Like many of you, I'm certainly glad to see Spring finally arrive.  After experiencing two major ice storms in the past two years, your Cooperative was relieved that we did not have to encounter another major ice storm this winter.  Although we did not encounter a major ice storm, this winter proved to be one of the coldest winters in quite some time.  The cold winter months resulted in most residential services consuming near record energy consumption resulting in higher electric bills.  I would like to take this opportunity to help explain why many residential and business services experienced higher than average energy consumption in the first few months of 2010.

       Utilities consistently monitor temperatures to help determine the necessary demand for energy but heating degree days is an index that quantifies the demand for energy needed to heat a specific structure, such as a home or business, during the winter months.  A similar index, cooling degree days, is used to help determine the demand for energy to cool a structure in the summer.

       Heating degree days is calculated by taking the average base temperature that a specific structure is normally heated to minus the average outside ambient temperature for each day of the month and then adding all days in that specific month.   Many would think that the base temperature would be around 70°F but for historical reasons and the availability to compare this index over a long period of time, the base temperature is normally defined as 65°F.  In order to calculate this index, assume the average outside ambient temperature for the 1st day of the month is 30°F.  The number of heating degree days for the 1st day of the month would be calculated as 65°F - 30°F = 35 heating degree days.  Assume the average outside ambient temperature for the 2nd day of the month is 25°F.  The number of heating degree days for the 2nd day of the month would be calculated as 65°F - 25°F = 40 heating degree days.  You would continue this process for each day of the month and then add all the respective heating degree days for the entire month.  The following is a table that shows historical values for the heating degree index in Southern Illinois.

                                                               

       As stated earlier in the article, the months of January and February of 2010 proved to be very cold months with colder than average temperatures.  As you can see in the previous table, the heating degree days for the month of January 2010, as measured in Southern Illinois, equaled 1,162.  The average heating degree days for the previous five years in the month of January is 905.9.  This means that January 2010 had heating degree days that was 28.3% higher than the previous five year average.   For the month of February 2010, the heating degree days equaled 975.  The average heating degree days for the previous five years in the month of February is 822.6.  This means that February 2010 had heating degree days that was 18.5% higher than the previous five year average.  As you can also see in the table, the heating degree days in January and February of 2010 exceeded all months in the previous five year period.

       This information is helpful in understanding why most residential customers experienced higher energy consumption in the first few months of the year 2010 and subsequent higher energy bills.  The electric bills are higher than average due to the colder temperatures we have encountered, equating to higher heating degree days which required the heating systems in our homes and businesses to run longer, consuming more energy than they normally would have.  This higher energy consumption would even apply to homes or businesses that heat with propane or natural gas.  In this case, although the primary source of heat is not electricity, electricity is required to operate the fans and blowers to distribute the heat throughout the homes and therefore would still require more electricity to operate.

       With Spring finally here, hopefully we have seen the worst of the cold weather for a while and we can all enjoy milder weather conditions and subsequently lower energy consumption.

See you next month and as always, "We'll keep the lights on for you."

Month	2005  2006  2007  2008  2009	5-Year Avg.	2010     % Above Avg.
January	828    694    904    995  1110	906	1162           28.3%
February	653    857    964    897    744	823	975           18.5%