1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Very Quick U Value Question

  1. Jul 23, 2009 #1

    My first post! Thank you for any replies!

    When looking at U values for windows (= 1/R) they are 99% of the time in the units

    W/(K*sq meters)

    A certain manufacture has their units in

    W/(sq meters)/(degree C)

    Now, the degree C to Kelvin should have no effect on my calculations (because the Heat flow formula subtracts temp), but the fact that the temperature unit is being divided twice (or just multiplied) instead of just being divided causes me some worry.

    Has anyone seen this before, can you convert from the bottom units to the top? Do you think its just a mistake?

    The bottom units have unusually small U values compared to the normal.

    Thank you!
  2. jcsd
  3. Jul 23, 2009 #2


    User Avatar
    Science Advisor

    What does "W/(sq meters)/(degrees C)" mean? That's just bad notation. It could mean either "W/[(sq meters)/(degrees C)]" which would be better written "[W(degrees C)]/(sq meters)", which seems to be they way you are interpreting it, or "[W/(sq meters)]/(degrees C)" which would be better written "W/[(sq meters)(degrees C)]" and is probably what was intended.
  4. Jul 23, 2009 #3
    Thank you for your reply!

    Sorry, thats how I typed it, here is how they have it


    But you think they mean

    (W/m²*C) ?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook