I hate when authors don’t just stick to the yearly numbers. Here they are actually giving a 15 year figure (I’m more used to 10 year figures like the way health care costs are sometimes quoted). From the paper:
The reduced energy use could save residential and commercial ratepayers an average of $82.7 billion annually between 2020 and 2035 for a cumulative savings of $1.3 trillion (see Figure 3 on page 12)
(I did the computation below before I saw this - I’ll leave it here for reference)
The 300 million metric ton number (for 1 year) looks to be the right order. https://www.eesi.org/files/climate.pdf gives 2236 million metric tons of CO2 for 2004 building usage which is 39% of total US emissions. So saving on the order of 10-15% sounds OK.
The cost that 1 ton of CO2 when converted to natural gas (not including a carbon tax which I would want) is I think:
From https://www.epa.gov/energy/greenhouse-gases-equivalencies-calculator-calculations-and-references, 0.0551 metric tons CO2/Mcf where Mcf = 1 thousand cubic feet (what the hell? M = 1e3? I hate English units). And finally natural gas price moves around but let’s say $15/Mcf (https://www.eia.gov/dnav/ng/hist/n3010us3m.htm).
So we are at:
(15 dollars/Mcf) x (1 Mcf / 0.0551 metric tons) x (300e6 metric tons) = 82 billion dollars (almost a perfect match to the paper)