##  [Heating Degree Days](/heating-degree-days) 

  ##  [Heating Degree Days](https://engineering.quantumdictionary.io/heating-degree-days-0) 

  

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**Engineering & Applied Technologies Dictionary**

 







 

 

 

 



 

 

 

 

Definition

A cumulative climate metric equal to the sum, over a period, of daily contributions when the daily mean outdoor temperature is below a chosen base temperature; each day's contribution equals (base temperature − daily mean) when positive. Used as a first‑order proxy for building heating demand under standard assumptions.