On the Massive Carbon Savings of Gentle Density
If it were legal everywhere, Michael Anderson writes, gentle density would confer massive carbon savings and ease the transition away from fossil fuels.
To illustrate, Anderson poses a thought experiment where three large new homes are constructed on one block, while a duplex, triplex, and fourplex are built on a site of the same size. "If we compare these two blocks after all the new homes are complete, the housing-related carbon emissions per household of the Plex Block will be about 20 percent lower," he writes.
It makes sense that smaller living spaces cost less carbon (and dollars) to heat in the winter and cool in the summer. And in the case of the McMansion, most of that space isn't even lived in.
Anderson also notes that when "missing middle" housing is permitted, the positive environmental effects extend to transportation. "This density effect is probably strongest if it's creating new options for living in a transit-rich, walkable area specifically for people who want to live a low-car life but couldn't previously afford that sort of neighborhood."