This document summarizes research on the diffusion of energy efficiency in commercial buildings. It finds that: 1) Energy efficient technology, as measured by Energy Star and LEED certifications, has diffused rapidly in commercial buildings, reaching 30% and 11% of office space respectively. 2) The timing and growth of adoption varies significantly across markets, correlating with factors like income, energy prices, and property market conditions. 3) Dynamic regression models show adoption is higher in areas with stronger economic fundamentals like higher incomes and sound property markets. This suggests underperforming real estate markets may lag in energy efficiency.