At least in the United States, it sort of depends on where you are. In California, most of the greenhouse gas emissions right now come from the transportation sector, and certainly most of the air pollution comes from the transportation sector. However, in other parts of the country, where heating heating loads are higher or air conditioning use is higher, the buildings tend to account for more of the energy used. Given the large number of buildings the U.S. government owns or leases, reducing building energy use has certainly been a big emphasis in its greening efforts.
On April 2nd, 2019. See this statement in context.