Calculating energy savings results is like keeping a golf score. If you ever been on the green, understanding the meaning of CUSUM will come easy.
Baseline – how machine is supposed to work or worked before retrofit – is a par.
CUSUM – a cumulative sum of deviations from baseline – is a score.
If CUSUM is above par, machine wastes energy compared to the baseline period. Something goes wrong.
If CUSUM is below par, machine works more efficiently than during the baseline period, you are getting energy savings.
Tell this to you CFO and you will never have to explain value of CUSUM again.