Thermal conductivity in IP

[lmguen]

Hello Manfred,
In the material database for North America, the thermal conductivity IP units don't seem to change in Btu/h ft2.F (by the way, it's written just ft instead of square ft), they stay in SI as the values are way too low for most materials. I didn't check all the materials but a lot of them are wrong. I made sure by comparing with your sources, either ASHRAE 1018-RP or MEWS Task 3 from IRC. Just one example, the Low Density Sprayed Polyurethane Foam. It is said to have a thermal cond. of 0.021 Btu/h ft F, which is very low, it would give us an R-value of 48!!!!

Other thing, this one it might be me but after running the calculations, when you click right on the Quick Graph, you get the window saying Zoom back, Print and Export - ASC-file and picture. Well, when you save it as a picture, it goes indeed in windows save as bmp but it actually doesn't save any picture at all, at least on my version!! It did work exporting the ASC-file though...even though I had to re-learn the charts making in Excel, which are not as nice as the quick graphs.
That's it, thanks , sincerely yours

Louis-Martin Guenette
Forensic Waterproofing Consultants.

[Manfred Kehrer]

Thank you we will check this and answer

[Manfred Kehrer]

Hello Manfred,
In the material database for North America, the thermal conductivity IP units don't seem to change in Btu/h ft2.F (by the way, it's written just ft instead of square ft),

The Thermal conductivity in SI is [W/mK] an in IP [Btu/h ft °F], so it think it is right.

they stay in SI as the values are way too low for most materials.

I made a test on the first two material of the north america database and the the values for the thermal conductivity has changed from SI to IP by the factor 1.73. as recommended in the IEEE/ASTM SI10 - 2002, so the conversion seems to be OK for me.

I contacted Achilles Karagiozis last night; he is responsible for this database. He will be back at ORNL next week and should answer you then.

Other thing, this one it might be me but after running the calculations, when you click right on the Quick Graph, you get the window saying Zoom back, Print and Export - ASC-file and picture. Well, when you save it as a picture, it goes indeed in windows save as bmp but it actually doesn't save any picture at all,

It is a small Bug which only occurs if you have some specific adjustments in the Windows Explorer. In this case you have to type the filename explicit with ".bmp" at the end and it will work.

[Todd Watson]

Because the unit provided is thermal conductivity not thermal conductance, the correct unit nomenclature should be (Btu ft)/(hr ft2 F). This has been reduced to Btu/(hr ft F). If you divide the thermal conductivity by the material thickness in feet you will get the thermal conductance of the material for the given thickness. This is the equivalent to the permeability for the material, that is, the reported value must be divided by the material thickness. Regards.

Todd Watson, P.E.