Facility Variables are operating characteristics, other than weather, that change regularly and influence energy use. They are often called Production Variables because they have something to do with the production or purpose of the facility.
|•||Tons of production (for a steel manufacturer)|
|•||Number of vehicles assembled (auto manufacturer)|
|•||One hour ice rentals (for an ice arena)|
|•||After hours community-use permits (in a school)|
|•||Room rentals (hotel)|
Facility Variables are defined at the Facility level in the Facility Tree under the Buildings & Meters tab. Assign Metric values to each Facility individually in the Facility Tree. There is no need to assign a value for every Metric to every Facility, and in fact a single Metric might only apply to a few facilities in a portfolio.
Use Facility Variables only where you are dealing with a quantity that significantly influences energy use and that changes frequently enough to register in the baseline model. ManagingEnergy cannot determine statistical significance in a baseline model if the variable has not changed through the baseline period. If you try to track too many Facility Variables in one facility, you may find they all become statistically insignificant or that you don't have enough baseline information to differentiate the effects of one from the others.
Secondly, choose only facility variables that you will put the effort into tracking and recording. If you are not collecting the data regularly, it takes a lot of work to collect, or it arrives more slowly than you need outputs from ManagingEnergy, it may be better to leave it out.
For correct calculations on a dashboard, report, or export, all Facility Variables must have values assigned for the time period of interest. Variables do not necessarily have to be updated at the same frequency as meter readings. Quite often users will set the end date of the last entry in the future to ensure that current calculation periods are covered.
What About Changing Floor Area?
Floor area is a standard facility property, accessible in the General tab under Edit Facility. However, buildings evolve and periodic floor area changes are quite common. Many organizations will find it important to track changes to floor areas over time.
A good example of this is school districts where portable classroom space is being added, removed, and rearranged each year to follow the student population. Portable classrooms have a clear impact on utility use, and energy performance would be impossible to track properly if they were not considered.
Floor Area is automatically defined within ManagingEnergy as a changing Facility Variable.