Q: I have a question about how to use option C savings evaluation and how to overlay or use that information to inform EUL or apply a stipulated EUL to estimate lifetime savings for a collection implemented similar measures.
My use case is for a utility project that comprises 3 facilities and about 10 meters where will be "installing" RetroCommissioning. M&V is 2 years and EUL (median measure life) is stipulated by the regulator at 3 years. Do you have any methods or protocols suggestions for estimating the lifetime savings of the measures at the end of year two? Simply multiplying the sum of Y1&Y2 avoided energy use by 3/2 would assume that all measures will fail precisely at the end of year three, which would obviously under-estimate the lifetime savings. It seems like a survivorship problem (e.g. a 71 year old human is expected to live to an older age than an infant).

One other element is that after initial implementation of the RCx measures, we may stay engaged with the customer to monitor energy use and maintain the savings over the M&V period. How would this effect the approach to the prior problem statement.

A: This doesn't seem to be an M&V question, but rather a measure life methodology question for a group of measures, so its not strictly in the realm of M&V. I can suggest a few things to think about. First, how are RCx measure savings EUL determined? I don't mean by regulatory rule, but in persistence studies? RCx by nature is correcting building system operations, whether deficient, in need of repair, or improving control strategies. It seems the testing or analysis done to identify the measure can be repeated in years 1, 2, 3, 4 and so on. If your company stays engaged, this is a possibility. If not, maybe integrate these testing practices into the building's regular operations. At the outset, use a weighted average EUL for the combination of measures and determine the Option C savings associated with it (estimate normalized savings under typical conditions, as is the practice in cost-effectiveness calculations). With each successive year, see if the measures are still operating correctly. Determine some method for adjusting savings/EUL in the successive years as measures cease to save.