What are Heating Degree Days?
During the hotter months we accumulate cooling-degree days, an indicator of how much energy was required to cool a home or business. During the colder months we accumulate heating-degree days, an indicator of how much energy was required to heat a building. Degree days are proportional to heating and cooling costs. They are calculated by adding the actual high and low temperature for one day together and dividing by two. This gives you the average temperature for the day. Subtracting the average temperature from 65 gives heating degree days; subtracting 65 from the average temperature gives cooling degree days. By the way, there were just six days of measurable rainfall in Charlotte during the month of May.
Heating degree days (HDD) are a formula that actually represents how hard you may expect your furnace to work that day. The greater the number of heating degree days, the more the furnace must work in order to keep the inside environment comfortable. The formula is very simple both for heating degree days and cooling degree days. However, with cooling degree days, the formula is reversed. The way to find out the number of heating degree days is to take the high temperature for the day and add it to the low temperature for the day. Once that is done, then divide by two. For example, if the high one day is 50 degrees Fahrenheit (10 Celsius), and the low is 32 Fahrenheit (0 Celsius), the average temperature would be 41 Fahrenheit (5 Celsius). This average Fahrenheit temperature would then be subtracted from 65 Fahrenheit (18 Celsius). This temperature was chosen as a comfortable temperature at which additional heating is no longer needed. The result would be 24 heating degree days for tha
Heating Degree Day (or HDD) is a unit that helps us understand how much energy must be used to heat (or cool) our homes to a comfortable level. It is assumed that 65° Fahrenheit is a comfortable indoor temperature. So, if the outdoor temperature is colder than 65°, then you will need to use some energy to heat your house up to that 65° level. The number of HDD will indicate how much energy you will need to use. The formula for determining HDD is simply subtracting the average outdoor temperature for the day from 65. It looks like this: HDD=65-T, where T indicates the average outdoor temperature. T is determined by simply taking the high temperature for the day, adding it on to the low temperature for the day, and dividing by 2. It looks like this: T=(high temperature + low temperature)/2. The higher the HDD, the more heat it took to heat your home to a comfortable level. The lower the number, the less heat. You can tell if you are using more or less energy during the winter by checking
