What's the correct ODT?

28W

I live about 12 miles west of Boston. I've seen Boston ODT of 7 degrees, and also 0 degrees. What number do the pros use when doing heat loss calculations? Thanks

Empire_2

Local weather for ?

Every state has (from the national average degree days) available from its local weather records, statistic archive from the past 10 years+.  Although climates do change, the information is our basis for the factor of degree day.  Anyone interject if different.  Google Degree day for -state......



Peace;



Mike T.

Jean-David Beyer

I've seen Boston ODT of 7 degrees

I do not know what the professionals use, since I am not one of them.



But this homeowner used a chart from Weil-McLain for computing these things, and they give an outdoor design temperature of +9F for Boston, Massachusetts.  For my part of New Jersey they give +14F.



I lived in Boston a long time ago, and it was much warmer than Buffalo, NY, that is +6F. In the 25 years or so I lived there, it got down to -10F one night. But that was unusual. Toronto Canada is much colder, -10F. My niece lives in Edmonton, Alberta and it is -26F. Glad I do not have her heating bill.



Of all the places I never lived, this



https://en.wikipedia.org/wiki/Verkhoyansk



is the winner in the places I would never even want to visit contest. I learned about in in a Geography of the Soviet Union course I took long ago. When the make a street there, they dig a ditch the width of the road to be, dump in crushed rock,  then a foot or so of sawdust with a steam pipe (uninsulated), a water pipe, and a sewer pipe. The steam is to keep the other two from freexing. They then dump in more sawdust and more crushed rock up to grade. The road is paved with wooden planks. It is the only satisfactory construction material in those conditions. Record cold was -93F and the record hot was +103F. Asphalt and concrete do not survive the extremes.