6.1.1 Describe heating degree days

• The sum of the number of degrees that each day's average temperature is below 65° Fahrenheit (18° Celsius) for one year.
  
  • A HDD = 65°F(18°C)-daily temperature mean((high temperature + low temperature)/2)
    
  • if you have multiple days that you are calculating, you will complete this equation for each day and sum the total HDD
    
  • Example: calculate the heating degree days when the mean temperature for a 5 day period in Celsius is as follows:
    
    • -10.6, -15.4, -8.6, 1.5, -5.4
    • Convert to Fahrenheit (multiply by 1.8 and add 32 )
    • Apply equation
      • =(65-12.92) + (65-4.28) + (65-26.52) + (65-34.7) + (65-22.28)
      • =52.08+60.72+38.48+30.3+42.75
      • =224.33 HD
• Total number indicates the relative severity of winter for a specific location
• Windsor 3525; Ottawa 4600; Timmins 6149 used for past 10 years
• Now 3400; 4500; 5940