Heating and Cooling Degree Days explained

It's a matter of degrees
Recommended thermostat settings are 78 degrees in the summer and 68 degrees in the winter.

NORTH TEXANS love a nice, 65-degree day.

It’s not too hot that you need your air conditioner or too cold to need the heater.

The more the temperature goes above or below 65 degrees, the more energy it takes to keep the indoors comfortable. How long the temperature remains that high or low is also a factor.

That’s the basis of the Cooling Degree Days (CDD) and Heating Degree Days (HDD), a metric that CoServ and other utilities use to help predict energy demand.

As your trusted energy advisor, CoServ wants to show Members and Customers how they can calculate CDDs and HDDs to predict past and future energy usage.

The first step is to find the average temperature for the day. CoServ uses the National Weather Service's Fort Worth office for consistency. If the value is above 65 degrees, you will subtract 65 from it to find the CDD. If the average is below 65 degrees, you will subtract the average temperature from 65 to find the HDD.

Here are some examples using the hottest and coldest days from 2023.

CDD August 2023

On August 25, 2023, the average temperature in North Texas was 98 degrees.

98 - 65 = 33 Cooling Degree Days

The CDD for August 2023 totaled 872, which was 229 CDD above normal, according to the National Weather Service. That’s the second highest CDD recorded for a month behind only August 2011, which explains why electricity usage was so high for that month.

HDD January 2024

The coldest day was January 15, 2024, when the average temperature was 19 degrees.

65 - 19 = 46 Heating Degree Days

The HDD for January was 674, 92 HDD above normal, which explains why Members and Customers had high bills for that month.

Understanding the relationship between weather and energy usage can help CoServ Members and Customers make smart decisions during extreme weather and, ultimately, save money.

Visit CoServ.com/WeatherStats for the latest information on weather and its effects on your bill.