Generally speaking, you're correct. Any new building, no matter in the short term.... If we think about 2030 leading up to 2050, any new building will contribute some form of carbon during construction or with the materials; there will be some contribution. But it creates the building stock of the future, so if you build more zero carbon buildings, by 2050 you'll have way more buildings that emit less carbon. In terms of the net gains right now, between now and 2030 and 2050, most of the net gains have to come from existing buildings. Cutting existing emissions—that's the key strategy.
On March 20th, 2019. See this statement in context.