This document summarizes the top 10 conceptual hurdles to greater investment in energy efficiency. It discusses issues such as how construction lending differs from lending on stabilized properties, the different risk cultures across real estate asset classes, the fallacy that if there is no market data the value is zero, focusing on low hanging fruit improvements over deep retrofits, timing efficiency upgrades with capital expenditure cycles, and only considering cost savings without other potential benefits. It also addresses issues like the simple payback fallacy of not including reversion, incentives needed for renewable energy similar to subsidies for fossil fuels, greater emotional impact of potential losses over gains, and how complex credit issues have been solved before through mechanisms like credit enhancement.