Are your energy bills hiding energy savings?

Photo by Flickr user dougwoods

Billcast delivers laser-like variance analysis, revealing savings even if rates change or hot weather clouds the picture

Take a look at the bills below for a small commercial building. Below the monthly cost, you can see the year-on-year change. The July and August bills saw nice dips, followed by a big 17% jump up in September.


This building installed a large controls project in June which they expected to save about 8% of total energy spend. This is every facility manager’s worst nightmare — a large investment in energy efficiency followed by an increase in the utility bill! My stomach churns just thinking about the nasty call from the asset manager.

Of course, a variety of factors influence bills and the change from year to year (or from budgeted to actual):

  • Weather: Especially because of volatility in demand charges, costs are highly responsive to hot weather.
  • Rate: Utilities tend to raise rates year after year, and the intersection of time-of-use effects with individual energy use patterns results in unpredictable changes to your bill.
  • Calendar: Bill period length can vary by 10% or more, and the exact number of weekends and holidays in a billing period show up in your costs.
  • Operations: Once all the other sources of variation have been accounted for, operations is what’s left over. This category includes everything from occupancy effects to events to equipment failures.

The beauty of an energy model is that it can isolate the signal from the noise, breaking down variance according to source. The bill data up above is collected and presented in Gridium’s Billcast product, which also performs variance analysis. Billcast automatically corrects for the uncontrollable (weather, rate, calendar), showing exactly what portion of the year-on-year variance should be ascribed to operations:

Phew! The nightmare is now over. After correcting for weather, rate and calendar, the project is saving even more than expected. Join me in feeling the relaxation flow though your body as you calmly drop the numbers into an email to your asset manager.

Variance reporting is part of our Billcast product and quickly becoming a most favorite feature among customers.

About Tom Arnold

Tom Arnold is co-founder and CEO of Gridium. Prior to Gridium, Tom Arnold was the Vice President of Energy Efficiency at EnerNOC, and cofounder at TerraPass. Tom has an MBA from the Wharton School of Business at the University of Pennsylvania and a BA in Economics from Dartmouth College. When he isn't thinking about the future of buildings, he enjoys riding his bike and chasing after his two daughters.

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