Overlay Graph

Overlay graphs allow users to quickly compare different time periods for a selected variable. This allows users to spot trends or deviations.

High School Electricity usage being viewed. Each plot shows one week of data, the red plot shows October 11th to October 17th, the green plot shows December 20th to December 26th and the blue plot shows August 2nd to August 8th. From the red plot you can clearly see that the weekend usage is much lower then the weekday usage. This is as would be expected given that the High School is closed on weekends. The green line shows that the electricity usage is very low during this week due to Christmas vacation. Finally the school is closed in the summer time and therefor the blue plot show a very low usage.
To lower the electricty cost you would look to lower the base usage (30 kW during the school year) and lower the weekend usage as much as possible.

Here electricity usage is compared between months. Comparing November 2008 (black plot) and November 2007 (red plot) you can clearly see that the base usage for the High School has increased from 10kW to 28kW.  If nothing is done then this will result in a great increase in electricity cost for the High School.

Overlay Graph showing Air Temperature for January 2008 (blue line) vs January 2007 (pink line).

Overlay Graph showing Air Temperature for the year 2007 (black line) vs 2004 (brown line).