Understanding Your Ecological Footprint

Hi. I'm Maria Saxton, Ph.D. I'm introducing myself because this in-depth article for Rise is unique. I have always been very interested in the tiny home movement. But I could not find a lot of research or data that would back up people's claims that tiny homes are more sustainable. So for my Ph.D., I wrote my dissertation on the Ecological Footprints of Tiny Home Downsizers. And now, I have the opportunity to translate an academic paper into what it means in the real world. So bear with me. There are nuggets here, especially if you wonder about your environmental impact! 

Ecological Footprint Recap

In my first story, I wrote that an ecological footprint is a measure of the demand that human behavior has on the biosphere. You can use it to show the connection between human behavior and the impact on the environment. Ecological footprints can also be used to examine resource demand, distribution of natural resources, address human resource consumption, and educate people on their consumption habits. Many calculators exist to measure ecological footprints. Because of this, it is often difficult to know which is the most appropriate for your needs. 

So how did I figure that out? In two relatively short phases, I was able to determine which ecological footprint calculator made the most sense for my research, which looked at small-scale housing. This article provides a simplified overview of my approach for comparing seven of the most popular ecological footprint calculators.

Identifying Popular Ecological Footprint Calculators

My research, which will be explored later in this series of articles, measured the ecological footprints of people who downsize to tiny homes. This exploration begged the question, which ecological footprint calculator was the best to answer my research questions? Specifically, I wanted to know which calculators were the most comprehensive and which calculators were the most relevant to small-scale housing. For those interested in learning how to compare calculators effectively or know which calculator is best suited to measure your footprint, you can easily replicate this process. 

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When comparing various ecological footprint calculators, the first step is to identify which are the most popular. The easiest way to do this is through online searchers through various search engines (Google, Bing, Yahoo!, etc.). Through ten different search engines, I searched the phrase "ecological footprint calculators," tracking which calculators showed up in the first two pages of search results. I found the following seven calculators to be the most popular at the time of this exercise: 

1. Bioregional Ecological Footprint Calculator 
2. Center for Sustainable Economy Ecological Footprint Calculator
3. Eco Campus Ecological Footprint Calculator 
4. Global Footprint Network Ecological Footprint Calculator 
5. Islandwood Ecological Footprint Calculator 
6. The Nature Conservancy Ecological Footprint Calculator 
7. World Wildlife Fund Network Ecological Footprint Calculator 

It is important to note that since I compared these seven calculators in early 2018, three calculators (Eco Campus, the Center for Sustainable Economy, and Islandwood) are no longer available online. 

The next step was to look at the literature on ecological footprint calculators. Several academic publications compare calculators, such as Collins and Flynn (2015) and Fernandez et al., 2016. Both papers, as well as most others, identify the Global Footprint Network calculator to be the most comprehensive. But I wanted to be sure and compare them myself, which led me to phase one.

Phase One: Calculator Comparison - Coverage Scores

When reviewing each specific calculator, I discovered a discrepancy among which impacts each one measured. For instance, one calculator would have five measurement points about the build of one's home, while another would have a dozen. It seemed logical, as the first phase of comparison, to determine the coverage of the calculators. 

First, I compiled the question and answer choices from each calculator into one matrix and compared them to determine which calculators were the most comprehensive. By comprehensive, I mean covering the broadest range of potential impact-producing behaviors and choices made by individuals. Then, I grouped the data into four of the main footprint components identified through the literature: housing, food, transportation, and goods. I combined similar questions and assigned labels to determine what environmental impacts each of the seven calculators measured. 

Comparing Calculator Questions

The matrix took each calculator's questions and categorized them into these 70 measured impacts. Calculators were given a "coverage score" to determine which ones covered the most substantial amount of material. A score of 25, for instance, meant that a calculator included 25 of the 70 possible measured impacts identified earlier. Below are the coverage scores for each of the top seven categories: 

1. Bioregional Ecological Footprint Calculator (33 points)
2. Global Footprint Network Ecological Footprint Calculator (29 points)
3. Center for Sustainable Economy Ecological Footprint Calculator (29)
4. World Wildlife Fund Network Ecological Footprint Calculator (24) 
5. Eco Campus Ecological Footprint Calculator (18)
6. The Nature Conservancy Ecological Footprint Calculator (17)
7. Islandwood Ecological Footprint Calculator (13)

As you can see, three of the seven calculators had relatively higher scores than the rest. Those covered the most significant amount of material and behaviors that could potentially impact someone's environmental impact. For the next phase of comparison, I decided to only look at these top three. 

Phase Two: Calculator Comparison - Relativity Scores

I then compared the top three most comprehensive calculators to determine relevance to my specific research that looked at ecological footprints when people downsize to tiny homes. Suppose you, the reader, are interested in comparing ecological footprint calculators yourself for a different purpose. In that case, this step could look slightly different for you. 

For this phase, I created another matrix that included the comprehensive exercise from the first phase—but only used the top three calculators. I then looked through the literature on tiny home living to determine which of the 70 possible measured impacts were the most relevant to tiny home living. 

Examples include items such as electricity, growing food, size of the home, energy efficiency of the house, the presence of renewable energy, and more. In total, I identified 19 out of the 70 possible measured impacts (or about 27%). I then compared the questions from the top three most comprehensive calculators to determine their relevance to the tiny home-related effects.

The list below displays the "relativity score" for the top three most comprehensive calculators. 

1. Global Footprint Network Ecological Footprint Calculator (14 points)
2. Bioregional Ecological Footprint Calculator (12 points)
3. Center for Sustainable Economy Ecological Footprint Calculator (12 points) 

As such, I used this calculator in my research to measure tiny home downsizers' ecological footprints.

If you are interested in learning more about your ecological footprint, the key is to choose a calculator that fits your needs and goals. The two phases I used to compare the top seven calculators were somewhat tedious but easy to replicate. At a minimum, it is essential to review the content of multiple calculators before deciding which is the best for you. There are so many great tools out there, and understanding which is the best for your needs will help you better understand your environmental impact. 

The following section will explore the five main components of the Global Footprint Network ecological footprint calculator. You'll also learn how you use this tool to understand your environmental impact as well as the limitations of ecological footprint calculators in general.

The Global Footprint Network Tool: A Deeper Dive

The Global Footprint Network online ecological footprint calculator is the most well-known and widely used ecological footprint tool available today. It was developed by both the Global Footprint Network and its 75+ partner organizations, including many organizations from academia, consulting firms, corporations, governmental organizations, and non-governmental social benefit organizations. To be a partner of the Global Footprint Network, these organizations must comply with the ecological footprint standards.

Initially establishing the Global Footprint Network in 2003, Mathis Wackernagel and William Reese were the first individuals to calculate an ecological footprint systematically. Now the President of the Global Footprint Network, Wackernagel has worked towards developing and creating standards for the ecological footprint calculator to provide guidelines ensuring their accuracy and transparency. Data sources, scopes, conversion factors, and communication processes are outlined using the ecological footprint standards. Committees consisting of academics, government officials, and professionals regularly review these standards, with the most recent revision developed in 2009.

Serious Data

The personal ecological footprint calculator is based on National Footprint Accounts (NFA) data for selected countries. The NFA program provides a framework for calculating a footprint and annually measures the ecological footprints of countries worldwide from 1961 to the present day. The purpose of the NFA is to provide a comprehensive and transparent calculation methodology, and these editions are available online as downloadable files provided by the Global Footprint Network. These are worth a look if you are interested in learning more about the NFA program.

A specific country's ecological footprint relies on regional data on resource consumption—such as energy, water, land use, logging, fishing, etc. In short, the calculation adds imports and subtracts exports from the country's overall production. The NFA uses about 15,000 data points per country per year and includes more than 200 countries, territories, and regions. For each country per year, over 5,400 raw data points are used. In the 2011 edition of the NFA, approximately 61 million data points were used in total. The data sources for the NFA include United Nations data sets, including the Food and Agriculture Organization, United Nations Commodity Trade Statistics Database, UN Statistics Division, and the International Energy Agency. Additional data includes peer-reviewed science journal articles and thematic collections. The NFA is used and supported by more than 70 organizations, making it the most widely used national accounting methodology.

A Closer Look at the Global Footprint Calculator Methodology 

An ecological footprint represents the land area necessary to sustain current levels of resource consumption and waste by a population, activity, or individual. An ecological footprint calculator measures the amount of biologically productive land and sea area an individual, group of individuals, or activity needs to provide for their consumption.

To calculate the area required, ecological footprint calculators use yields of land types, including cropland, forest, grazing land, fishing ground, and built-up land. The measurement unit is in global hectares (gha). A global hectare equates to 10,000 square meters or 2.471 acres and is approximately the soccer field size. Global hectares (gha) are used as a unit of measure because they look at the physical area across various land-use types. 

The calculation methods of the Global Footprint Network calculator are standardized and use a standard set of easily accessible data, ensuring their credibility and consistency. All steps of an ecological footprint calculation—including raw data—are found in the "Working Guidebook to the National Footprint Accounts." Further, the methodology of the Global Footprint Network ecological footprint calculator is regularly reviewed and improved by two review committees (the Standards Committee and the National Accounts Committee), partners of the Global Footprint Network, and other stakeholders, including other national governments.

How to Use the Global Footprint Calculator

You can find the Global Footprint Network's online ecological footprint calculator tool on their homepage by clicking "Calculate Your Footprint." Once you get to the calculator itself, it will first prompt you to log in with Facebook or provide your email. But don't worry, they won't bombard you with emails. Then, the calculator will have you answer a series of questions divided into three main categories: food, housing, and transportation. The number of questions you answer will depend on how much data you want to provide. 

The national per-person ecological footprint is allocated to five ecological footprint components: food, housing, transportation, goods, and services. The online calculator asks questions that either increase or decrease different parts of one's ecological footprint relative to national averages. For example, if you indicate that you eat twice as much beef as the average American, your "beef" footprint will double. Your overall ecological footprint value will increase. If you indicate you eat very little beef, you will receive a fraction of the average beef value, resulting in a smaller overall ecological footprint.

Food

The calculator itself starts with the Food section. You'll first need to toggle the slider bar to share how often you eat animal-based products. For the most detailed and accurate footprint, you'll want to select "Add Details to Improve Accuracy" whenever possible, as shown in the image below. Next, you'll share the percentage of your food that is unprocessed or unpackaged. The quiz also asks what percentage of your grocery purchases are locally grown. Again, make sure to add extra details for this step. 

Housing

The next section asks you questions about your house—starting with your current housing type (apartment, single-family home, etc.). While relatively straightforward, make sure to read all the choices before selecting the one that best fits. The quiz will also ask about your home's construction material. If you are not sure, a typical home is stick-built (framed with wood).

This section will ask how many people live in your household and the square footage of your home. If, for example, you have a child in college who comes home only for holidays, be sure to answer the occupancy question for a typical month. If you are unsure of your home's square footage, you can refer to an online guide to estimate or measure. You can also search your address on Zillow (which will often provide standard information like square footage) or consult official documents for your home. 

The Housing section will also ask if you currently have electricity in your home (in most cases, yes) and how energy efficient your home is. Make sure to read the descriptions for energy efficiency carefully. Older homes will often be less efficient than newer homes, so also consider the age of your home when answering this question. You'll be asked to share what percentage of your home's electricity comes from renewable resources, either directly or through purchasing green power. The quiz asks you how much trash you generate compared to your neighbors. You can be more specific by selecting "Add Details to Improve Accuracy." It will also have you reflect on how much paper and plastic you recycle. 

Transportation

In this third section, the quiz begins by asking you how many miles you typically drive in a week. Estimate to the best of your ability and average distance traveled if this number fluctuates week to week. It will also ask how efficient your car is and how often you carpool. If you do not own a car, leave these sections as is. If you indicated your driving distance was 0, then this will be reflected in your footprint. The next question examines the use of public transportation (by bus and train). The last question asks how many hours you fly in an average year. Be sure to carefully consider your answer to this question, as this can significantly influence your footprint. 

Results

Once you have answered all the questions, you will learn your calculated ecological footprint!

What Does It All Mean?

In this final section, we will help you understand what your ecological footprint results mean, how they compare to national (and international) averages, and some limitations of this tool.

Your Footprint Results: What You'll See 

After you complete the calculator quiz, you'll receive your results. The first results page you'll see will look similar to the screenshot below. We'll break this down so that you can easily understand what this means.

This date is calculated using data from the Global Footprint Network's National Footprint Accounts (NFA). The simplified calculation is as follows: 

"The Earth Overshoot Day = [Planet's Biocapacity / Humanity's (or Personal) Ecological Footprint] x 365 days/year"

The general trend has been that the world's Earth Overshoot Day is earlier and earlier each year. In 2019, it was July 29th, the earliest ever. There is an initiative to #movethedate back five days every year—which is part of what we'll discuss in the next article. 

By clicking on the green label "See Details," you'll come to a page that looks similar to the one below but with different values. This page will show your overall ecological footprint value, carbon footprint value, and a visual breakdown of your footprint.

Your ecological footprint value is measured in global hectares (gha). A global hectare equates to 10,000 square meters (or 2.471 acres) and is approximately the size of a soccer field. Global hectares (gha) are used as a measurement unit to look at the physical area across various land-use types. My ecological footprint is 2.9 global hectares. This result tells us that my lifestyle requires about three soccer fields worth of biologically-productive land to provide enough resources. 

As mentioned earlier in this series, a carbon footprint is another popular measurement of environmental impact. As seen above, a carbon footprint is a small component of someone's overall ecological footprint. A carbon footprint is measured in tonnes per year. It is impacted by things like transportation habits and the consumption of animal-based products. My carbon footprint comprised 50% of my overall ecological footprint, meaning that this is an element I need to work to reduce. 

The national per person ecological footprint includes five footprint components: food, housing, transportation, goods, and services. It also covers land types (forest, cropland, energy, fish, grazing land) using a country's average consumption profile. The pie chart displayed in your results will be dependent on your answers to the calculator questions. For instance, I shared that I very infrequently consume fish food products. The calculator's results reflect the lack of fishing grounds required for my lifestyle. 

In the top right corner of this results page, you'll see how your ecological footprint is allocated among the five footprint components. My shelter/housing component is the largest, likely because of the older home I live in that has somewhat outdated appliances and a leaky building envelope. My mobility/transportation component is the lowest for multiple reasons. I drive a fuel-efficient car, work primarily from home, and typically only travel long distances on the weekends when I am carpooling with friends or family. I make an effort to reduce airplane travel when possible. 

One trick: If you hover over each column, you can see each component's actual footprint value.

To improve the comprehensiveness of the ecological footprint calculator, starting in 2019, the Global Footprint Network launched the "The Ecological Footprint Initiative." This is a partnership between the Global Footprint Network and York University in Toronto, Canada. This initiative's goal is for researchers to further develop the methodology and improve the data behind the current ecological footprint calculator. Likely, this will improve the existing limitations of the ecological footprint calculator to make it representative of the range of potential impact-producing behaviors and choices made by individuals.

Article by:

Maria Saxton

Located in Roanoke, Virginia, Maria Saxton holds a Ph.D. in Environmental Design and Planning from Virginia Tech. She works as an Environmental Planner and Housing Researcher for a local firm specializing in Community Planning, Architecture, Landscape Architecture, and Historic Preservation. Her dissertation explored the environmental impacts of small-scale homes. She serves as a volunteer board member for the Tiny Home Industry Association.