Ah, the old "it doesn't matter if we do X, so long as we do Y" where "X" keeps shifting to whatever the arguer wants it to be in that moment. In this case "X" is the 860,000 US office workers driving fossil fuel cars back and forth to work every day for their entire working life, which I was told was a bad thing, but now it actually doesn't really matter.
The average car in the US emits 350 g CO2 per mile [1]. The average American commute is 40 miles [2]. That's 14 kg of CO2 per commuter, or 14 million kilograms per 1 million commuters. So, about 14000 tons of CO2 per day, or about 5 million tons per year. 5 MT.
Every year the US emits about 5 GT of CO2 equivalent [3]. If a million people stop commuting right now, the US will reduce its emissions by 0.1%.
[1] https://www.energy.gov/eere/vehicles/articles/fotw-1223-janu...
[2] https://www.zippia.com/advice/average-commute-time-statistic...
[3] https://www.epa.gov/ghgemissions/inventory-us-greenhouse-gas...
Look, some people want to work from home, and it's good for a lot of reasons, but climate has nothing to do with that.
https://www.epa.gov/ghgemissions/sources-greenhouse-gas-emis...
Since car commuting also correlates with other negatives, that seems like a good thing to try to reduce since there are very few downsides — someone giving up their commute is _happy_ about it, unlike a business being asked to stop using an industrial furnace or a farm being told they shouldn't truck in feed. Every bit we save in one area gives us more time to work on the others.
Big relative to what?
Let's run the numbers.
For a 2000 sqf home the AC consumes about 3-4 kW of electricity [1]. The vast majority of electricity in the US is produced with natural gas, where 1 kWh of electricity results in about 0.5 kg of CO2 [2]. Let's say 1 million people run the AC for 10 hours per day during the hot season, which is roughly 100 business days per year. That's 40 kWh per day, or 20 kg per person, or 20000 tons per one million people. Multiplying with 100 we get 2 MT of CO2.
Heating is probably similar. Obviously heating does not happen at the same time as AC, and people in the Southern states use more AC, and those in the Northern ones use more heating. Anyway, let's say heating adds another 3 MT of CO2, so overall the commute and the AC and the heating come to 10 MT of CO2 or 0.2% of the emissions.
[1] https://itlandes.com/how-many-watts-does-an-air-conditioner-...
Also, I thought of another thing you should factor in: restaurants. They're incredibly wasteful with food. With no office workers, many restaurants (especially around offices) have drastically fewer customers. You'll need to include the carbon savings from some percentage of the food that goes to waste.
Yes, I was just being conservative. The savings on the office side would be much lower, because as I said, offices are more efficient than homes. Plus, most offices would not close if people work from home.
As for restaurants, you are going into second and third order impacts. Why not calculate the savings from all the dry-cleaning that doesn't happen because people can work in their sweat pants at home?
Yes, that's what systemic change is, and you appear to be presuming (with your mocking jab about sweat pants, give me a break) that it's irrelevant to study second and third order effects of large social changes. That's not a very credible perspective to have.