Here in Tulsa, we haven’t had a day with a high below ninety degrees since June 21st! That means that our air conditioners have been on full blast, and cooling costs are rising right along with the mercury in the thermometers outside. But how much is this actually costing homeowners? Are these costs on par with years past? What level of efficiency is your air conditioning unit running at, compared with prior summers?
An easy way to answer all these question and more is by calculating heating degree days in your area. Heating degree days are a statistic that helps us identify how many times, and how far the outside temperature has gone over 65 degrees in a given time period.
There are very complex, and relatively simple ways to calculate heating degree days. Our experts use many factors in order to get this number exactly right. The simplest way, however, is to take the high and low for each day in your time period, add them together, divide by two, and then subtract the 65. So, for example in Tulsa earlier this week:
· if the high was 107 and the low 83,
· then together they are 190
· then divided by two, they are 95
· And since 95 is exactly 30 degrees above 65 (standard baseline)
· That means yesterday saw 30 degree days.
Now, one day of figures isn’t especially exciting, nor is the prospect of calculating a whole month or year. Thankfully, there are convenient websites out there like here, where you can calculate huge time periods. With the total number of heating degree days in 2010, for example, you can compare that number to how much you spent on cooling costs that year. Then, you will know how much you spend cooling your home for every degree that outside temperatures go above 65.
Now, compare these numbers with your friends and neighbors, see who has the lowest cost per degree day, and you’ll know who’s saving the most money, and who needs to call in the experts.
Our goal is to help educate our customers about energy and home comfort issues (specific to HVAC systems). For more information about degree days and other HVAC topics, download our free Home Comfort Resource guide.