Degree days, how much oil do you use?

Grab your cell phone. (I’m sure it has a calculator, right?) We’re going to calculate degree days. What are they? Well, years ago heating engineers wanted a way to relate each day’s temperatures to the demand for fuel to heat buildings, so they developed the concept of heating degree days (HDD). Very simply, heating degree days are a measure of how much (in degrees), and for how long (in days), the outside air temperature is below a certain level.  They are commonly used in calculations relating to the energy consumption required to heat buildings. Knowing this will help you determine if the money you spent on adding that extra insulation is paying off (link to conservation post). With your records of past heating oil usage you could just do the calculations and make the comparison. Degree days can also help you know how much more or less you might spend on heating (or air conditioning) if you move to another part of the country. (Genie would miss you, of course!)

Here’s how it works. To calculate the heating degree days for a particular day, find the day’s average temperature. If the number is above 65 (base temperature for comfort), there are no heating degree days that day – the HDD = 0. If the number is less than 65, subtract it from 65 to find the number of heating degree days. Here’s an example: if the day’s high temperature is 60 and the low is 40, then the day’s average temperature is 50 degrees. 65 minus 50 is 15 heating degree days (HDD).

So, what does that mean? When you add the HDDs together for the month, say 15 on October 1st, 16 on the 2nd etc., you’ll then have a total for the month (or any time period you choose) to compare to previous years. For example, the annual average HDD for Barrow, Alaska is 20,370 versus 934 for Yuma, Arizona. Who has the cheaper heating oil bills? Yup. Arizonans. I bet you knew that without your calculator didn’t you.

Okay, now that you know how to do it yourself, there’s a website that will calculate it for you. (Now, now. Don’t start throwing things at your favorite Genie!) Check it out here .

Pick up your calculator:

Take your degree days for last winter(from website above) and divide by the amount you spent on heating oil for that same time period and you’ll have a baseline from which to calculate your energy-saving improvements, regardless of whether it’s warmer or colder this year.

Example: (From BWI data for winter 2014-15)

5481(HDD) / $2500(Oil costs) = 2.19

If you are really interested in measuring the improvements you’ve made in insulating your home and how much you’re saving on home heating oil expenses, the Degree Days site has plenty of resources for you, too.

As always, Genie is here to help you save on your heating oil costs. For cheap heating oil prices and delivery information, go to today!