Understanding Residential Energy Consumption
Some years back my company began to "double meter" some of our new homes. We wanted to understand how homes consumed energy in the north central Texas area. Our goal was to make our homes more energy efficient and to do so we needed to know where the energy was being consumed.
What Is a "Base Load?"
We installed the second meter between the regular electric company utility meter and the heating and cooling equipment. Our meter only showed us how much energy was being used to heat and cool our homes. By subtracting our meter reading from the overall utility reading, we found out how much power is required to run the lights, refrigerator, freezer, dryer, hot water, and everything else that isn't part of the heating and cooling equipment. We call the power needed to run everything but the heating and cooling equipment the "base load" of a home. The monthly base load represents all the energy used to run a home each month except for heating and cooling.
After monitoring these homes for several years, we made several interesting and important revelations. Each month the power consumption by the rest of the house (base load) remained fairly constant throughout the year. People tend to use about the same amount of hot water, lighting, etc., every month.
Texas Does Have Spring and Fall!!
We also found that almost always there was a month in the spring and fall when the meter on the heating and cooling equipment moved very little or not at all. With the mild spring and fall weather, the heating and cooling equipment wasn't being used. This meant the utility company meter reading was identifying the base load. Suddenly we realized that we could figure out the base load of a home without the second meter.
Our Discovery Goes to Work
We realized that if you looked at a 12 month history of the utility bills, the lowest monthly reading (almost always a fall or spring month) could be called the monthly base load of the house. That was a month that the heating and cooling was used very little if at all.
FYI: If you use gas, your gas base load is usually during the summer.
You Can Do It, Too
Now all we had to do was to request a 12-month history of utility bills on any home and we could understand how that home performed. For the past five years, each of our homebuyers signed a letter to their utility company giving us permission to request a history of their utility bills for monitoring purposes. You can receive your own utility history from your utility company-just call and ask!
A Real Example
Below is a copy of some of the data you will find on your utility history printout. This is actual data from a home we built several years ago. This year the heating and cooling bills on this home were a little higher than in past years. Of course when you look at this past summer's record number of days of over 100 degrees, it is still pretty good. This home is all electric and has 2340 square feet of heated and cooled area. It is located just north of Waxahachie.
