Carbon Calculating: Estimating Your Home Energy Impact

Carbon Calculating: Estimating Your Home Energy Impact

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The dozens of carbon calculators obtainable as apps and on the net present broadly divergent estimates of your carbon footprint. Whether you select to make use of one of many many calculators or wish to assemble your personal estimate — from discovering and understanding your private home power utilization to assessing a carbon calculator’s outcomes — this text will break down methods to monitor the impression of residence electrical energy, pure fuel, gas oil, or propane use.

As talked about within the first article in this series, carbon calculators use completely different formulation and estimated CO2 emissions. We entered the identical information in 5 web-based carbon calculators and acquired strikingly completely different whole emissions estimates, in addition to radically completely different shares of the entire carbon footprint attributed to residence power use. The variations increase vital considerations concerning the accuracy of every of the calculators.

Earth911 in contrast six web-based carbon calculator estimates of residence power emissions, proven right here in comparison with the entire carbon footprint reported for the family. Karma Wallet doesn’t get away the power whole. (Click for a bigger picture.)

Each calculator we examined has strengths and weaknesses. The actuality is that you’ll most likely want to make use of elements of a number of calculators to get probably the most correct cumulative carbon footprint in your family. Before we discover which of them supply probably the most reliable residence power estimates, let’s stroll by way of the data it is advisable have at hand.

If you’re a DIYer,  you will see the formulation for making your personal calculations on the finish of this text.

Collecting the Data

To get began, discover your utility payments that will help you decide your private home power use. Try to gather a full yr’s price of your electrical payments in addition to different power payments, comparable to fossil gas, pure fuel, gas oil, or propane. Carbon calculators ask for this data by month or as an annual whole.


Your electrical energy invoice presents energy consumption in kilowatt-hours, which symbolize the quantity off watts of power wanted to energy a 1,000-watt microwave oven for an hour, for instance. Look for “kWh” in your electrical energy payments, add up a yr’s price of payments to reach on the annual whole, then divide by 12 to get your month-to-month common electrical energy consumption. Whether the calculator you utilize asks for month-to-month or annual kilowatt-hours, you’re prepared.

Most carbon calculators ask for electrical information in kWh, however you may additionally discover calculators that ask in your month-to-month or annual spending on electrical energy. Based on our expertise, spending is a much less dependable strategy to estimate electrical energy utilization than precise utilization based mostly on kWh as a result of native charges fluctuate. Calculators that use spending should apply guesswork to estimate your utilization.

In addition to your electrical energy utilization, the supply of your energy makes an enormous distinction to your environmental impression. If you get a big share of renewable sources, comparable to hydro-electric, photo voltaic, or wind, the power footprint is decrease than somebody who depends on fossil gas era.

Only two of the calculators we used, Doconomy and the EPA’s, requested about use of renewable power. However, Doconomy asks solely when you’ve got renewable power, not the share of electrical energy that’s renewable, allocating CO2 emissions based mostly on the idea you both have entry to all-renewable or no renewable power.  A easy sure/no query doesn’t cope with our realities. The EPA calculator, then again, asks you to enter the precise share, which we advocate to make sure you get an correct emissions report.

Local renewable percentages rely in your utility’s selections about methods to generate or the place they purchase power. For instance, the place we reside, in Western Washington, Pierce County enjoys 89% renewable power whereas in Eastern Washington, Whitman County will get solely 41% of its energy from renewables. But statewide, the everyday resident’s renewable power share is 85% as a result of a lot of the inhabitants lives on the western aspect of the state, the place renewables dominate.

Many utilities will listing the share of renewable power you obtain in your invoice or in an annual buyer report. If you don’t know your native renewable share, the U.S. Energy Information Administration provides state-level information about electrical power sourcing. Click in your state and select the Electricity tab within the state report. You must do a little bit of math to calculate your renewable share by mousing over the bar within the chart seen under to get the information about all of your energy sources.

Net Electricity Generated by Source chart from EIA
The EIA’s state-level information can be utilized to estimate a renewable power share to be used in a carbon calculator.

Natural Gas

Methane fuel, or “pure fuel,” consumption is offered in a number of completely different items together with therms (every therm equals 100,000 British thermal items, the equal of warmth created by 29.3072 kWh of electrical energy), “ccf,” which represents lots of of cubic ft of fuel delivered monthly, and “mcf,” which counts cubic ft by 1000’s.

You might have to convert ccf into mcf, or vice versa, to make use of a selected calculator — take note of the unit of measure requested as a result of getting into your fuel utilization within the flawed unit can throw your impression outcomes off by an element of ten. To convert ccf into mcf, divide by your whole ccf by 10; going the opposite means, multiply your mcf by 10 to get whole ccf.

Fuel Oil

Burning oil to generate heat in the home has been on the decline because the oil disaster of the Nineteen Seventies. But a number of states nonetheless see vital use of oil, together with the highest 5 (so as): New York, Massachusetts, Pennsylvania, Maine, and Connecticut.

You will enter your gas oil utilization in gallons or by the greenback quantity you spend — that information will probably be proven in your invoice. Add up a yr’s price of payments and divide the entire by 12 to get a mean month-to-month gas oil utilization to make use of in your calculation. And as a result of native charges fluctuate, we advocate utilizing the precise quantity of oil and never the month-to-month spending for extra correct outcomes.


This type of fuel, which differs from methane chemically, remains to be in use in tens of hundreds of thousands of houses within the U.S. All the carbon calculators we examined that included propane as an possibility requested both a month-to-month or annual quantity in gallons.

The Calculators

For this text, we targeted on calculators supplied on web sites, however app-based calculators behave in related methods. In the ultimate article on this collection, we are going to current a evaluation of all of the app and internet calculators examined.

Environmental Protection Agency Carbon Calculator

Energy estimate: A-
Total footprint estimate: D-

The EPA Carbon Calculator requested for probably the most data, together with the share of renewable power in your house’s electrical energy provide, to estimate energy-related emissions. The renewable power information we entered clearly diminished the entire power footprint estimate for our three-person family. When we in contrast the EPA’s power outcomes to our guide calculation, it was the closest estimate acquired, adopted by the Wren calculator. Unfortunately, the EPA calculator doesn’t cowl all of the classes of emissions needed to offer a complete footprint estimate.

Because it doesn’t cowl all of the methods we generated emissions, providing estimates just for residence heating and power, driving, and the impression of recycling selections, the EPA calculator doesn’t assist people make many choices that might cut back their environmental impression. It misses too many emissions.

CoolClimate Network

Energy estimate: C+
Total footprint estimate: B+

A undertaking of the University of California, Apple, Meta, and the Nature Conservancy, the CoolClimate Household Impact Calculator supplies probably the most detailed evaluation of all facets family carbon impacts on this evaluation. While the house power estimate consists of entries for variety of folks within the family, share of renewable power used, and volume-based entries for electrical energy and pure fuel use, the estimated footprint for our residence power was clearly too low, representing solely a 3rd of the emissions truly generated.

The CoolClimate calculator does a fantastic job by offering many detailed entries for air journey; quantity and sort of autos pushed; meat, dairy, and fish consumption; and spending on items and companies, for instance. However, it additionally inserts arbitrary assumptions that can not be adjusted for annual development, furnishings, and clothes spending that added 15% to our estimated whole footprint. If these entries have been customizable, the calculator could be even higher.

Another shortcoming is an absence of a clearly outlined methodology. CoolClimate factors to a analysis paper that explains how fashions can predict carbon emissions however doesn’t handle how the estimate is generated. Note that this calculator asks for fuel utilization in cubic ft, not ccf or mcf. If your invoice supplies utilization data in ccf, multiply by ten earlier than you enter your information; in case your invoice shows mcf, multiply by 100.


Energy estimate: D-
Total footprint estimate: D+

In the primary article on this collection, we identified that calculators tied to the sale of carbon offsets usually make considerably greater estimates than calculators that don’t supply offsets. TerraPass’ Individual Calculator outcomes don’t clarify sense in two methods. Based on the identical information we entered within the different calculators, TerraPass presents a complete footprint that’s virtually twice the quantity of the following highest estimate. Compounding our confusion, the TerraPass energy-related outcomes account for 90.2% of the entire emissions — residence power utilization ought to fairly be half or much less of a complete carbon footprint.

TerraPass doesn’t account to be used of renewable power. And just like the EPA calculator, TerraPass doesn’t accumulate any meals, purchasing, or companies information, that are important to understanding your whole footprint. On the opposite hand, the TerraPass estimates for driving and air journey are stable. They ask for particular details about what sort of automobiles you drive and the variety of size of flights you are taking yearly to ship largely correct estimate of journey impacts.


Energy estimate: D
Total footprint estimate: F

Doconomy and the United Nations partnered to create a European focused carbon calculator that covers a variety of family impacts, together with power, driving, air journey, meals, and purchasing selections, in addition to the emissions created by the companies you utilize. However, each facet of the software produced surprisingly low emissions estimates. For instance, Doconomy estimated that our annual residence power impression is simply 3,840 lbs., and our food-related emissions solely 540 lbs. That’s clearly incorrect and leads to a really low estimate in comparison with the opposite calculators and our guide estimate of emissions. The low estimate might make you are feeling higher about your self, however you’ll be unprepared to make modifications that decrease your impression.

As famous within the dialogue of electrical energy, Doconomy asks whether or not you purchase renewable power, treating your sure or no reply as representing 100% of the facility used, in keeping with its published methodology. Except for a house that depends solely on its photo voltaic or wind era capability, Doconomy’s assumption about renewable power shouldn’t be relevant to anybody related to the grid. One optimistic: Doconomy sells offsets however delivered the bottom estimated total footprint among the many offset distributors reviewed on this article. We’d wish to see them refine and enhance the formulation and assumptions that drive their outcomes.


Energy estimate: B-
Total footprint estimate: C

Another carbon offset vendor, the Wren carbon calculator supplies one of the crucial complete evaluation of a family’s carbon impression. In addition to residence power estimates, Wren calculates driving and air journey emissions, in addition to meals (together with pet meals), purchasing, and companies impacts. The web site’s whole annual estimate was the third highest, however way more conservative than TerraPass and Karma Wallet. However, Wren doesn’t publish its methodology, so it’s tough to validate its estimates. Its residence power estimate is predicated partially on the ZIP code entered. In our case, including the ZIP code lowered our estimated impression by 31.6%.

Karma Wallet

Energy estimate: F
Total footprint estimate: D+

The Karma Wallet calculator takes a totally completely different strategy than the manual-entry calculators above. It analyzes your spending by monitoring bank card and financial institution transactions. As we’ve famous about spending-based estimates, it’s unattainable to extrapolate with helpful precision the quantity of electrical energy, pure fuel, or different items of power used from the value paid with out in depth context. Karma Wallet doesn’t get away the person classes of emissions, offering solely a complete emissions estimate. Our Karma Wallet outcomes have been 23.2% greater than the typical reported by all the opposite calculators reviewed right here.

Karma Wallet affords two strategy to take motion. It suggests options to your present spending, comparable to switching from one wi-fi service to a different (with cashback affords), and supplies offsets for buy. The steerage about selecting extra environmentally accountable corporations to purchase from could be helpful if the precise impression of these selections was clearly offered, however the software solely compares a sustainability score with out explaining how a change reduces carbon emissions. This probably great tool requires the person to take an excessive amount of on religion as a result of there isn’t any quantitative information about classes of your present carbon impression or how making modifications will cut back emissions.

The DIY Way

Checking the work of third-party calculators can assist you make assured selections. But we all know doing the maths isn’t everybody’s cup of tea. If you’d love to do your personal estimates, listed here are easy formulation for calculating the sources of every of the main kinds of residence power. For instance, when calculating a carbon footprint for a house that makes use of electrical energy and pure fuel, you’ll want so as to add the totals for all of the power sources to reach your cumulative residence power footprint.

We’ve offered common emissions components for every sort of power based on the EPA’s reporting. Keep in thoughts that native components, such because the situation of your furnace and particular sources of fuel, oil, or renewable power have an effect on your precise impression. Alas, estimates are usually not actuality. We advocate asking your native utility for the emissions factors of their power sources to enhance your estimate.

Electricity, No Renewable Sources

Depending on what your utility burns to generate electrical energy, the emissions will fluctuate. Here are formulation for 3 frequent fuels used to generate electrical energy in business crops.

The EPA stories the emissions components for flamable fuels in hundreds of thousands of British Thermal Units (mmBtus). We included a step to transform the hours reported in your electrical invoice  into the equal mmBtus, which entails multiplying the variety of kWh by 0.0034095106405145. The EPA additionally supplies emissions components per mmBtus are offered in kilograms, so the ultimate step, multiplying the outcome by 2.2046, converts the end in kilograms to imperial kilos. If the U.S. would embraced the metric system, this might be simpler. When utilizing a calculator, enter the values in BOLD under.

Mixed Coal

The power business usually makes use of blended coal, which has an emissions issue of 95.52 kg per mmBtu, to energy electrical energy era crops. The formulation to seek out your private home’s power emissions is:

CO2 emissions (in lbs.) = (YOUR TOTAL ANNUAL kWh) * (0.0034095106405145 MMBtu/kWh) * (95.52 kg CO2/MMBtu) * 2.20462

Natural Gas

Many utilities burn pure fuel in peaker crops, which come on-line during times of excessive demand. But some utilities depend on pure fuel across the clock, accounting for 37% of all of the pure fuel burned within the U.S., about 11.27 trillion cubic ft in 2021, according to the EIA. If your utility sources most electrical energy from pure fuel, right here’s the calculation it is advisable carry out:

CO2 emissions (in lbs.) = (YOUR TOTAL ANNUAL kWh) * (0.0034095106405145 MMBtu/kWh) * (53.06 kg CO2/MMBtu) * 2.20462

Biomass or Landfill Gas

Capturing and burning gasses produced in landfills and from processing natural waste, typically known as biogas or renewable fuel, sounds fairly inexperienced. But burning fuels emit CO2, no matter the place they got here from. These gasses accounted for about 0.2% of utility-scale electrical energy era in 2021, according to the EIA. Here is the house power carbon footprint formulation for biogas:

CO2 emissions (in lbs.) = (YOUR TOTAL ANNUAL kWh) * (0.0034095106405145 MMBtu/kWh) * (52.07 kg CO2/MMBtu) * 2.20462

Electricity With Renewable Sources

The share of renewable power you utilize can change your whole power footprint considerably. To discover details about how a lot wind, photo voltaic, or hydroelectric energy your utility makes use of, together with the supply of the remainder of your power, discuss with the EIA website we talked about earlier. To discover your adjusted emissions based mostly on the combination of fossil gas and renewable power powering your private home, we add a step to the earlier fossil gas calculation (we use blended coal on this instance), highlighted under in italics:

CO2 emissions (in lbs.) = (YOUR TOTAL ANNUAL kWh) * (0.0034095106405145 MMBtu/kWh) * (95.52 kg CO2/MMBtu) * 2.20462 * 1 – (1 – YOUR RENEWABLE ENERGY PERCENTAGE EXPRESSED AS DECIMAL)

Fuel Oil

A gas oil furnace operates like an influence plant with no mechanism for changing the warmth into power — it’s heating your home, as a substitute. The formulation is much like the oil-fired electrical energy calculation above, and makes use of the CO2 emissions issue of 24.78 lbs. of CO2 per gallon:

Total CO2 emissions = YOUR ANNUAL OIL USE IN GALLONS * 24.76


Propane is simpler on the ambiance however nonetheless emits 12.68 lbs. of CO2 per gallon burned. To discover your propane carbon footprint:

Total CO2 emissions = YOUR ANNUAL PROPANE USE IN GALLONS * 24.76