Though they put a good face on it, advocates of smart growth will find little to cheer about in a new report from the National Academy of Sciences on using compact development to reduce driving and greenhouse gas emissions. The report says that, if three-quarters of all new and replacement housing is built at twice current densities, it would reduce driving and related CO2 emissions by only 8 to 11 percent by 2050.
Hardly anyone thinks that even the most restrictive government planning can double the density of 75 percent of new development. As a summary of the report given at a congressional hearing this week noted, the committee that wrote the report (most of whom are fairly objective people) “disagreed about the plausibility of extent of compact development and policies needed to achieve high end estimates.”
If a more reasonable figure of 25 percent is used, then CO2 emissions from driving would be just 2 percent less. Since driving autos accounts for only about 20 percent of greenhouse gas emissions, a 2 percent reduction from that is pretty small.
