3) It's difficult to start with a fully formed idea that works everywhere. LEED is slowly growing and adapting. LEED started in the US and became very popular. Others outside of the US wanted to use it too. Some have customized LEED to their own local standards. Tristan mentioned that there's also talk of an international version that's in developement.

With so many nations and so many standards it takes a long time to learn details about all of the standards, common business practices, and forming them into one performance metric that is strict enough to show a significant improvement over the average building.

I imagine a building in the top 10% energy efficency performance in Germany is a bit different than one in the top 10% in China. What may be good design in one country can be average in another, and overly strict in yet another. What may be important to one country may not be important in another. How do we write one standard that is good everywhere?