It has been said that man's mastery of the world began when he stopped guessing and began measuring.  The measurement of distance has come a long way since ancient Egyptian days.  In those days the forearm was the standard of measurement used to construct the seemingly time resistant Pyramids.
    Degree days are important to fuel oil dealers because this measurement allows them to deliver greater quantities of fuel at lower costs than by any other known method.  Since development of degree days around 1930, the term "degree day delivery" has become a common expression.
    Degree days are conventionally defined as the difference between 65 degrees Fahrenheit and the daily mean temperature.  Studies show that in general no fuel will be used for space heating when temperatures are above 65 degrees Fahrenheit.  This fairly well establishes 65 degrees Fahrenheit as a proper starting point.
    However, as man required more accuracy to do a better job, the forearm of the Egyptian gave way to precise instruments of our present day.  Likewise, as more accuracy in measuring fuel consumption would allow dealers to make larger drops and increase profits, it is only natural that a better method of measuring fuel consumption be developed.
    Before discussing a better method, let's evaluate our present method of measuring fuel consumption.  Conventional degree days usually do a satisfactory job during cold months.  In mild weather however "something happens."  For example, the temperature may climb to 80 degrees Fahrenheit for a short time then drop to 50 degrees Fahrenheit during most of the night.  On this day the mean temperature is 65 degrees Fahrenheit, therefore no degree days.  A thermostatically controlled building or home will use fuel during the time the temperature is below 65 degrees Fahrenheit, while our mean temperature degree days indicate no fuel has been used.  Conventional degree days are almost useless in such a case.
    Another example of inaccuracy develops during periods of hotter than normal wind conditions.  Various reports indicate that considerable more fuel is used when the wind is blowing than when it is not (other weather factors being the same).  This becomes particularly noticeable on accounts with short delivery schedules as it can be windy during the entire period between deliveries.  This causes k-factor fluctuation: result, we have to schedule smaller deliveries in an effort to avoid run outs.
    There are other factors which influence fuel consumption that cannot be accounted for by conventional degree days.  One is the effect of sunshine.  A solar heated home points out this effect, and when temperatures rise or drop sharply and remain at either of these points during most of the 24 hour period.
    In many cases k-factor fluctuation is thought of as just "one of those things."  People change their heating habits, play with the thermostat or other factors are attributed to k-factor fluctuations.  There is merit in these arguments.  However, people (customers) do not change their ways once they have established them.  Your credit department can verify this.
    Many degree day operators know that these conditions exist and apply corrections to help offset the k-factor fluctuations.  One obvious method is to take an average temperature rather than a mean temperature.  However, getting an hourly reading is sometimes difficult and when the temperature exceeds 65 degrees Fahrenheit the hours below 65 degrees Fahrenheit need to be prorated, necessitating perhaps an hour's work, not to mention the chance of serious error.  Another method is "brute force" correction.  This is done by shortening the delivery schedule during mild weather, so that even if degree day information is off by 30% or 40%, customers won't run out - "dries" as they are referred to in Brooklyn.  With this method, the size of the drop decreases, which means operating expenses increase, customers are happy but profit takes a nose dive.
    With positive degree day information - degree day information which compensates for wind, sun and mild weather conditions - the size of drops can be increased.  If 90% of your customers' k-factors fluctuated by less than 10%, then you could safely plan 210 gallon drops to 275 gallon tanks and know that the drop would be between 191 gallons and 231 gallons.  No run outs would result and a substantial delivery made.
    Here is what would happen on an account using 1,500 gal. per year of fuel oil if we increased our drop size to 18% to 210 gals.  This account would require approximately 8.1 stops per year delivering 185 gallons per stop.  At 210 gallons per stop, this account would require approximately 7.1 stops per year, or one less stop.
    Not much of a saving!  Take another look.  You probably have a fair idea of what it costs to make a typical delivery.  Multiply this by the number of accounts you have and the result is a sizable sum, most of which represents net in terms of profit.  It takes just a few seconds more to pump the additional gallons, but compared to driving time, dispatching time, pulling hose, etc. there is no more time involved in making the stop with the increased size of delivery.  This is especially true with the increased pumping speeds many companies are now employing.
    It is obvious that with more accurate degree day information, profits can be increased.  With this in mind, the Fuel Demand Meter was developed.  It determines the average daily temperature by "integrating" sub 65 degrees Fahrenheit temperature.  By proper design it was possible to make the meter account for increased fuel consumption caused by wind and decreased fuel consumption caused by the effect of the sun's radiation.  These effects are in direct proportion to fuel consumption.  The extent to which the meter accomplished its purpose can be judged from the following reports and data.
    A group of ten typical accounts were selected at random from our Kalamazoo, MI fuel oil operation's degree day files.  Each had at least one delivery per month beginning in october.  The factors of all houses were average for each month and compared.  The maximum k-factor variation from average was plus or minus 2%.
    Within a four mile radius of Kalamazoo there are three official weather stations.  Two of these stations, including the official State station, are within two miles of our bulk plant and meter.  All stations are within our delivery area.  On a cold day it is not unusual for the weather stations to have as much as an eight degree difference in the reported low temperature.  It is evident that temperature variations exist in this area.  Under these conditions the Fuel Demand Meter indicated accuracy within plus or minus 2%.
    With accurate degree day information, fewer run outs occur, less clerical time is needed to make corrections, and larger drops can be planned.  Yes, dollars and degree days.