Historical energy use analysis has always been a retro-commissioning activity performed off-site. However, it is especially valuable for virtual retro-commissioning as a means of identifying potential energy savings opportunities without being in the building.
The quickest and easiest, and almost always applicable, analyses are base versus seasonal usage and load factor.
Base versus seasonal usage: Figure 1 is an example of electric consumption (kWh) data for six years, starting in March 2014 and ending in March 2020. This was for a small home in a four-season climate zone. In this case, there are clearly two seasonal “bumps” in the graph profile. This indicates an all-electric building, i.e., both winter heating and summer cooling is provided through electricity. That happens to be true for this home (heat pump system), but when performing a retro-commissioning analysis, we need to ask whether the profile is reasonable for each unique facility.