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Cooling Degree Days

Description: 

Degree days estimate the amount of heating and cooling needed to maintain a comfortable interior environment. Hot days, which may require energy for cooling, are measured in cooling degree days. Cold days are measured in heating degree days.  In order to calculate cooling degree days, a reference temperature of 65°F is subtracted from the daily mean. The sum of the differences between the daily mean temperatures and 65°F equal the cooling degree days for the month.

An increase in the number of cooling degree days leads to increased energy demand used to cool building interiors. With higher energy costs in the summer, this has an economic impact. With increases in minimum temperatures, energy demand further increases with almost continuous running of air conditioning units.

Data Source: 

Data were collected from NOAA's National Climatic Data Center, Satellite and Information Service. [http://www.ncdc.noaa.gov/cdo-web/results], Phoenix Sky Harbor International Airport

iconNumber of June Cooling Degree Days for Phoenix

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Visualization Notes:

Cooling degree days have increased greatly since the mid-20th century. This is likely due to increases in higher nighttime temperatures, an effect of the urban heat island. This graph shows cooling degree days for the month of June in the years 1948 through 2013. Temperatures were recorded at the Phoenix Sky Harbor International Airport climate monitoring station.

Data Source

Data were collected from NOAA's National Climatic Data Center, Satellite and Information Service. [http://www.ncdc.noaa.gov/cdo-web/results], Phoenix Sky Harbor International Airport