90 by 50: A Few Thoughts

New York City’s Urban Green Council has released a report, 90 by 50, that charts a path towards a 90% reduction in municipal greenhouse gas emissions by 2050–and does it with technologies that are available today and without requiring massive behavioral change. Slate provides a detailed review here, but I’ll add on a few thoughts on this ambitious roadmap.

  • The plan’s biggest target is building energy usage, which is a tough nut to crack: as Slate puts it, “Inefficient buildings are much harder to replace than inefficient cars.” However, a citywide program of gradual retrofits–individual and district geothermal heat pumps, triple-glazed windows and better insulation–is projected to drastically cut GHG emissions and energy requirements in the long term. However, given that property owners tend to be risk-averse and have higher-than-normal discount rates and payback requirements for efficiency measures, this seems to require either strong regulations for building upkeep and retrofit, or some kind of reworking of utility serving to include not just energy but energy efficiency measures as a combined service.
  • One of the few individual-level sacrifices the plan calls for is curtailing the use of glass curtain walls. As the UGC’s Dick Leigh remarks, “People want buildings with huge expanses of glass. But no matter how good the glass is, it’s not going to be as good as an insulated wall.” While Leigh is technically correct, I wonder if this isn’t a misguided stand–sweeping views and better natural light are real amenities, and ones that make small high-rise units more livable. New Yorkers generally seem willing to live at very high densities, but elsewhere I wonder if the marginal gains in building performance make up for losses in residential density.
  • Electrifying the transit network? Yes. Doing it with trolleys? Not so fast. Surface trolley networks can make sense in cities that need to revitalize tourist districts or that want to signal a commitment to transit improvements before it has the population or ridership to justify real rapid transit. Does that sound like New York City? Moving towards a low-emission and/or electrified bus fleet is almost certainly a better use of funds.
  • This just goes to show how firmly big cities are situated at the forefront of climate change mitigation compared to the US and Canadian federal governments. When’s the last time you’ve seen a feasible and pragmatic plan this ambitious considered seriously at the national level?



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