This study examines the rental rate dynamics of green commercial office properties in the San Francisco and Washington DC metropolitan areas. We match the list of U.S. Green Building Council (USGBC)-certified commercial office properties in the two areas with property-level temporal and non-temporal data derived from USGBC and CoStar for the period 2007:Q1 to 2010:Q1. We find that, similar to previous studies,green office properties enjoy rental rate premiums over comparable nongreen buildings. However, we also find the premiums to be dynamic instead of constant. Our models suggest that green property rents may provide a hedge in down markets.