The concept of the personal carbon footprint has become controversial – some see it as a distracting ploy to shift the focus of responsibility for carbon emissions away from industries and onto individuals.   

Others point out that the emission reductions that individuals can realize on their own are insignificant compared the potential actions needed to help our societies to transition to clean energy systems.  In this line of thinking for example, an individual choice to buy a Tesla or chose public transit means nothing compared, to say, mobilizing actions for the legal and policy changes to end the sale of new gas powered cars in a country.

But the process of assessing our emissions profile does help generate a greater awareness and understanding of climate issues.  With more focus and understanding we become better prepared empowered to press for the changes we need to transition away from fossil fuels.

That’s why, I thought it is was worthwhile to assess our own household carbon footprint.  I wanted to know how our profile ranked against averages and what are the most important factors that affect our emissions.  And if there are reasonable steps we can take to reduce our emissions, I want to know what they are.

There’s an app for that…

The first thing you learn when you set out to calculate your carbon footprint, is that there are dozens of sites that are all too happy to offer you the service of their free carbon footprint calculators.  

Most are offered by organizations that would like to then sell you voluntary carbon offsets – a credit representing carbon emissions that have been eliminated elsewhere – that you can purchase to cancel out your own emissions.

The problem is that calculators use very broad estimates to calculate a household’s emissions.  A typical calculator might ask, for example, how much money your household spends on energy generally within a year.  It then applies an average energy emissions rate for the average blend of energy used for the country or region in which you live.

But it makes a big difference if your household “energy spending” is on oil, gas or electricity.  Even within that – it make a big difference if your electricity come from a coal burning generating plant or a hydro-electric facility. 

To get a decent read on our household emissions, I had to ditch most of the convenient calculators.  Instead,  I take stock of our annual energy consumption by source – kilowatt hours of electricity, litres of natural gas, miles driven by car – and then look up the specific emission rates for those sources to calculate our emissions.

CO2 or CO2e

Another challenge that comes up when calculating one’s emissions is that some sources report on CO2 emissions and others report CO2 equivalent emissions or CO2e.

CO2 only measures carbon dioxide – the most prominent greenhouse gas affecting the environment.  CO2e stands for “carbon dioxide equivalent” and measures CO2 plus all other greenhouse gases including methane, nitrous oxide, and others, based on their global warming potential or GWP.  For example, scientists recognize that  1kg of methane causes 29.8 times more warming over a 100-year period compared to 1kg of CO2.  Methane therefore has a GWP of 29.8. 

An estimate of CO2e emission is more comprehensive because it includes all greenhouse gasses and provides a better view of the total environmental impact of our actions or choices. 

Unfortunately, not all sources report on a CO2e basis. In calculating our own household impact  I had to use a CO2 basis which is more commonly available.

Household Emission Categories

To get started in calculating our household emissions, I broke our activity down into four categories:

• Household energy use

• Transportation (cars)

• General purchases and consumption

• Air travel

It took a couple of hours to pull the information from our utility bills, check our mileage records, go through our other records, and figure out our activity by category.  I then looked up the emission rates for each activity or source.  At the end of it all, I had a nice-looking spreadsheet that was telling me what I wanted to know but was a little afraid to ask -that in 2022 my family of 4 emitted about 50.5 tonnes of CO2 – about 12.6 tonnes of CO2 per person.

A closer look at the sources of these emissions pointed to some steps we can take to cut back in the future.

Household Energy – 10.7 tonnes CO2

I was most afraid to ask what our emissions in this category would be because we operate two homes – our family home in the city as well as a cottage.

We heat our city home with natural gas and in 2022 we used nearly 5,000 cubic meters of gas.   According to the US Energy Information and Administration – 1,000 cubic feet of natural gas releases about 55 kg of CO2 on a “from the well to the tip of the burner” basis.

These are US averages, so I contacted my gas company Energir for more precise information about gas from their network.  (Energir, by the way, was formerly Gas Metropolitian – most fossil fuel companies are “rebranding” to be energy companies – which usually means dropping any mention of gas, oil or coal in their names).  

While some utilities provide information on the fuller scope of emissions resulting from the power they supply – it turns out that Energir does not.  And they did return my calls or emails on the subject.

So relying on the US averages –  I concluded that heating our home, our hot water, and using our gas oven and BBQ in 2022 produced 9.5 tonnes of CO2 emissions. 

Our cottage on the other hand is heated entirely by electricity.  In 2022 we used nearly 78 megawatt hours of electricity to heat and power our cottage as well as operate the lights and appliances in our city home.  That seemed like a lot of electricity – I was dreading the calculation of how much CO2 those 78 megawatts would represent.

Maybe I’m naive or maybe like many, I hadn’t spent much time thinking about emissions from different types of electricity-generating facilities, but I was happily surprised to find out that each megawatt hour of electricity delivered through my utility, Hydro Quebec, generates only 600 grams of CO2.

That means that in 2022, all of the electricity that we used at the cottage at our home in the city amounted to about 60 kg of CO2 – essentially 0 given household footprints are measured in tonnes.  While obvious now in retrospect, I realized what a great benefit it is that pretty much all electricity in Quebec is derived from hydroelectric facilities.  While hydropower can have other environmental impacts – it does not produce a material amount of greenhouse gasses.

To put this in perspective, if we were using the same amount of electricity but living in Alberta in 2020 (the most recent data available from Canada’s Energy Regulator ), our emissions from electricity use alone would have resulted in about 47 tonnes of CO2 equivalent emissions.  That’s because Alberta, Canada’s 3rd largest electricity producer, generates 89% of its electricity from fossil fuels – 36% from coal and 54% from natural gas generating plants.

If I learned anything from this exercise, it was the importance of converting all our electricity grids to clean sources of electricity such as wind, hydro, and solar, and to power as much as possible from this clean electricity to reduce emissions.

We also have a backup generator at our cottage that runs on propane.  In 2022 we used 673 liters of propane, which represents about 1 tonne of CO2 emissions, again using data from the US dept of Energy, 

All in all – the energy from our home and cottage produced 9.6 and 1.1 tonnes of CO2 respectively.

Transport – 4.9 tonnes of CO2

Our family owns two cars – a 2016 2.5l Subaru Outback and a 2021 Toyota Rav 4 Prime plug-in hybrid.  In 2022 we logged about 18,000 km on each vehicle.  Based on the fuel economy data for the Subaru, we used about 1,600 L of gasoline.  Each litre of gasoline burned generates 2.3 kg of CO2 so in using the Subaru, I estimate we emitted 3.7 tonnes of CO2.

Our plug-in hybrid has a much better emissions profile.  I figure that about half of the kilometers I drove in this car in 2022 were in “electric mode”, so zero emissions.  The other half of the mileage, in hybrid mode, used about 6L of gas per 100 km – about 30% better fuel efficiency than the Subaru.  I estimate we used 560 L of gas for the Toyota in 2022, which generates 1.3 tonnes of CO2.

All in all – for transport we emitted 4.9 tonnes of CO2 through our cars.

Consumption – 25 tonnes of CO2

Most of our emissions come from all the stuff we buy and consume. However, getting a reliable estimate of our carbon impact from the things we buy in a year is next to impossible.  One would have to build an inventory of all the items purchased by the household in a year.  Each item would also need an accurate estimate of the emissions created in its production and distribution.  Unfortunately, no one has that kind of information.

To assess our emissions in this category I had to rely on a publicly available calculator that estimates emissions based on the dollar value of annualized purchases.  While it was the only feasible approach I could find, the accuracy of emissions estimates is likely very suspect.  Based on dollar spending, the carbon intensity factors used in the calculator have to be very broad estimates.  They can’t for instance account for our family’s efforts to buy goods that are produced locally.  Even if we try and make more conscious choices in our purchases, the model cannot reflect that and it will only respond to the dollar amount spent.  

The one found at carbonfootprint.com seemed more robust than most because it at least allows users to input more refined household spending estimates across 14 different purchase categories.

With our household spending estimates, that model told me that our family generated 25 tonnes of CO2 emissions from purchases in 2022 – 6.2 tonnes per person.  Half of that comes from food purchases which can vary based on meat-eating habits – I had put us in the “medium meat eater” category.

While that is interesting to know.  More interesting is to know what we could do to reduce that. According to the model, the biggest thing that would make a difference would be to generally spend less money, particularly on food.  That does not seem really actionable.

The other big driver would be to eat less or no meat.  As family, we’re already cutting our meat consumption, but we’re not prepared to give it up entirely.

Air Travel – 10 tonnes of CO2

In 2022 people flocked back to airports in a wave of post-COVID revenge travel. Our household was no different.  My wife and I took several trips and one of my sons travels a lot to compete at international sporting events.  

Calculating emissions from flights is pretty straightforward and in this case, a calculator is pretty helpful.  Again, the one at carbonfootprint.com allowed for the most detailed inputs, estimating emissions between specific airports.   Using this calculator, the impact of the flights our family took in 2022, ended up at nearly 10 tonnes of CO2- about 20% of our total footprint.

Airplane emissions add up very quickly.  Planes burn a lot of fossil fuel and emit around 100 times more CO2 per hour than a shared bus or train ride.   In addition to that, they also provoke strong non-CO2 warming effects.  Plane engines produce vapor trails and trigger cloud formation which traps heat in the atmosphere.  Burning jet fuel in the atmosphere also produces other non-greenhouse gas emissions that interact with the ozone layer to further contribute to warming.

Studies show that these non-CO2 effects contribute twice as much to global warming as the CO2 effect so carbon calculators usually use a factor to double or triple the fossil fuel impact of air travel.

For long trips, there are not a lot of great alternatives to air travel – other than to reduce it.  If you do fly, direct flights are better than connecting flights and some airlines have better practices than others.  There is encouraging news about electric plane engines and alternative fuels that may become commercially available soon.  

Until then though, the most effective way to reduce air travel emissions is by flying less and/or by purchasing high-quality carbon offsets to neutralize the emissions impact of flying.

Now what?

At the end of the day, this exercise suggests that our family emitted over 50 tonnes of CO2 in 2022 – or 12.6 tonnes per person.  

While that is below the Canadian average, we can’t really applaud ourselves.  We should be well below the Canadian average because we live in Quebec – all of our electricity comes from hydropower –  a zero-emission source.  And Canada’s average is not great in the first place when compared to other G7 countries other than the US.

What can we do?  The process of calculating where our emissions come pointed to important steps we can take:

1. Eliminate natural gas use at home.  We should be taking full advantage of the clean electricity in our province to cut our household emissions.

Our furnace is aging and will need to be replaced – when we do that, we will look top replace it with a boiler system that run on electricity.  Same with our hot water heater.  

When we got our gas stove, we thought we were getting a dream appliance – it turns out that aside from our growing environmental concerns, in our experience a gas oven is terrible for baking and a gas stove burners pale in comparison to cooking with an induction range.  We’re also increasingly concerned of the health impact of burning gas inside the home.  Replacing our gas stove with an induction range is a no brainer for us.  We will be keeping the BBQ though.  

Making these changes could save us about 9.5 tonnes of CO2 per year.

2. Change our car.  We love our plug in hybrid.  We’d love to be driving full electric vehicles but given the kind of winter driving we do we require 4 wheel drive.  As reasonably affordable options come out, we will be looking to replace the Subaru with either a plug in hybrid of a fully electric model.  

Changing our cars would save 2.5 to 4 tonnes per year.

3. Air Travel.  We are privileged to live in a time when we can fly to different part of the world for both business and pleasure.  We’re not willing not give that up.  The good news is that technology exists today to power flights under 3 hours by battery and most expect zero emission technology to be developed for longer haul flights within the next ten years.    

Hopefully, the airline industry’s transition to zero emission technology will happen quickly.  Until then, our family will purchase carbon credits to offset the impact of all our flights.  They’re not that expensive, and if were are willing to spend money on travel, we can step up to spend a little more to reduce the emissions impact of the activity.

4. Buying offsets generally.  In addition to buying offsets for air travel, we can also buy offsets for our overall household emissions.  Buying high quality, verified carbon offsets is effective way to net out one’s carbon emissions.  

It is important to note though that offsets are no substitute for reducing emissions.  As a society we will never be able to offset our way to net zero – we need to fundamentally cut emissions.  Offsets, if they are verified and of high quality, can help address emissions that are more difficult to reduce. 

I plan to write separately about my research into the voluntary carbon offset market.  I found that a high-quality, verified credit to offset one tonne of CO2 cost between $15 and $30.  

For $1,200 I chose to offset my household’s entire 50 tonnes of emissions in 2022.  That cost works out to $300 per person.  I’m fortunate that taking on such an added expense is not a hardship.  

Moving forward, I will think of purchasing carbon offsets in the same way we think of charitable giving.   Both are about stepping up to contribute to the benefit of society.

At the end of it all,  I came away with a much better sense of the real drivers of our household emissions and in particular what we can and cannot control.  We came up with specific steps that we would be happy to take that could reduce our household footprint by about 25%.  And I came up with a way to neutralize the rest through voluntary credits.

Despite the pitfalls – it was a worthwhile exercise. ■