Article Web Exclusive Yvonne HunterDana Papke Waters

Carbon Calculators: Definitions and Related Resources

Read the companion article entitled “Calculating Carbon Emissions“.

Yvonne Hunter is program director of the Institute for Local Government’s California Climate Action Network and can be reached at Dana Papke Waters is an air pollution specialist with the Climate Action and Research Planning, Research Division of the California Air Resources Board and can be reached at

Resources for more information

Cool California –  and

California Climate Action Network (CCAN) –

Definitions of common terms 

Greenhouse gas emissions are measured in pounds, metric tons, or, for larger measurements, in million metric tons (MMT) of carbon dioxide equivalent (CO2e) over some period of time (a year, for example).

carbon footprint is the measurement of total greenhouse gas emissions directly and indirectly contributed by a person, household, business, facility, or community over the course of a year. It takes into account greenhouse gas emissions from stationary combustion of fuel in a fixed location, mobile combustion of fuels from transportation sources and off-road equipment, process emissions from physical or chemical processing, fugitive emissions that are not physically controlled, and indirect emissions from electricity usage. A life-cycle approach to measuring a carbon footprint also estimates cradle-to-cradle greenhouse gas emissions associated with food choices and goods and services such as clothing, furniture and appliances.

carbon calculator estimates carbon footprints. It measures greenhouse gas emissions for a snapshot in time. Carbon calculators are used to calculate greenhouse gas inventories of facilities or operations in order to determine the amount of greenhouse gases produced for a specified year. The results can be used to prepare plans for actions to reduce the amount of greenhouse gas emitted annually or by a target year.

Being carbon neutral, or having a net zero carbon footprint, refers to achieving net zero carbon emissions by balancing a measured amount of carbon released with an equivalent amount reduced, sequestered or offset emissions.

Greenhouse gas (GHG) emissions are those gaseous constituents of the atmosphere, both natural and anthropogenic (caused by human activity), that absorb and emit radiation at specific wavelengths within the spectrum of thermal infrared radiation emitted by the Earth’s surface, the atmosphere itself, and by clouds. This property causes the “greenhouse effect.” Water vapor (H2O), carbon dioxide (CO2), nitrous oxide (N2O), methane (CH4) and ozone (O3) are the primary greenhouse gases in the Earth’s atmosphere. Moreover, there are a number of entirely human-made greenhouse gases in the atmosphere, such as the halocarbons and other chlorine- and bromine-containing substances. Still other greenhouse gases are sulphur hexafluoride (SF6), hydrofluorocarbons (HFCs) and perfluorocarbons (PFCs). (Source: Intergovernmental Panel on Climate Change)

Modeling tools estimate greenhouse gas emissions and potential reductions for various scenarios. They are typically used for climate action planning.

Protocols provide a standardized set of guidelines, methodologies and calculations to quantify and report greenhouse gas emission inventories.

The Climate Registry offers an online reporting tool to report greenhouse gas emission inventories. The report is third-party certified and the public can review verified greenhouse gas emission reports.

Carbon Calculators for Local Governments

Although the field is evolving, new tools are emerging to make the process of calculating carbon emissions from one’s home, business trip or city hall easier and more accurate. The following provides an overview to help understand the growing field of carbon calculators and carbon footprints.

Climate Registry Information System (CRIS) – from The Climate Registry

Several cities and counties have historically used the California Climate Action Registry’s On-Line Tool (CARROT) to calculate and report greenhouse gas emissions. However, the California Climate Action Registry is no longer registering greenhouse gas emission inventories. The California Climate Action Registry formed The Climate Registry, which offers the next generation of online reporting through The Climate Registry Information System (CRIS). Cities and counties can use CRIS to report their greenhouse gas emission inventories, which is third-party certified and available for public review.

Clean Air and Climate Protection (CACP) Software 2009

Local governments can use the Clean Air and Climate Protection (CACP) software to determine greenhouse gas emissions and criteria pollutants from government operations and communities. CACP is a downloadable spreadsheet, which ICLEI – Local Governments for Sustainability members can use to input aggregate information about energy usage, waste generation, and vehicle miles traveled (VMT) to calculate a greenhouse gas emission inventory. CACP was updated in April of 2009 to include the calculation methods of the Local Government Operations Protocol (LGOP), adopted in 2008 by the California Air Resources Board. 

Local Government Operations Protocol

Since both the Climate Registry Information System and Clean Air and Climate Protection calculators require a membership fee, some local governments may be interested in calculating their own greenhouse gas emission inventories. The Local Government Operations Protocol (LGOP) provides a standardized set of guidelines, methodologies and calculations for local governments to quantify and report greenhouse gas emission inventories from municipal operations. While there is not a calculator for the LGOP, it provides the option for a ‘free’ method to calculate greenhouse gas emissions from municipal operations.

Other Resources

Greenhouse Gas Equivalencies Calculator

This calculator, developed by the U.S. Climate Technology Cooperation, expresses quantities of greenhouse gases in terms of metrics such as number of cars, gallons of gasoline, acres of forest, and others.

Recycled Content (ReCon) Tool

The Recycled Content (ReCon) Tool calculates greenhouse gas emissions and energy consumption resulting from purchasing recycled products. For example, the tool estimates the greenhouse gas emissions and energy benefits of purchasing office paper with 35 percent recycled content instead of 25 percent recycled content…

WAste Reduction Model (WARM)

The WAste Reduction Model (WARM) calculates and totals greenhouse gas emissions of baseline and alternative waste management practices—source reduction, recycling, combustion, composting, and landfilling.

Center for Urban Forest Research (CUFR) Tree Carbon Calculator

The CUFR Tree Carbon Calculator for California climate regions produces carbon storage and sequestration values for a tree plus the associated energy conservation and emission reductions. The CUFR Tree Carbon Calculator is the only tool approved by the California Climate Action Registry’s Urban Forest Project Reporting Protocol for quantifying carbon dioxide sequestration from tree planting projects.

Energy Star Portfolio Manager

Portfolio Manager is an interactive energy management tool that allows users to create an inventory of greenhouse gas emissions from public buildings, set efficiency investment priorities, identify under-performing buildings, verify efficiency improvements, and receive EPA recognition for superior energy performance.

Portfolio Manager generates a Statement of Energy Performance for each building, summarizing important energy information including carbon emissions.

Household Carbon Footprint Calculators

There are many different household carbon footprint calculators available to help individuals gain a better understanding of the greenhouse gas emissions related to personal choices made on a daily basis. The Cool California Carbon Footprint calculator takes a life-cycle approach to measuring carbon footprints, including direct and indirect greenhouse gas emissions from transportation, household energy, food, goods and services. The calculator also acts as a benchmarking tool where individuals can compare their results to typical households in their city or region and the U.S. or global average.

General Information

ICLEI – Local Governments for Sustainability
The Climate Registry
Local Government Commission
Flex Your Power

This article appears in the July 2009 issue of Western City
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