CoolCalc uses design conditions specified in ACCA tables. It's important to note that heating and cooling design temperatures are not the most extreme temperatures that may occur in your area but rather the typical high/low temperatures that HVAC systems should be designed for in your area. ACCA design temperatures are updated approximately every 5 years.
Cool Calc will automatically select the closest weather station to the home based on distance. However, it will present the user with the nearest five stations in case there is one that more accurately reflects the temperatures for that area. You may override the ACCA specified design temperatures only if local building code allows.
Heating Design Temperature – In the winter, the temperature should remain above this value 99% of the time. This value is automatically populated based on the weather station selection, but can be overwritten.
Cooling Design Temperature – In the summer, the temperature should remain below this value 99% of the time. This value is automatically populated based on the weather station selection, but can be overwritten.
The indoor design temperatures are set to 75 degrees in the summer and 70 degrees in the winter.