts on Energy Consumption

By Marlene Cimons, National Science Foundation

When tallying the nation’s overall output of carbon, the American household counts for a lot.

“If we are looking at how to reduce carbon emissions, households become very important,” said Lawrence A. Baker, a senior fellow at the University of Minnesota Water Resources Center. “This was not true 50 years ago. But today, close to half of the direct carbon emissions come from households. We are now trying to figure out the indirect emissions.”

Baker and his research collaborator, Joseph McFadden, assistant professor of terrestrial biophysical processes in the geography department of the University of California at Santa Barbara, are studying the factors that influence how people use energy—how they manage their land, choose their cars and other transportation, what they eat, how much they exercise and how they use energy in their homes. They hope to better understand the household cycle that results in the emissions of carbon, nitrogen and phosphorus.

“We are trying to translate all of those things into the movement and flow of those elements,” McFadden said.  “These elements cycle through the globe, through the whole Earth system, and through peoples’ households. When somebody eats a cheeseburger, they put carbon out when they run around the block. When they use the restroom, they put out nitrogen and phosphorus. We are trying to account for all of this.”

Recognizing that home-based decisions contribute to environmental pollution, as well as to environmental solutions, the scientists have launched a research project to calculate the in-and-out flow of these elements through a sample of households. The hope, ultimately, is that the data they collect will have an impact on policy and decision-making aimed at reducing local and global pollution that results from household activities.

The Twin Cities Household Ecosystem Project is studying 3,100 households along an urban to exurban stretch of the Saint Paul-Minneapolis metropolitan area, a 55-kilometer distance that includes the counties of Anoka and Ramsey, “ the whole spectrum of households from the inner city all the way out to the last suburban vestige,” McFadden said.

Including cities in the  mix is important because “cities are also ecosystems that are really intense,” McFadden said. “There is a very intense flow of stuff in cities because they are concentrated. Understanding this is an important key to sustainability at the national level. If you can’t understand the ecology of cities, you will have a hard time across the whole country, and the world.”

“We are looking at the whole flow,” he added. “We want to know what cars people use, what they eat, whether they exercise, the cars they drive--the make, model and age--where they drive and how often, whether they fly, magazines and newspapers that come in, how they use their land--all of the consumption.”

The three-year study is funded by a $1.5 million National Science Foundation grant as part of the American Recovery and Reinvestment Act of 2009. The award has enabled the research team to hire numerous students and extra staff to conduct their investigations. “We never would have been able to do this without the considerable ramping up of resources and staff,” McFadden said. “It’s made a dramatic change in the scale at which we will be able to address these questions.”

The nation’s energy use has not declined since 1970, despite the introduction of more efficient energy-using products, according to Baker. “Everything has become more efficient—cars, air conditioning and heating units, airplanes—but we consume more of everything,” he said. “We fly more than we used to. We drive more. We have better air conditioning, but bigger homes. We even eat 25 percent more calories than we did then. Our increase in efficiency has been offset by our increase in consumption.”

Thus, “I am convinced we will not get there through technology alone,” Baker added. “We have to make choices about the energy we consume. We have to understand why we make these choices. That is the purpose of the study.”

In addition to extensive and detailed surveys about home energy use, decision-making, and respondents’ attitudes and beliefs about energy consumption, the researchers will, with permission, examine homeowners’ public utilities records and study their individual landscapes, literally looking at “everything not inside the house,” McFadden said. “We ask permission to come to the property and walk across it, measuring trees, examining the entire lawn area, which we put into ecological models,” he said.  “We want to know about fertilizer, grass recycling, the trees they grow, even whether they pick up the feces of their pets.”