> increased HVAC usage at home

At least to a thumbnail sketch, back-of-the-napkin calculation, I'd guess not. Most American homes don't have smart thermostats and people just leave their system set to "comfortable" all day long, whether or not the home is occupied.

Also, there are large swaths of the US where air conditioners are not common.

> In hot or cold weather, transit emissions savings may be more than offset by increased HVAC usage at home.

Most people keep on heating/cooling their home while they are at their office; sometimes to a lesser power, sometimes the same all the time. Office which is also heated/cooled (and had to be built one day, often terribly). So with a regular job, your home emits, your office emits at the same time, and the transportation between those emits too (and had to be built).

AC at home is rare in Europe.

Most of Europe has both lower temperatures and humidity when compared to the United States.

Let's hope it stays like this. I'm dreading summer already as the last one had temperatures reaching 40°C here in Europe.

Flying accounts for ~3% of carbon emissions, of which business flying is another subset.

The aggregate reduction in economic activity is significant though. Oil prices are halved from their pre-outbreak levels.

Oh for sure, I don't expect it to have any significant impact.

Interesting point regarding HVAC usage, I am curious to see the density required for it to become a net positive.