After calculating the lighting serv

After calculating the lighting service, or lumen-hour, demand in 2013 by sector and submarket, the next step was to project forward the lighting demand for each year through 2030. To do this, the 2013 lumen-hour demand was divided by the cumulative national floor space for each sector to determine a lighting demand density in lumen-hours per square foot of building space. Then, assumed floor space growth rates were applied to these densities to project total lighting demand for each sector from 2013 to 2030, holding lighting demand density (kilolumen-hours per square foot) constant. In the residential sector, the average lighting demand density in 2013 was approximately 16.3 kilolumen-hours per square foot, while density in the commercial sector was more than fifteen times higher, at 304 kilolumen-hours per square foot. The commercial lighting service was higher due to the longer operating hours and higher levels of illumination in commercial floor space.