(CNN)The homes of wealthy Americans generate around 25% more greenhouse gases compared to lower-income residences, mostly because of their larger size, a new study found.
In some particularly affluent US suburbs, emissions are up to 15 times higher than nearby neighborhoods, according to the study published Monday in the journal Proceedings of the National Academy of Sciences.
"This is like a tale of two cities in carbon form," said Benjamin Goldstein, a postdoctoral research fellow at the Erb Institute at the University of Michigan and a co-author of the study. "Income and greenhouse gases rise together."
Though American homes are becoming more energy efficient, they still account for roughly 20% of all heat-trapping gas emissions in the United States. The combined carbon footprint of all American homes is roughly equal to the entire country of Brazil, the researchers say.
The study used data on 93 million homes across the contiguous United States to determine the main drivers of household emissions.
The researchers found that generally, homes in states with milder climates use less energy than comparable ones in colder climates.
Based on energy data from 2015, the most energy-intensive states were Maine, Vermont and Wisconsin, while the least energy-intensive that year were Florida, Arizona and California.
These findings show that wealth is just one part of the equation, says Jonathan Foley, the executive director of Project Drawdown, an environmental non-profit focused on climate solutions.
Larger homes -- because they require more heating, cooling and lights -- produce a bigger carbon footprint. But the study also shows that in cold weather states, homes produce high emissions because they require more energy to heat.
"Part of it is wealth and consumption," Foley said. "Then there are a lot of things outside our personal control -- like policy, infrastructure and weather. Are you going to tell people in Minnesota not to heat their homes?"
The researchers also focused on Boston and Los Angeles because of their divergent climates and contrasting housing stock to examine how carbon footprints can vary across large urban areas. Boston is cold much of the year and has many older homes, while Los Angeles is warm and much of its housing was built after 1950.
In both cities, the study found that income correlates positively with per capita emissions. Affluent neighborhoods produce higher emissions, and most neighborhoods with low emissions were below the poverty level. Suburbs often have higher greenhouse gas emissions than US inner cities, according to a study by the University of California, Berkeley in 2013.
Vincent Reina, an assistant professor in the Department of City and Regional Planning at the University of Pennsylvania, agrees that wealthier residents own large homes that require more energy, but says low-income residents also produce significant emissions because they often can't afford to make their homes energy-efficient.
"For higher income individuals, it's a function of choice," said Reina. "For lower income individuals, it's a function of constraints."
The study's authors say improving energy efficiency in the home is a huge opportunity for homeowners -- and especially wealthy ones -- to lower their energy usage.
Upgrading windows to improve insulation, switching to environmentally-friendly heat pumps instead of air conditioners or furnaces, and installing solar energy systems are just a few of the biggest ways homeowners can reduce their carbon footprints and power bills.
The researchers also say that improving in-home energy efficiency, decarbonizing the electrical grid and reducing fuel consumption are key to achieving the Paris Climate Agreement targets, which call for emissions to fall 80% from 2005 levels by the year 2050.
"Those who emit the most are probably in the best position financially to abate those emissions," said Goldstein. "But we also need all hands on deck to deal with this problem, so we need to address low-income households."
The study's authors say the government -- using carbon taxes -- could fund updates on homes in low-income neighborhoods, which would cut energy bills for residents and reduce emissions.
The study recommends newly-constructed homes be smaller, and outfitted with energy-efficient heating and cooling systems. Researchers also say the United States would have a better shot at meeting Paris Climate agreement targets if neighborhoods were zoned to be denser.
"The technologies are there," said Goldstein. "Getting to Paris (Climate Accord targets) doesn't hinge on some miraculous technological solution. The technologies exist today -- it's about getting them to (people)."