Density is a critical tool to reduce energy usage and combat climate change. Urbanists and environmentalists should be working together on development of cities and density. The study also highlights why one cannot be and environmentalist and anti-density at the same time - they are contrary to each other.
"Density gets you slightly more reduction in building energy use than efficiency does, if you do it right.
If you do both, you get the best result:
For the high urban density and advanced efficiency scenario combination, the annual building energy use for heating and cooling first plateaus around 2030 and then decreases after 2040, settling just below 45 [exajoules] in 2050."