Sustainability Hacks: The Easiest Way to Measure Your Energy Use Index
By Jack Bullock
Chief Engineer, PE, CEM, BESA
The energy use index is one of the most critical measurements of energy use (EUI) and performance of facility assets available. On the surface, EUI alludes to the annual energy use in relation to the square footage of each building and overall facilities. Unfortunately, knowing how to measure your energy use index properly comes with significant challenges, and education facility managers may not realize how continuous monitoring of the energy use index can influence energy management decisions.
Common Challenges When Trying to Measure Your Energy Use Index
The challenges of trying to measure your energy use index derive from two issues, including the age of information and the ability to aggregate data. By its nature, it is impossible to calculate the energy use index without knowing the specific energy use for an entire facility, and at the same time, older information may result in reduced accuracy of the energy use index today. As a result, education facility managers will need to invest in an energy management program that will enable real-time visibility into assets and improved energy monitoring.
Why Visibility Into Asset-Level Data Is Crucial to Proper Measurement
Visibility into asset-label data plays a significant role in understanding a building's overarching energy use index, but it has additional implications for multi-building campuses. For example, facility managers can determine the energy use index for each facility and as a district empowering the superintendent and school board members to know which buildings are under-performing in relation to the entire district. Therefore, better decisions can be made to identify the causes of increased energy use and encourage energy-conservative behaviors among affected building occupants.
How to Calculate Your Index With 100% Accuracy
Calculating the energy use index is a simple formula. The energy manager should divide the annual energy use in relation to kBTUs for the whole facility by the total square footage for the facility.
Total Energy Use Converted to kBTUs / Total Square Feet of Your Facility
For reference, convert kWh to kBTUs with this formula: kWh * 3.412.
It is important to consider space that routinely goes unused, such as storage closets, mezzanines, and upper floors. Although the energy use index is typically applied to an annual view of the energy consumption of a facility, it is possible to calculate the energy use index on a more frequent basis, such as monthly, quarterly, weekly, or even daily. Unfortunately, facility managers and education staff do not have the time to run the calculations and keep track of the energy use index for each period of measure. Furthermore, calculating specific floor-level or zone-level EUI is impossible with knowing the exact energy consumption for each area. Identifying the exact energy consumption of each area is where Cenergistic can add value to your energy management program.