Local Law 84 (LL84) is part of NYC's Greener, Greater Buildings Plan. Enacted in 2009, LL84 mandates annual benchmarking data to be submitted by owners of buildings with more than 50,000 square feet for public disclosure. This data is made public on NYC Open Data's site. For this visualization, I used the 2012 data set available here.
This set contained data identified by a building's address, zip code, and borough. The primary metric that I used was EUI, the building's Energy Use Intensity. The data included a secondary metric, Indoor Water Intensity, which I omitted from this visualization for ease of understanding. The EUI is measured in kBTU per square foot. This is not a conclusive metric on its own, as there's a plethora of factors that can influence this one-dimensional nubmber. However, it does begin to shed some light on the question of energy usage in NYC buildings. In the future, it would be interesting to visualiza this data takingg into account the age of the building, construction materials, number of adjacent buildings, glazing, etc.
The main problem I had to overcome working with this data is that it was flat. So I used Underscore.js to convert the data to a hierarchical JSON format. I then used D3.js to create a sunburst hierarchical partition. The innermost ring represents the five boroughs of NYC that supplied the data. The middle ring represents zip codes within the boroughs. The outer ring is the EUI data in kBTU/ft2.