Across Georgia, eco-certified buildings have become more common due to their ability to boost energy efficiency, lower operating costs, and shrink carbon footprints. But are these benefits shared equitably across the state?

That’s the central question explored in this blog, which takes a closer look at how green commercial buildings are distributed throughout Georgia—and what that says about equitable access to climate solutions. Using two powerful tools borrowed from economics—the Gini coefficient and the Lorenz curve—Drawdown Georgia researchers are uncovering patterns of inequity in the built environment.

Keep reading to learn how these research tools reveal disparities in green building access, why this matters for communities and businesses, and how data from the newly-launched Drawdown Georgia Solutions Tracker can inform smarter, more equitable decisions going forward.

The History of Measuring Income Inequality

The numerical Gini coefficient, and its visual counterpart the Lorenz curve, concisely convey the level of inequality in a community. 

Developed by Italian statistician and sociologist Corrado Gini, the Gini coefficient measures inequality within a given group. It ranges from 0 to 1, where 0 indicates complete equality (everyone shares the benefits equally) and 1 indicates complete inequality (one person receives all the benefits, while everyone else receives none). A lower Gini coefficient suggests a more equal distribution of benefits, while a higher one indicates greater inequality.

Developed in 1905, the Lorenz curve derives its name from its creator, an American economist named Max Lorenz. A Lorenz curve is a graph that shows how income, resources, or other benefits are distributed within a community. The horizontal axis represents the cumulative percentage of the population, from poorest to richest, while the vertical axis shows the cumulative share of income earned by the community as a whole. 

The Lorenz curve displays the data on the distribution of income or benefits to the community. A straight diagonal line is also drawn on the graph to show what perfect income equality would look like—where, for example, 25% of the population earns 25% of the income, 50% earns 50%, and so on.

The divergence between these two lines indicates the degree of inequality of distribution in that community. 

Seven years after Lorenz’s innovation, an Italian statistician named Corrado Gini iterated on the Lorenz curve with a coefficient expressing the extent of inequality as a number between 0 and 1, with 0 representing perfect equality of distribution and 1 representing perfect inequality. 

In general, multilateral organizations such as UNICEF consider Gini coefficients greater than 0.4 as indicative of high inequality. The Drawdown Georgia research team uses the Gini coefficient to measure how equitably different climate solutions are distributed within the state of Georgia. 

Why Is Equity Important?

Focusing on issues of equity and climate justice as we scale climate solutions in our state is a key element of the Drawdown Georgia framework. The specific threat of climate change's impact on disadvantaged communities makes the pursuit of equity most crucial. 

If a climate solution is clustered among a few counties only, we can assume that although there is immense potential for statewide adoption, there are barriers preventing the spread of that climate solution that can be addressed with good policy. 

To address these issues, the Drawdown Georgia research team adopted Gini coefficients and Lorenz curves to help better understand uneven access to climate solutions across the state. The Drawdown Georgia Solutions Tracker is a new tool to help researchers, policymakers, advocates, and business leaders visualize inequalities around climate solutions. 

The Tracker offers maps of the state that utilize color-coding to indicate which counties have the highest prevalence of 16 of the 20 Drawdown Georgia climate solutions, and which counties don't, to highlight areas of progress and areas needing greater improvement.

The Research Process: Tracking Commercial Buildings

With the guidance of Drawdown Georgia researcher Dr. Marilyn Brown, I embarked on research on Georgia’s eco-certified commercial buildings that expands on previous research on K-12 enrollment in eco-certified public schools. Modeling eco-certified commercial buildings required different data and different calculations than modeling eco-certified schools. 

I first decided to evaluate commercial building space. While school data was provided by Kennesaw State's Dr. Pegah Zamani, who also provided support for my capstone, I procured commercial building data from the Green Building Information Gateway, which has information on the location, green building certification, square footage, and building purpose for green buildings all over the world. 

Then, I filtered the database to only consider Energy Star- and LEED-certified buildings located in Georgia. Only these two certifications were considered because they are the strictest and most prominent designators of "green buildings."

I then geocoded the location of each green building to their respective counties using ArcGIS, confirming with databases from Energy Star and LEED and downloading shapefiles from the U.S. Census Bureau. Next, I examined the list of all buildings to eliminate any extra certifications and those designated as military, industrial, or residential buildings. 

To find the total commercial building space for each county, I consulted the 2018 Commercial Buildings Energy Consumption Survey. An R script I devised calculated both the total commercial building space and the total Energy Star or LEED certified commercial building space for each county. At long last, this data was used to calculate a Gini coefficient and Lorenz curve, using another R script. 

Exploring Equity and Green Buildings: Gini Coefficient Implications

This research process calculated the Gini coefficient for commercial building space as 0.39, revised from an earlier value of 0.37, which included military, industrial, and residential buildings. In contrast, the Gini coefficient recorded for energy-efficient schools is 0.71. 

This means that the top 25 percent of counties with the most commercial building space had 50 percent of the green building space. In fact, the two most populous counties in Georgia--Fulton County and Gwinnett County--also have the most commercial building space of all counties. Together, these two counties represent 18.8% of Georgia’s population, 32.2% of its commercial building space, and 57.9% of its green building space. These counties have a low percentage of neighborhoods designated by the U.S. government’s Climate and Economic Justice Screening Tool as "disadvantaged," overburdened, and underserved.

Takeaways From the Research on Equity and Green Buildings

What does this finding mean for those interested in solving environmental problems equitably and effectively? It calls for developers and other stakeholders in the commercial building industry to do more than just support the creation of green buildings; they should also consider where green buildings are being built or renovated. 

The barriers to equity are structural: the concrete changes builders and owners must make for their projects to qualify as "green" are expensive enough to effectively block poorer neighborhoods from this technology. Even the process of certification itself is a considerable expense in both time and money. 

Nevertheless, it is essential that policymakers commit to equity and confront these barriers. When a local neighborhood is home to schools lit with LED lighting, supermarkets outfitted with insulated walls and ceilings, and stadiums bedecked with solar panels, that neighborhood reaps benefits not only in its environment but in the health of its residents and its economy. It should be our goal to realize these benefits in neighborhoods and counties across the state of Georgia.

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