Documentation

Documentation for Go Carbon Free Metrics

Sections:

  1. My Impact Baseline
  2. Emissions Factors
  3. Action Estimates
  4. Points & Levels
  5. Individual Impact Comparisons

My Household Impact Baseline

To create the My Baseline Household Impact graph, we ask users to answer a few questions about their current activities and then create an estimate of their current greenhouse gas emissions (impact) for six areas:  Electricity Use, Home Heating (natural gas, fuel oil, propane), Gasoline consumption, air travel, red meat (ruminant) consumption and waste disposal.  We then track progress against this baseline as users take actions.  This is the progress bar in the My Progress section.

Some of these six categories of greenhouse gas emissions (GHGs) also contribute to air pollution emissions and other health hazards.  For the purposes of the My Baseline Household Impact graph, only the GHG emissions are represented in the values, measured as tons CO2e (carbon dioxide equivalent).  Other impacts will be measured in separate metrics and added to the site soon.

Each of these categories results in emissions of Greenhouse Gases that are identifiable and easily measurable with a body of research backing the data.  They are also categories with viable, actionable and generally affordable options for individuals to take.  Other impacts, such as the GHG emissions from the production of goods and services we purchase, are harder to track, identify and quantify, particularly with regards to the availability of reliable data on purchasing options to reduce impact.  We will add these into our calculations as good metrics become available.  We include them in the action set, just not in the metrics tracked.

What are GHGs?  GHGs are Greenhouse Gas emissions.  They arise from a number of different human activities, primarily from the burning of fossil fuels (coal, oil & natural gas), but also from animal agriculture, waste disposal and other activities.  The primary Greenhouse gas is Carbon Dioxide (CO2), other GHGs include methane (CH4), nitrous oxide (N20) and fluorinated gases.  These gases trap sunlight as it comes into our atmosphere and keep it from leaving which warms our climate (like adding a blanked).  To learn more about GHGs, visit the U.S. National Climate Assessment report.

Emissions Factors

Emissions factors provide information on the impact (GHG emissions) from a specific action based on a unit of measurement like a gallon of gas or kWh of electricity.  These emissions factors are used to estimate the My Impact Baseline for users based on the information provided in the My Energy Profile.  For all emissions factors we use a life-cycle number, which means we include the full impact of each source of emissions.  For example, for gallons of gasoline we include the emissions from burning the gas when driving your car as well as the emissions generated from the extraction of the gas at the well and delivery to the gas pump.  This provides a more complete estimate of the impact from each action.  Below are details and sources for each emissions factor used.

Electricity

Electricity emissions factors vary for each utility.  We enter the utility carbon intensity (GHG emissions) factor per kWh for each utility based on the best information available.  In some cases where the utility carbon intensity information is not available or the utility has a small service territory under our general site (not for custom city sites), we use EPA’s regional emissions factors.

Home Heating

Natural Gas

The life cycle emissions factor for Natural Gas = 17.44 lbs CO2e/therm. Source:  GREET model from U.S. Argonne National Laboratory (Burnham et. Al 2011)

Propane

The life cycle emissions factor for Propane = 16.5 lbs CO2e/gallon.  Source:  Tong et al. 2015.

Fuel Oil

The life cycle emissions factor for Fuel Oil = 27.3 lbs CO2e/gallon.  Source:  Tong et al. 2015.

Gasoline

The life cycle emissions factor for Gasoline = 26.9 lbs CO2e/gallon.  Source:  U.S. Life Cycle GHG Petroleum 2016, U.S. Department of Energy, National Energy Technology Laboratory, University of Calgary & Stanford University.

Airline travel

Aircraft use fossil fuels, like cars, so there is a direct impact for every gallon of aircraft fuel burned as well as the standard upstream emissions for fuel extraction and delivery.  However, air travel has an additional impact to warming due to the fuel being burned at a higher altitude.  This high-altitude factor increases the impact of emissions.  There is variation in estimates of the high-altitude impact ranging from just under 2x direct emission to over 3x direction emissions (Sausen et al 2005, IPCC 1999).  We use a factor of 2x to include both upstream and high altitude emissions factors as recommended by Kammen & Jones, 2011.  (Upstream emissions are approximately 20% of direct emissions).  Here is the calculation:

According to the U.S. Energy Information Administration (EIA):

The average passenger miles per gallon in 2016 = 53 mpg which equals .0189 gallons/passenger mile

The direct emissions for Jet Fuel = 21.1 lbs CO2/gallon

Direct emissions = .399 lbs CO2/passenger mile (.0189 x 21.1)

Adding in upstream and radiative forcing (high altitude impact) by multiplying by a factor of 2 = .798 lbs CO2/passenger mile

We round to .8 lbs CO2/passenger mile for the model

Note:  There is some variation in the impact per mile depending on the distance of the flight.  Aircraft use more fuel during takeoff and landing, so the longer the flight, the less fuel used per mile overall.  However, we are using an average number for simplicity and to reduce the data entry requirements for users.

Waste

From the U.S. Environmental Protection Agency (EPA) WARM model, the emissions for solid waste = .58 metric tons CO2e/ton of MSW (Municipal solid waste) (Kammen & Jones, 2017, EPA WARM model)

Food

We include consumption of red meat from ruminants, animals that create methane during digestion (beef, sheep and veal).  This is the diet category with the highest emissions profile.

The emissions factor for beef is 26.45 lbs CO2e/lb beef.  Emissions per meal based on 1/3 lb of beef per meal = 8.82 lbs CO2e/meal.   Source: Heller & Keoliean, 2014, supporting materials

Action estimates

To create the estimates on impact reductions and savings from individual actions, we use a combination of:  input from users in My Energy Profile, additional questions asked on the action page specific to that action (such as the number of light bulbs to be replaced) and additional factors specific to each action.

For example: for the Take the Train or Subway action – users input the number of miles per week they will be riding the subway and the miles per gallon rating of the car they are leaving at home.  From this we can calculate how much gasoline they will save and then use the Gasoline emissions factor to estimate the reduction in emissions.  The annual savings number is calculated using the estimated gallons of gas saved multiplied by an estimate of local average gas prices.

For Energy Efficiency and Home Energy actions we disaggregate the information from My Energy Profile to create a model of home energy use including metrics for heating, cooling, water heating, etc.  If the user chooses to estimate home energy use (as opposed to entering actual usage data for electricity, natural gas, etc.), then we provide estimates based on local average energy use for a typical household in that area and the answers to the estimator questions.  We use the results to estimate reductions from actions.

The impact and savings numbers are estimates driven by the accuracy of the data provided by users, the simplicity of the user input (to encourage participation) and available external data sets.  We will continue to enhance and update analytics in the future including refinement of current estimates, additional data points and new data features.

Points & Levels

Points

And now for the important part – the points!  The points represent the positive impact of taking an action.  For most actions the points are based solely on reductions of GHG emissions or water use.  Specifically, 1 point = 1 lb. of CO2 or 10 gallons of water reduced per year.  There are a few actions where it is difficult to track the impact directly, for these actions, points are assigned.  These include:  Buying Local/Organic, Participating in Demand Response, Install a Home Battery and all the Community Section actions.

Bonus Points

There are some additional bonus points for a few actions that are very important to reducing GHG emissions.  These actions either help create more renewable, clean energy or the infrastructure and technology we need to use more renewable energy.  The bonus points are added on top of the points received for the direct reduction impact from each action (which is generally high!). 

       Bonus Points             Action

2000                   Choose Green Electricity

2000                   Install Solar Panels

2000                   Buy or Lease an electric vehicle

1000                   Upgrade from gas/fuel oil home heating to electric heat pump heating

1000                   Upgrading from a gas/fuel oil water heater to electric heat pump water heater

1000                   Install a Solar Hot Water heater

  500                   Upgrade from a gas stove/oven to efficient electric stove/oven

  500                   Upgrade from a gas clothes dryer to efficient electric clothes dryer

Levels

Levels are created by benchmarking users to the average individual impact in their local area.  For each region or city, we estimate the average impact per person (GHG emissions in CO2e/year) for that area based on the average local energy use, waste, etc. (following the 6 categories used for individual impact).  As users go below this average, they go up in level.  Each level represents a 20% reduction below average.  If a user is above average, they are at the lowest level and stay there until they reduce to below the average.

Individual Impact Comparisons

To provide some perspective and raise awareness of differing impacts from households around the world, we provide a graph that compares average impact (GHG emissions in tons CO2e) at the household, city and US level as well as for a few other countries including the UK, China and India.  These estimates are constructed by tracking the same 6 areas tracked for users for a typical (average) household in each of these areas.

For example, to construct the US average number, we input the average household electricity use, natural gas (and fuel oil/propane) use, vehicles miles traveled, airline miles, garbage disposal and meals with beef (and lamb/sheep).  Then we multiple these numbers by the emissions factors above.  This creates an average impact for a typical (average) household in the U.S.  We then divide by 2.58, the average number of people per household to get an individual average impact.

For the other countries listed of the UK, China and India, we do the same and construct an average household profile and conversion metrics based on the best available information on household consumption and emissions.

For the My House estimate, we take the total impact result from the My Energy profile for the users household and divide by the number of people reported in the household to create an individual metric.

Note:  the My Baseline Average Household Impact per person is different from country level per capita emissions metrics publish widely.  Per capita emissions figures are created by taking the total emissions of a country from all sectors (household, industry, government, etc.) and dividing by the population.  This attributes all country emissions to individuals.  The metric we create only tracks emissions generated from household activities.

Below is a list of the references for the information used to create the individual impact stats.

United States

U.S. Energy Information Administration (EIA), home electricity use:  https://www.eia.gov/tools/faqs/faq.php?id=97&t=3

U.S. Environmental Protection Agency (EPA), GHG emissions factors:  https://www.epa.gov/sites/production/files/2015-11/documents/emission-factors_nov_2015.pdf

EIA natural gas annual:  https://www.eia.gov/naturalgas/annual/

EIA winter fuels outlook:  https://www.eia.gov/outlooks/steo/report/winterfuels.php

EIA:  heating oil use:  https://www.eia.gov/energyexplained/index.cfm?page=heating_oil_use

U.S. Department of Transportation, National Household Travel Survey 2009:  http://nhts.ornl.gov/2009/pub/stt.pdf

Jones & Kammen, A Consumption Based Greenhouse Gas Inventory of San Francisco Bay Area Neighborhoods, Cities and Counties:  https://escholarship.org/uc/item/2sn7m83z

EPA, Advancing Sustainable Materials Management, 2014 Factsheet: https://www.epa.gov/sites/production/files/2016-11/documents/2014_smmfactsheet_508.pdf

Organization for Economic Co-operation and Development (OECD): (source also used for China and India) https://data.oecd.org/agroutput/meat-consumption.htm

United Kingdom

UK.gov, Digest of UK Energy Statistics:  https://www.gov.uk/government/statistics/digest-of-uk-energy-statistics-dukes-2017-main-report

UK.gov, Annual Energy Use Statistics:  https://www.gov.uk/government/statistical-data-sets/annual-domestic-energy-price-statistics

UK.gov, Greenhouse Gas reporting Conversion Factors 2016: https://www.gov.uk/government/publications/greenhouse-gas-reporting-conversion-factors-2016

UK.gov National Travel Survey 2016: https://www.gov.uk/government/statistics/national-travel-survey-2016

UK.gov Statistics on Waste:  https://www.gov.uk/government/statistics/uk-waste-data

Agriculture and Horticulture Development Board, UK Yearbook 2017 Cattle:  http://beefandlamb.ahdb.org.uk/wp-content/uploads/2017/07/UK-Yearbook-2017-Cattle.pdf

China

Government of China, China Statistical Yearbook:  http://www.stats.gov.cn/tjsj/ndsj/2017/indexeh.htm

Jiansheng, et. al, A Comparison of Household Carbon Emissions Patters of Urban and Rural China over the 17 Year Period (1995-2011): http://www.mdpi.com/1996-1073/8/9/10537

International Air Travel Association, The shape of air travel markets over the next 20 years (source also used for China): https://www.iata.org/whatwedo/Documents/economics/20yearsForecast-GAD2014-Athens-Nov2014-BP.pdf

India

Residential Electricity Consumption in India, Prayas Energy Group: http://www.prayaspune.org/peg/publications/item/331-residential-electricity-consumption-in-india-what-do-we-know.html

Government of India, Ministry of Environment, Forest and Climate Change, First Biennial Update Report to the United Nations Framework Convention on Climate Change, 2015, http://unfccc.int/resource/docs/natc/indbur1.pdf

Stephane de la Rue du Can, et. al, LBNL, 2009, Residential and Transport Energy Use in India: Past Trend and Future Outlook http://re.indiaenvironmentportal.org.in/files/LBNL-1753E.pdf

EIA, Issues in International Energy Consumption Analysis: Electricity Usage in India’s Housing Sector, 2014:  https://www.eia.gov/analysis/studies/international/consumption/

U.S. Office of Energy Efficiency and Renewable Energy, Vehicles per Capita: Other Regions/Countries compared to the United States, 2017:  https://energy.gov/eere/vehicles/fact-962-january-30-2017-vehicles-capita-other-regionscountries-compared-united-states

Bansal, et. al, Indian Vehicle Ownership and Travel Behaviors: A Case Study of Bangalore, Delhi and Koldata, 2016: http://www.caee.utexas.edu/prof/kockelman/public_html/TRB17IndianTravelBehavior.pdf