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Facility Variables

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  rev. 2011-04-27        

Quite often there will be utility use influencing factors that are outside of the control of energy managers and building operators.  In mathematical language these are known as independent variables.

The most commonly-used external factor, weather, is represented as two independent variables: Heating Degree Days (HDD) and Cooling Degree Days (CDD).  ManagingEnergy stores mean daily temperatures  for weather stations around the world.  HDD and CDD values are calculated automatically without any user entry or intervention.  Other independent variables, known in ManagingEnergy as Facility Variables, are unique to each facility and so must be set up and entered by users.  In our experience, most residential, commercial, or institutional facilities do not require any Facility Variables for effective energy accounting.  Most industrial facilities require one or two.

Facility Variables add to the amount of data collection and data entry, so they should be chosen with some care.  The following characteristics are important for any Facility Variable:

Known or suspected to have a significant impact on utility use.
Accurate information is available for the baseline period and easily collected in future for monitoring and verification.
Values can be collected and entered at any frequency.  An exact match with each billing period gives the most statistically precise results, but is not essential for ManagingEnergy to provide valid output.

Facility Type

Example of Reasonable Facility Variable


number of days each month that classes are in session

Apartment Building

number of suites rented

Steel Foundry

tons of steel melted


hot meals served


days of refrigeration plant operation

To create a new Facility Variable, select a facility node in Tab 1 in the Facility Tree and click on Facility Variables in the Tasks area.  Enter the name, a measurement unit (keep it short), and any notes.  Click Save Facility Variable when you are done.

Use the same form to change the definition of an existing Facility Variable, by first selecting the item to edit from the list on the left.  Be sure to click Save Facility Variable before clicking Done to leave the form.

Impact on Baseline Modeling

Baseline models have to take Facility Variables into account, during the baseline year and after.  If you are going to use a particular Facility Variable, you must have the data available for the Baseline Period.  If the data is not available over the preferred baseline period, the only mathematically valid choices are to change the baseline period or not use the facility variable.


Related Topics

Edit Variable Values

Weather Data


S5_Facility_Variables         ©2014 Managing Energy Inc.