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# What does this mean?

Member Posts: 7,607
edited July 2019
I am doing some light reading in the 2018 IECC https://codes.iccsafe.org/content/IECC2018P3/chapter-4-re-residential-energy-efficiency

Does anyone know what this part of Table 405.5.2(1) means?

I keep coming up with millions of Btu/day for a 1,000 square foot home. That can't be right...
"If you can't explain it simply, you don't understand it well enough"
Albert Einstein

• Member Posts: 6,505
1000 sq ft and 3 bedrooms = 54012
=17900 + (23.8 x 1000) + (4104 x 3)
=17900 + 23800 + 12312
=54012

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• Member Posts: 15,886
forgot what that's called .............order of...........something
• Member Posts: 23,753
I have to admit that the way it's presented isn't perfectly clear... @STEVEusaPA 's parentheses are correct -- but it would be better if the publisher had put them in in the beginning, because @Zman 's interpretation isn't actually incorrect, considering just the way it's written, either.
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
• Member Posts: 7,607
Thanks @STEVEusaPA
I guess you need to go to the IMC before they will trust you with 8th grade algebra order of operations
"If you can't explain it simply, you don't understand it well enough"
Albert Einstein
• Member Posts: 6,505
edited July 2019
👍
It’s actually correct the way it’s written. When no parenthesis are written, order of operations are the rule.
Just think of a formula with no parenthesis like:

π r^2
You would square the radius before multiplying π.

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• Member Posts: 22
Hey, at least he knew enough to know something was wrong....

Unlike some fresh-outta-school engineers I have met.

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• Member Posts: 1,458
I came up with 54,600 for my house. Which works out to be 2,277 btu's per hour.Interestingly, the formula assumes all the bedrooms are occupied to get that reading. That would have to be something to factor in if you were trying to get a very accurate heat loss of the house.
Rick
• Member Posts: 7,607
LuckyDog said:

Hey, at least he knew enough to know something was wrong....

Unlike some fresh-outta-school engineers I have met.

I had an "AHA" moment as soon as @STEVEusaPA pointed it out. The class where I learned order of operations was more than a few years ago
"If you can't explain it simply, you don't understand it well enough"
Albert Einstein
• Member Posts: 6,505
I wonder how the kids solve that equation with the new style math?

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• Member Posts: 3,714
"Siri whats the ansrwe"?