What’s in a day — a degree day, that is?

Degree days are commonly used to measure how warm or how cold it is over a given period of time. They can be used to help track heating and cooling costs, estimate future costs, detect problems like a failing heating system, and track the savings achieved by energy-saving measures.

A degree day is calculated as the difference between the average daily temperature and a basis temperature of 65 degrees. Degree days can be measured over any period, including a day, week, month or year. Higher heating and cooling degree days generally mean higher heating and cooling costs.

Our Energy Analyzer click here allows you to track heating and cooling degree days and see the effect on your electricity usage. You can:

* View a graph of your usage against degree days for the past two years. 
* Determine the total number of heating and cooling degree days for a given billing period. 
* Compare kilowatt-hours per degree day for different billing periods.

Giving you access to this additional usage information is what our e-power initiative is all about. To begin exploring the Energy Analyzer today, click here. If you’re a first-time user, you’ll need to create a new user name and password and register your account. After that, you can return at any time by simply logging in.

How to calculate degree days

Heating degree days
If the low temperature for the day is 10 degrees and the high is 30 degrees, you would calculate the heating degree days by

1. Adding the low and high temperatures together and determining the average — in this case, 20 degrees.
2. Comparing this average to the norm of 65 degrees. In this case, the difference is 45 degrees, so 45 heating degree days result.

Cooling degree days
If the low temperature for the day is 60 degrees and the high temperature is 90 degrees, you would calculate the cooling degree days by:

1. Adding the low and high temperatures together and determining the average — in this case, 75 degrees.
2. Comparing this average to the norm of 65 degrees. In this case, the difference is 10 degrees, so 10 cooling degree days result.