ENERGY STAR ratings, month by month

Energy Stewards® creates summary graphs and tables from your building’s monthly energy use data.  These monthly values, shared with the ENERGY STAR system, are the starting point in understanding the energy performance of your building.

Let’s take a look at the electric and gas use charts from an office building in Madison, WI.

These graphs show a very strong seasonal pattern (for electricity–high in summer, low in winter; for gas, high in winter, low in summer).  It looks like the seasonal peaks (the summer highs for electricity use and the winter highs for natural gas use) are coming down over three years.   That’s a good thing.  Still,  the monthly values jump around a little bit, even if you keep the seasonal pattern in mind.   Is there really improvement in energy use?

A skeptic might wonder whether the apparent improvements stem from milder weather or a decrease in hours of operation.

ENERGY STAR® ratings, graphed month by month, provide an answer. Energy Stewards communicates with ENERGY STAR and captures your building’s ENERGY STAR® ratings.   Energy Stewards then graphs the ratings, month by month, as well as the 75 level cut point to achieve an ENERGY STAR award.   Here’s a graph of ratings of the same office building:

This graph tells a simple story:  steady improvement in energy performance over the past three years; the building is very close to the 75 rating, marked by the green line.

Remember that each month’s ENERGY STAR rating totals up all the energy used by the building over the previous year, and then adjusts for weather and attributes specific to the building type.  For example, an office building needs to track size in square feet, the number of employees, the number of hours of operation and the number of personal computers in use.  If any of those attributes change during the year, ENERGY STAR takes those changes into account.

Of course, if you or your group administrator don’t keep your building’s information up to date in ENERGY STAR Portfolio Manager, the ENERGY STAR ratings won’t give you the appropriate message.

So, keep an eye on ENERGY STAR ratings over time displayed on the Detailed Energy Use page. And keep your building attributes current.  You’ll have a solid basis for judging energy performance.

WHAT IF YOUR BUILDING IS NOT RATED?  As of 31 March 2012, ENERGY STAR provides ratings for 15 types of facilities.  If your building is not rated, Energy Stewards plots monthly weather-adjusted energy intensity.  This number is a simplified version of an ENERGY STAR rating–it only takes into account weather and square feet of the building. Like the rating, the weather-adjusted energy intensity is a rolling 12 month total.  Here’s an example of this measure for a building that is mostly manufacturing and repair shop:

The impression again is of a big improvement in energy use.  Now, it could be that the facility had a drop-off in business in 2010 and 2011, thus accounting for the decrease.  We asked that question–and in this case, their business did not drop off, they really did decrease energy use.

REMINDER ABOUT ENERGY STEWARDS GRAPH SYMBOLS  What are those green triangles on the graph?  Remember that the triangles represent actions taken by the building users and facilities staff to reduce energy use.   If the actions are effective, we expect to see actions line up in time with reduced energy use, like we see in our example.  When you are working in Energy Stewards and the graphs are “live”, you can click on each triangle to see the list of actions associated with the month aligned with the triangle’s downward facing vertex.

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