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Anyone understand r-value math?


Zero Knievel

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Trying to determine how efficient/effective the house windows are.  Outside temp 26 F.  Indoor air temp 69 F.  Inside glass pane 51.9 F.  Outside glass pane 34.3 F.  From what I know, double pane windows usually have an r-value of 1-2 on average.

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4 hours ago, DBLXX said:

Nope, that’s the one. 

Being that it maxes out at 1 and insulation R value goes way above that, it appears that the R value of your video is about 0.

 

Mike, I don't know if this will answer your question, but it has a better chance: https://en.wikipedia.org/wiki/R-value_(insulation)

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I know what r-value means, but how does one determine it from just temperature readings…if it’s possible?  Most of the math is way over my head.  I was hoping there was a calculator that could guesstimate r-value based on inputting the outside and inside surface temp of a material or structure.

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17 minutes ago, Zero Knievel said:

I know what r-value means, but how does one determine it from just temperature readings…if it’s possible?  Most of the math is way over my head.  I was hoping there was a calculator that could guesstimate r-value based on inputting the outside and inside surface temp of a material or structure.

 

Outside of a controlled lab environment, no way to do this reliably.  You'd have to factor in all sorts of other things like air movement, and reliably read one square meter.  I think our insulation could use improvement for summer heat, so I'll rent/buy a FLIR to scan the whole house.  Then put it on the quadcopter to scan the roof.  

 

 

 

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23 hours ago, Zero Knievel said:

I know what r-value means, but how does one determine it from just temperature readings…if it’s possible?  Most of the math is way over my head.  I was hoping there was a calculator that could guesstimate r-value based on inputting the outside and inside surface temp of a material or structure.

Beyond what Carlos said, accurately measuring the temp of glass seems impossible to do with household equipment.

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...at night best.

 

The cardboard is a good idea. You could check the difference at night fr fun.

 

...cardboard just big enough to keep the sun off the plastic container and not insulate the whole window. 

 

Really light weight so mass is less of an effect.

RD-CS-16_330.jpg

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On 2/5/2022 at 5:21 AM, Zero Knievel said:

Outside temp 26 F.  Indoor air temp 69 F.  Inside glass pane 51.9 F.  Outside glass pane 34.3 F.  From what I know, double pane windows usually have an r-value of 1-2 on average.

That can be modeled with the right software.

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