Cumulative sum of savings (CUSUM) is a line representing the difference between expected vs actual energy to track performance over time. The CUSUM shows trends throughout a year and answers the question, “How has my facility performed over the past year since the start of the program?”
CUSUM begins at the performance period start date and accumulates for a savings-to-date total
The steeper the CUSUM slope, the greater the difference in expected vs actual model data
Hover over the most recent data point on the CUSUM line to view your cumulative savings to date.
CUSUM savings graph
Did you know?
Depending on your program, the cumulative savings line is expressed as ‘up is good’ (default) or ‘down is good’. For a program using ‘down is good’, the legend will be labeled as such.
Gap in CUSUM
Gaps in the CUSUM view are most often intentionally excluded days or missing data. If the CUSUM and Expected Energy show the same gap, it is most likely due to either excluded day(s) or missing data.
Check for an event on the CUSUM explaining the reason for the gap. If it’s a known gap, no further action is needed.
Check production or facility data for the most recent date. If needed, send recent production data.
CUSUM savings graph showing a gap in data
Add an event for excluded days in a model. Excluded days (for non-routine events) cause a break in the CUSUM. The event explains the break so others know it is an exclusion and not missing data.
Add an Event
During your energy program, it’s important to track events that impact performance. You can add an event to your CUSUM view to track site activity such as equipment shutdown or a power outage.
Click on the graph where the event occurred
A dialog box appears. Enter required fields: EventDates, Name, and Description. By default, events are Public and can be viewed by other users with credentials for your facility. If you want the event to appear on your graph only, uncheck Public.
Dialog box to create an event
Edit or Delete an Event
Click the event circle on your graph to open the dialog box