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Advanced Wall Assemblies

What are Heating Degree Days?

The concept of “Heating Degree Days” was developed as a way to measure a building's heating energy demands on a daily basis.

To calculate heating degree-days one would average the high and low temperatures for the day, and then subtract the average from 18ºC.

Environment Canada’s example shows, “a day with a mean temperature of 15.5 has 2.5 heating degree days”; 18°C - (+15.5ºC)= 2.5; “a day with a mean temperature of 20.5°C has zero heating degree-days.” If every day in a 30-day month had an average temperature of 15.5ºC, the month’s HDD value would be, 75 (2.5x30).

Effective R-Value insulation requirements for buildings is determined by heating degree-days. Heating demands for a home in Winnipeg MB would obviously be greater than for a home in Victoria B.C. However, regardless of the building's HDD location, the amount of insulation in the building's envelope plays a major role in reducing the building's energy demands for space heating.

As shown in the map below, Canada is separated into five zones ranging from <3000 to ≥7000 heating degree-days. Insulation requirements for buildings in zone eight would be greater than for buildings in zone five.


 

 


 

 

Note: Flashing strip required at the bottom of the wall.

  
   

 

Notes: Drainage plane required for coastal regions only. If connect is installed against the sheathing, housewrap may not be required. Check local building codes.  Bug screen required between rain screen strips. Flashing strip required at the bottom of the wall.

  

 

Notes: Drainage plane required for coastal regions only. If connect is installed against the sheathing, housewrap may not be required. Check local building codes. Bug screen required between rain screen strips. Flashing strip required at the bottom of the wall.


   

 

Notes: Drainage plane required for coastal regions only. If connect is installed against the sheathing, housewrap may not be required. Check local building codes. Bug screen required between rain screen strips. Flashing strip required at the bottom of the wall.

 
   

 

Note: Flashing strip required at the bottom of the wall.

  
   

 

Note: Flashing strip required at the bottom of the wall.

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