The EVO Tree looks simple, but it is based on the integration of several complex data models used to assess the wide range of impacts we have on the environment. The EVO tree asks you a series of questions and based on your answers will show you how “green” you are in different areas of your life relative to the average American. Each question relates to a specific action — from the kinds of goods you purchase to how far you drive to work. The EVO Tree is not a calculator, so it does not tabulate your answers and give you a hard and fast “green score.” Instead, it associates CO2, Land, Water and Pollution impacts to specific actions in order to illustrate how different choices directly affect your Total Environmental Impact (TEI).

 

The leaf color ranks your answer. A Green leaf says that you’re making a good choice that does minimal or no harm to the environment. By contrast, an Orange leaf means your action was less than environmentally friendly. A Yellow leaf reflects the actions of an “average American.” Data for the average American is derived from numerous openly published sources, including Redefining Progress and the Global Footprint Network, the Union of Concerned Scientists, the Energy Information Administration, the Environmental Protection Agency, the U.S. Department of Agriculture, and many more. Here’s a complete list of sources and a detailed explanation of how EVO defines Total Environmental Impact

 

The dark green leaf correlates to a value that represents the best, reasonable answer for a given consumption category - for instance waste: even though it is possible that an individual could have absolutely no waste, we assume the dark green answer to be 1 lb of trash, versus the average American’s 34 lbs per week. The range of values that apply to the other three leaf colors - light green, medium green, and orange are determined by a curve between 1 lb and 34 lbs. See an example of how leaf colors are assigned to specific answers.

 

The number of leaves that appear on your EVO Tree after you answer a question is determined by the “efficacy” of that question to reduce your overall impact. This is calculated as a ratio between the best (dark green) answer over the average (yellow) answer, which is then applied to the Total Environmental Impact of a specific consumption category.

 

An action with a small but still significant impact - for example recycling old shoes — affects 1% or less of your TEI and so receives one leaf. An action with a very large impact - such as the fuel efficiency of your car - is more than 15% of your TEI and so receives six leaves. In the example above, the efficacy is 97% (1lb/34 lbs) which is then multiplied by that category’s TEI %. In the case of waste, the TEI % ends up being 2.7%. So it receives 3 leaves (rounded up).

 

You can learn more about the EVO tree application with lots of illustrations on the GreenDig website.