TiToine a écrit:
Anyone knows how the Heat Deg Days and Cool Deg Days are calculated?
By definition:
HDD = Tmean - Tbase if Tmax > Tmean else 0
CDD = Tmean - Tbase if Tmin > Tmean else 0
Tbase = 18.3C or 65F
For
http://www.meteo-boisney.fr/NOAA/Septembre-2008.TXTIt seems the calculation work with HDD, but not with CDD.
Hi Antoine,
CDD =
TbaseCooling - Tmean if Tmin > Tmean else 0 // CDD are not negative
Usually, you should consider having a base for heating and a base for cooling (user definable), you do not cool if temperature is below 65°F, but you might heat.
Find herebelow the explanation given in VWS user's manual :
Degree Days Heating and Cooling
Because temperature plays an important part in the rate of development of plants and many pests, a measurement which takes into account the accumulation of heat with passing time is important to predict maturation. Degreedays provide a measure for calculating the effects of temperature on the development of plants or pests.
One degree-day is the amount of heat which accumulates when the temperature remains one degree above the threshold for one day.
One degree day is also the amount of heat which accumulates when the temperature is 24 degrees above the threshold for one hour.
Heating Threshold
The threshold for calculating degree-days heating.
Cooling Threshold
The threshold for calculating degree-days cooling.I hope this will help you.
They do not apply only to agriculture, as you may also use those to predict your heating and cooling electricity bill !