Chicago Energy Consumption

The Chicago Energy Database Map is a multivariate visualization of electricity and gas consumption in Chicago neighborhoods. The map uses both color and height in order to show two different variables. Gas consumption in each neighborhood is shown on the map using color, while the height of the neighborhood reflects the amount of local electricity consumption.

Using 3d towers and color allows the map to show two different variables at the same time. The result is an effective visualization of energy consumption in Chicago, as users can clearly see that both gas & electricity consumption is lower in the city center than in the surrounding neighborhoods.

The Chicago Energy Database Map does have some problems as a multivariate visualization but these problems are largely due its age.The map is a few years old now and appears to have been designed in Leaflet using some trickery to provide the oblique bird's eye view of the city map. The result is that the user can't tilt the map and can only rotate the map in 90 degree stages. This can make it a little difficult to view all of the neighborhoods on the map, as the taller neighborhoods in the foreground can obscure any shorter neighborhoods behind them.

Today the map could be created using a modern vector map library, such as Mapbox GL - which supports pitch & bearing. If the map was recreated in Mapbox GL the user would be able to tilt and rotate the map at will and would be able to explore the data more easily. You can view some examples of 3d towers being used to visualize two or more variables in this post on Mapping Population in 3D. You can view a few other methods of mapping more than one variable in Jim Vallandingham's Multivariate Map Collection.