Reducing the carbon footprint of a building is not as difficult or expensive as one might think. But individual efforts will not be enough by themselves.
By John Loukidelis and Thomas Cassidy
Published September 08, 2020
Eric Holtaus, the meteorologist and activist, usually ends his tweets about severe weather events and disasters with the phrase "We are in a climate emergency." Holtaus has been quite open about his mental-health struggles, which he says relate to his anxiety about the climate crisis.
His anxiety is easy to understand. Many respected climate scientists like Kate Marvel point out that the science doesn't justify despair and that despair is a luxury only those of us in the rich world can indulge. Nevertheless, the climate challenge is daunting. Evidence piles up on evidence that we are rapidly running out of time, but business carries on largely as usual. (More on that below.)
What is the concerned citizen to do? This article explores one individual's efforts to reduce the carbon footprint associated with his home. Thomas Cassidy did it by "fuel switching": he removed the natural gas furnace and hot water heater in his home and replaced them with an air source heat pump and hybrid electric hot water heater. These changes reduced his home's estimated carbon footprint from heating by about 94 percent.
Thomas' experience shows that reducing the footprint of a building is not as difficult or expensive as one might think. The article also shows, however, that individual efforts won't be enough. By all means, do everything you can to limit your personal emissions.
But it won't be enough, if de facto climate change deniers - like the federal and Ontario Conservatives - completely undermine your work with pretend climate "policies" that only lead to more emissions growth.
According to the IPCC's special report released in October, 2018, to keep to "only" 1.5°C of warming, we will need to reduce greenhouse gas (GHG) emissions from 2010 levels by 45 percent by 2030 and then reach net-zero global anthropogenic GHG emissions by 2050. To prevent further warming after that, we will likely need industrial-scale CO2 removal to prevent the worst damage associated with emissions.
Wrestling this monster to the ground means we must reduce the emissions generated by our homes and buildings (among other things), especially in a cold climate country like ours. In 2018, Canada emitted a total of about 729.5 megatonnes (Mt) of CO2 equivalent (CO2e). Of that total, 92.5 Mt of CO2e, or about 12.68 percent, came from buildings.
Thomas lives in Hamilton, and the national emissions figures are skewed by the oil and gas industry, Canada's largest emitter, which is not a large source in Ontario.
Buildings, however, are a large source of emissions in Ontario. In 2017, the province emitted 159 Mt CO2e, and about 35 Mt (pdf at page 11) of this total (ie about 22 percent of it) came from heating and air-conditioning buildings.
For an individual living in Ontario, then, reducing the carbon footprint associated with heating his home seems like a good way to help reduce emissions.
Thomas lives in a house in southwest Hamilton that was built at the end of the 19th century. The house is semi-detached, has three bedrooms and a floor area of about 168 square metres (about 1,800 square feet). The attic has an area of about 56 square metres (about 600 square feet). The house's exterior walls have a total area of about 186 square metres (about 2,000 square feet). (As we'll see, this figure was important for analyzing the efficacy of insulation.) The walls are made of double brick and are not insulated.
Before he made any changes to his home, Thomas burned about 2,300 cubic metres of natural gas each year for heating and hot water. Burning a cubic metre of natural gas emits about 1.94 kg of CO2. Taking into account the upstream emissions associated with the extraction and delivery of natural gas in Ontario adds another 0.245 kg of CO2e for a total of about 2.2 kg of CO2e per cubic metre burned. As a result, heating Thomas' house and water with natural gas emitted the following amount of CO2e:
The foregoing might not fully account for fugitive emissions.
Of course, Thomas needed to live in a heated home. He also wanted to weigh his options. He needed some guiding principles and settled on the following.
He asked himself about the price he would be willing to pay per tonne of emissions avoided. Thomas did not have an unlimited amount of money to spend on his project, and so he imposed a kind of carbon tax on himself.
Thomas also considered the opportunity cost of his emissions reduction options. He could spend money on an option, or he could spend that same money on something else that might be better at reducing emissions.
He would need to take into account the emissions associated with any materials or equipment that he would need to purchase to reduce his home's emissions.
These principles are related to each other, of course. Let's say that Thomas calculated that he would spend $100 per tonne of reductions by adopting a particular course of action. He might conclude that that price was too high compared to other things he could do with the money to help the environment. For example, he could purchase offsets (if he were to choose them very carefully), or he could donate to a political party that will actually do something about Canada's carbon footprint.
Thomas first considered whether to insulate his home better to reduce its carbon footprint. If Thomas were to spend money on insulation then it would have had to come out of his savings, which were earning (let's say) 4 percent annually net of inflation and taxes. He also assumed that the insulation would last 30 years.
To insulate to achieve a 90 percent reduction of emissions from heating, Thomas would have needed to tightly air seal his home and then upgrade from R-3 (the effective insulation value of his brick walls) to at least R-30. He would also have had to install a heat recovery ventilator because of how airtight his house would have become.
Insulating on the outside of his home would cost, say, $160 per square metre and require covering over his brick walls with at least four inches of insulation plus siding. Thomas preferred the look of his house's brick exterior, and it would cost
to install the insulation. He would also have needed to insulate the attic and purchase the heat recovery ventilator. The total cost would have been at least $35,000.
If we assume that the insulation would last 30 years, and if we assume that Thomas would have earned 4 percent per year after tax and inflation on that $35,000, we can see that he would have foregone earnings of
per year by installing the insulation.
Thomas also needed to take into account the emissions associated with the insulation, materials, waste and labour associated with insulating his home. One way to calculate these emissions is to multiply the estimated cost of the insulation option by the GHG intensity of the Canadian economy as a whole. In 2018, Canada emitted about 0.35 Mt of CO2e per billion dollars of gross domestic product. This implies that, for every dollar a Canadian spends, he or she "emits" 0.35 kg of CO2e. The insulation project, then, would result in the emission of an additional
The savings over the 30 year life of the insulation will then be
or 4,146 kg of CO2e saved per year.
This works out to paying about $488 per tonne of emissions saved. $488 per tonne of emissions is a pretty high carbon tax to pay. Thomas asked whether there was another, cheaper way to reduce his home's emissions.
Thomas crunched the numbers and decided that heating his home with an air-source heat pump would be the better option.
In 2017, Ontario had pretty clean electrical energy: our grid emitted about 40 grams of CO2 per kilowatt (kWh). One estimate (pdf) from The Atmospheric Fund for 2018 gave a figure of 31 gram of CO2e per kWh, but to be conservative (and to anticipate this figure increasing because of the Ford government's irresponsible climate "policies"), let's use the 40 gram figure.
Thomas estimated that he could replace the 2,300 cubic metres of natural gas he used for heating each year with an additional 8,037 kWh of electricity. In other words, Thomas estimated that each cubic metre of natural gas for heating could be replaced by 3.49 kWh of electricity. Therefore fuel switching would add
to his home's consumption of electricity each year. (How much electrical energy will be needed to replace a given amount of heat provided by natural gas will vary from house to house depending on a number factors, including the efficiency of the existing gas heating system. Thomas' estimate for his home turned out to be quite accurate, however: it has matched his actual usage fairly closely.)
Thomas calculated that his home's CO2 emissions for heating would then be
per year instead of 5,060 kg of CO2, which represented an emissions reduction of about 94 percent. You can follow along with his calculations here.
Of course, he also needed to take into account the emissions associated with purchasing and installing the heat pump, electric hot water heater and backup resistance heaters. (Some homes might require an upgrade to the their electrical panels as well. Thomas' home did not.) The total cost of this conversion ended up being about $6,000 more than it would have cost to replace his aging furnace and hot water heater. Amortized over the ten-year expected life of the new system at a 4 percent investment return rate meant that this part of the annual cost of his fuel switch was only
But that wasn't the whole story. Completely switching off natural gas also saved money each year. Thomas doesn't pay $300 per year in natural gas customer fees (the minimum annual charge for a natural gas hook-up). The new system also provides cooling in the summer, which was a benefit he did not get from a natural gas furnace. Thomas also freed up 2 square metres of floor space in his home, which he valued at about $250 per year.
By switching, Thomas expected to save emissions equal in total to
This is the cumulative CO2e savings over the ten-year life of the heat pump, less the CO2e effect of purchasing a heat pump and having it installed. Thomas, then, expected to save about 4.5 tonnes of CO2e per year at a cost of between $40 and $100 per tonne - depending on how the ongoing savings are valued and compared to using natural gas. Note that anyone currently heating with fuel oil or propane will save both money, perhaps 50 percent of your annual bill, and emissions.
Making the switch to electricity for heating represented good value for Thomas per tonne of emissions reduced. Thomas ended up adding some insulation to his home recently, but he did it more to make his home less drafty rather than to save emissions. He addded about 5 centimetres of foam insulation around three sides of his home, which added R7.6 of insulation to the house and made it much more airtight. He estimates that the insulation will improve comfort and reduce his electricity consumption this winter by 40 percent (which will reduce his emissions even further, of course).
Nevertheless, Thomas' made the biggest cut to his emissions for the least amount of money by fuel switching. Thomas' cost per tonne would be reduced even further if fuel switching were more common. Higher demand for heat pumps will help to encourage innovation so that they become even more efficient, and as production volumes increase, prices should come down (just as they have for solar panels). Moreover, as installers and HVAC companies become more familiar with the technology, their prices for selling and installing the equipment should fall too.
Thomas was able to make the switch and save emissions with his old house at a relatively low cost, but it did cost him some extra money. Not everyone can afford the extra cost, and not everyone will make the switch when their choice for heating is between electricity and natural gas, which causes environmental damage that doesn't cost the user anything.
Governments can address these issues in a number of ways.
First and foremost, governments should not be adopting policies that will make fuel switching less efficacious from an emissions perspective. The Ontario government has adopted policies that will make Ontario electricity more carbon intensive, not less. Heat pumps will reduce emissions only to the extent that the electricity they use is generated with a lighter carbon footprint.
It is also necessary to consider the bigger picture for fuel switching. Thomas's fuel switch meant that he started using an additional 8,000 kWh of electrical energy each year. Ontario hardly noticed the additional demand because, in 2018, Ontario generated about 151 terawatt hours of electricity, which is 151,000,000,000 kWh. Thomas' additional usage was not even a blip in a blip.
But the marginal demand for electricity in Ontario is met by burning more natural gas, and the amount of gas burned to meet that demand will only increase, if the Ford government has its way. The annual marginal CO2e footprint of Ontario electricity is considerably higher than 40 grams per kWh. The Atmospheric Fund estimate referred to above put it as high as 134 grams of CO2e per kWh in 2018. The climate-conscious efforts of fuel switchers like Thomas will be undermined if government policies mean that any extra demand they create for electricity ends up being supplied by natural gas generation. If fuel switching becomes a mass movement - as it must, if Ontario is to meet its climate goals - then the government will need to find a way to bring down the carbon footprint of marginal electricity production.
Governments can also help with affordability. For example, they could provide low-interest loans to help citizens address the higher upfront costs of fuel switching. Right now there are incentives for retrofitting home insulation, but the cost per tonne of emissions reduced seems to be much higher than for fuel-switching. Governments should re-focus their incentives to fuel switching so that consumers avoid using natural gas altogether rather than just using less of it.
The federal government might consider creating rebate programs for fuel-switching funded with revenue from the carbon tax. The government should also shut down rebate programs for natural gas and, finally, end fossil fuel subsidies.
Even more importantly, the carbon tax should be maintained and increased over time in a predictable manner to provide better incentives to switch fuels.
Ontario should ensure that trade schools are providing adequate training for HVAC installers on fuel switching in general and heat pump installation in particular. In our (admittedly limited) experience, HVAC suppliers are not as comfortable with heat pumps as they are with more traditional heating methods.
Finally, the Ontario government and cities should amend building codes and by-laws should be changed to ban or make it more expensive to continue installing natural gas. We are in a climate emergency. It makes no sense to permit the construction of new homes and other buildings with gas heating when we are supposed to be aiming for a 45 percent reduction of emissions by 2030!
Anyone who is interested can follow the steps in Thomas' blog and make a big difference to the carbon footprint of their home or business. That's the good news.
More needs to be done, however, so by all means impose a "carbon tax" on yourself to help decide where you can best invest your money.
Spare some thought, however, to giving some time and money to organizations that will advocate for government policies that will support your efforts.
You must be logged in to comment.
There are no upcoming events right now.
Why not post one?