ELI5: Explain Like I'm 5

Heating degree day

When it gets cold outside and we have to turn on the heat to make our house cozy and warm, we use something called a heating system to make our house warm. This heating system uses energy to create warm air that spreads throughout the house.

Now, imagine that we have a special thermometer that shows how many degrees colder it is outside compared to the warm and toasty temperature we have in our house. This is called the base temperature. For example, let's say that our house is set to 72 degrees Fahrenheit and it is currently 32 degrees Fahrenheit outside. The difference between these two temperatures, which is 40 degrees Fahrenheit, is called the number of heating degree days.

So, if the temperature outside gets even colder, the heating system will have to work even harder to keep the house at the same warm temperature. This means that we will use more energy and more money to keep our house warm. That's why we need to keep track of how many heating degree days there are so we can plan and budget for the cost of keeping our house warm during the colder months.