Revit Architecture Forum
Welcome to Autodesk’s Revit Architecture Forums. Share your knowledge, ask questions, and explore popular Revit Architecture topics.
abbrechen
Suchergebnisse werden angezeigt für 
Anzeigen  nur  | Stattdessen suchen nach 
Meintest du: 

Revit 2016 Heat Transfer Coefficient (U)

5 ANTWORTEN 5
GELÖST
Antworten
Nachricht 1 von 6
Anonymous
3543 Aufrufe, 5 Antworten

Revit 2016 Heat Transfer Coefficient (U)

to all.

im creating a few wall types for our office standards, going into the Wall assembly i found that i was able to add in the Heat Transfer Coefficient (U), however when revit takes into account all of the materials in the wall and adds up all of the U values  it doesnt match the numbers we get when we do the math manually, is there a way for me to locate the formula that revit is using to ensure that its adding things up correctly? or am i not doing something right?

 

thanks for you reply

 

James C.

5 ANTWORTEN 5
Nachricht 2 von 6
RDAOU
als Antwort auf: Anonymous

Hello @Anonymous

 

You are most probably doing it right. This is an old observation and the discrepency in calculated values appears to be due to the way cavities are treated by Revit in the wall layers. Example: Add the default "Thermal/Air layer" with a typical thickness 40mm and material set as "Air" is calculated in Revit as having a conductivity of 0.0250 W/(m·K) ie: the air cavity appears to have the same Thermal Conductivity/Resistance as a solid insulating material of the same thickness... If you are doing your manual calculation based on BRE standards; then you will find some discrepancies. (PS: I assume that if that discrepancy applies to air cavity it most probably applies to other material)

 

To solve that you will need to edit the xml file and enter your own U and R values as per the standard you need to follow. THIS POST HERE discusses this in detail and it might help you solve that issue.

 

https://forums.autodesk.com/t5/revit-mep/custom-construction-type-r-and-u-values/m-p/3412897/highlight/true#M15139

 

 

YOUTUBE | BIM | COMPUTATIONAL DESIGN | PARAMETRIC DESIGN | GENERATIVE DESIGN | VISUAL PROGRAMMING
If you find this reply helpful kindly hit the LIKE BUTTON and if applicable please ACCEPT AS SOLUTION


Nachricht 3 von 6
Anonymous
als Antwort auf: RDAOU

oh wow.. ok thanks for the tip ill dig my heels in and see if i can get this thing to work

 

regards

 

James C.

Nachricht 4 von 6
RDAOU
als Antwort auf: Anonymous

My pleasure; you're welcome

Sent from my iPhone

YOUTUBE | BIM | COMPUTATIONAL DESIGN | PARAMETRIC DESIGN | GENERATIVE DESIGN | VISUAL PROGRAMMING
If you find this reply helpful kindly hit the LIKE BUTTON and if applicable please ACCEPT AS SOLUTION


Nachricht 5 von 6
RDAOU
als Antwort auf: Anonymous

@Anonymous

 

Just a follow up in reply to your msg:

 

  1. Find the file in C:\Program Files\Autodesk\Revit 2016\en-US (Example: I am using Revit 2016 English US)
  2. Either using XML editor or copy the file to another location and rename it to Constructions.txt 
  3. Define Construction Upper section
    1. Either modify existing or add new
    2. Note the unique materialIdRef
  4. Scroll down for material definition section
    1. Most material exist (u can adjust the R and U value
    2. If you need to add new material ensure that its IDref is unique and use same naming format convention (replace the red below and leave black as is) same applies for construction format

 <Material id="mat-ADD UNIQUE NUMBER HERE">
    <Name>TYPE NAME HERE ex: 6 in metal studding</Name>
    <Description>ex: 6 in (150 mm) metal studding</Description>
   
    <Thickness unit="Meters">0.140</Thickness>
    <Conductivity unit="WPerMeterK">0.14</Conductivity>
    <Density unit="KgPerCubicM">650</Density>
    <SpecificHeat unit="JPerKgK">1200</SpecificHeat>
  </Material>

 

NOTE: Once done

  1. Rename the .txt file  back to Constructions.xml
  2. Close Revit if it is running
  3. Rename the existing/original XML to ConstructionsOLD.xml (found under C:\Program Files\Autodesk\Revit 2016\en-US again I am using Revit 2016 English US yours can be different)
  4. Copy paste the new Constructions.xml to the above directory
  5. Open Revit and try

Good Luck

Set R and U valeus for Constructions.xml.png

YOUTUBE | BIM | COMPUTATIONAL DESIGN | PARAMETRIC DESIGN | GENERATIVE DESIGN | VISUAL PROGRAMMING
If you find this reply helpful kindly hit the LIKE BUTTON and if applicable please ACCEPT AS SOLUTION


Nachricht 6 von 6
Anonymous
als Antwort auf: RDAOU

@RDAOU 

Hi, thanks for the explanation, but I have two doubts about the calculations:

1 - In your example, (25mm gypsum+ 100mm air + 25mm gypsum), In my opinion the calculations should be:

Wall R-value = Gypsum R-value + Air R-value + Gypsum R-value = 0.11030 + 0.19019 + 0.11030 = 0.32979

So, U-value is = 1/R-value = 3.03223, but in your example is 1.3289, ¿is that correct?

2 - ¿Which value uses Revit, the calulated value (2.43326) or the manually defined value (1.3289)?

Thanks for your help!

Sie finden nicht, was Sie suchen? Fragen Sie die Community oder teilen Sie Ihr Wissen mit anderen.

In Foren veröffentlichen  

Autodesk Design & Make Report