I've gotten this question a lot recently. Partially because of the continued drumbeat of cities releasing private-sector building energy consumption information (New York, D.C. and soon Philadelphia), but mostly because of the deliberately misleading attack on LEED buildings recently made by an anti-green front group based on the D.C. benchmarking data.
Of course there is no reason to pay any attention to the front group or their bizarre crusade to save us all from fresh air and daylight, but there are many reasons to understand what a high EUI might mean.
EUI is energy use intensity and is simply energy use per square foot of space. Most of the time you see it, it has had the impact of weather variations taken out. So lower EUI is better and more efficient than higher EUI, right?
Maybe. Depends on how you define efficiency. Sometimes buildings are very efficient and still use a lot of energy. Buildings with server rooms, trading floors, or just with lots of people can use lots of energy, but do so very efficiently. It would not be a good idea to require all buildings to have the same low EUI without accounting for this context, because that would pit space efficiency against energy efficiency in some applications.
And what if economic activity is part of your definition of efficiency? Empty buildings without much activity happening in them will probably have low EUIs, but they are a waste from an economic perspective.
SAT scores aren't perfect measures of student ability. FICO scores aren't perfect measures of financial well being. Body weight is not a perfect measure of healthiness. But all are crucial parts of showing us the big picture, just like EUI.
Kudos to D.C. and other cities for allowing us to begin to think about energy waste in buildings.
Ignore the front group. They are basically trying to convince you to drive Hummer instead of riding the bus, because the bus has a worse MPG.