Estimate cooling degree days from daily high temperature, daily low temperature, base temperature, number of days, and previous accumulated CDD. This calculator is useful for cooling demand estimates, air conditioning planning, utility comparisons, and seasonal heat tracking.
High and low temperature:
Enter the daily maximum and minimum temperature for the day or period you want to estimate.
Base temperature:
The base temperature is the outdoor temperature above which cooling is assumed to be needed.
Daily CDD:
The calculator averages the high and low temperature, then subtracts the base temperature from that average.
Accumulated CDD:
The calculator can multiply daily CDD by a number of days and add previous CDD to estimate a seasonal total.
A cooling degree days calculator is useful for estimating air conditioning demand, comparing hot weather periods, reviewing utility bills, tracking summer heat, planning cooling loads, and comparing seasonal weather patterns.
This is a rough weather-based estimate. Real cooling energy use depends on building size, insulation, air leaks, thermostat settings, cooling system efficiency, humidity, sun exposure, occupancy, and local conditions.
Your result shows estimated cooling degree days for one day, the selected number of days, and the total after adding any previous accumulated CDD. Higher CDD values usually mean hotter weather and greater air conditioning demand.
Average the daily high and low temperature, then subtract the base temperature from that average. If the result is below zero, daily CDD is usually counted as zero.
65°F is commonly used in the United States for cooling degree days, but some buildings or analyses may use a different base temperature.
In most CDD tracking, negative values are set to zero because cool days do not subtract from accumulated cooling demand.
No. CDD is a weather-based estimate. Actual energy use also depends on the building, air conditioning system, thermostat, insulation, humidity, sun exposure, and occupant behavior.