Over the last several years, many major utility and statewide energy efficiency programs have adopted some form of a Technical Reference Manual, or TRM. These documents usually provide, at minimum, a single location for all of the baseline and technical assumptions, equations, and requirements which utilities and implementers have developed for their prescriptive (deemed) savings values. This generally provides program administrators with an easy, straightforward, consistent, and independently verified (hopefully) way to determine energy savings for common energy efficiency projects. However, the types of measures in a TRM can vary from jurisdiction to jurisdiction.
Nationally, there are a large number of measures that show up consistently. These would include lighting upgrades, motor replacements, residential and commercial appliances (think anything ENERGY STAR rated), pump variable frequency drives (VFDs), and residential and commercial heating and cooling equipment upgrades. However, there are some TRMs that go well beyond those “typical” prescriptive measures to include more complex and less common measures such as compressor upgrades, greenhouse films, irrigation pumping VFDs, constant volume to variable air volume conversions, and booster pump system configurations.
Expanding a TRM to include every measure or measure combination may seem like a great idea, but it brings along some important considerations. The first, and most important, is calculation accuracy. The more specific or complex a measure is, the more difficult it becomes to find robust and accurate data and literature to substantiate savings claims. The second reason is that once a TRM is written, it is not engrained in the cosmic firmament. These documents require in-depth evaluation and updates, often occurring annually. The longer and more complex TRMs become, the more time and resources (especially dollars) it takes to keep them current and accurate.
Now don’t mistake this as condemning all forms of TRMs. They provide an extremely useful function and are a great resource for utilities, program administrators, evaluators, and other stakeholders. Just remember to keep the measures in the program’s TRM to those that are easily quantifiable, backed by extensive robust data, and have consistent high participation. Remember, the goal of the TRM is to accurately represent the average occurrence of a measure over a large number of installations. If a measure does not have a large number of participants, the actual savings realized by customers will vary significantly.
Don’t forget, there is always the custom program for those one-off measures.