Developing Framing Library to Match ASHRAE HoF Ch15 Table 4

327 views
Skip to first unread message

Greg Collins

unread,
Oct 21, 2021, 8:51:25 PM10/21/21
to Berkeley Lab WINDOW
I work as a building energy modeling consultant, and trying to get familiar with WINDOW/THERM by building out a library of window systems similar to those used in Table 4 of the ASHRAE Handbook of Fundamentals, Ch. 14 Fenestration.
Screenshot 2021-10-21 174532.png

For example, our projects often use aluminum framed fixed or curtainwall systems with low-e IGU's. I was excited at first to see "ASHRAE/LBL" options in the framing library, but they don't seem to align with the Table 4 types, and building glazed systems for Al w/break + Double Low-e Air for a Fixed type window at NFRC-100 conditions gives me a U-factor of 0.44 whereas the ASHRAE table gives 0.41 for the same. I'd also like an "Al w/o break" generic framing option.

Are there resources someone can point me to in order to either download additional ASHRAE library components, or figure out how to build my own have some default starter types similar to this ASHRAE table?  I know that there are far more complexities to modeling the framing systems in THERM than the ASHRAE table lets on, but it would be great to have a starting point.

Thanks in advance.

​Best,
Greg

Greg Collins, PE, LEED AP, BEMP | Principal

Robin Mitchell

unread,
Oct 21, 2021, 8:59:47 PM10/21/21
to Greg Collins, Berkeley Lab WINDOW
I believe that the default generic frames in THERM that are attributed to ASHRAE are quite old, and we don't have any other files that correspond to the ASHRAE number in the HOF. 

So I am not surprised that you don't get the same results as in Table 4.

It might be useful to find out the assumptions for the frames that went into generating Table 4 above. If you knew the frame U-values used for the whole window calculations, you could create those as generic frames in WINDOW and use them for the whole window calculations. 

But I don't have that information. Maybe someone else on this forum does.

Robin 



--
You can view the WINDOW forum online at: http://windows.lbl.gov/software/WINDOW/forum
---
You received this message because you are subscribed to the Google Groups "Berkeley Lab WINDOW" group.
To unsubscribe from this group and stop receiving emails from it, send an email to berkeley-lab-wi...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/berkeley-lab-window/4d332525-1fe2-430e-a94e-a1b16fa9e253n%40googlegroups.com.


--
Robin Mitchell
Building Technology and Urban Systems Division
Energy Technologies Area
Lawrence Berkeley National Laboratory

Greg Collins

unread,
Oct 21, 2021, 9:20:48 PM10/21/21
to Robin Mitchell, Berkeley Lab WINDOW
Thanks, Robin. After further reading in that chapter, I found Table 1 that provides exactly that:
image.png

If I duplicate the "al w/break" frame and replace its U-factor with the 1.80 Btu/(h-ft2-°F) I get a window system U-factor of 0.571, compared to 0.47 in Table 4. 

But then I read further, and see Figure 4 shows a framing with of 1.3 inches for this type.. If I update the 2.25" in the default assembly, I get 0.471. Jackpot! 
Making the same framing thickness change ("Projected Frame Dimension" in WINDOW) for the w/break frame, that one matches the table now as well.

I know these are rough estimates (per the first note in Table 1 above), but helpful to get started.

Best,
Greg

Greg Collins, PE, LEED AP, BEMP | Principal
image.png


Robin Mitchell

unread,
Oct 21, 2021, 11:27:05 PM10/21/21
to Greg Collins, Berkeley Lab WINDOW
Excellent that you followed through and figured this out! 

We should probably update the default frames in the WINDOW library based on the latest frames in Table 1. 

Thanks !

Paul Caicedo

unread,
Oct 28, 2022, 8:28:37 PM10/28/22
to Berkeley Lab WINDOW
Hello Greg,

I cannot find 0.41 in the second highlighted column from Table 4 - ASHRAE that you attached first. I would like to follow the process that you completed, so I can understand the process better. Would you please share some screenshots from Window?

Hi Robin,
I don't see the frames in Table 1 added to Window yet. Is this the place to look for related information in future releases? 

Thanks,
Paul

On Thursday, October 21, 2021 at 9:27:05 PM UTC-6 rdmit...@lbl.gov wrote:
Excellent that you followed through and figured this out! 

We should probably update the default frames in the WINDOW library based on the latest frames in Table 1. 

Thanks !
On Thu, Oct 21, 2021 at 6:20 PM Greg Collins <gcol...@zeroenvy.com> wrote:
Thanks, Robin. After further reading in that chapter, I found Table 1 that provides exactly that:
image.png

If I duplicate the "al w/break" frame and replace its U-factor with the 1.80 Btu/(h-ft2-°F) I get a window system U-factor of 0.571, compared to 0.47 in Table 4. 

But then I read further, and see Figure 4 shows a framing with of 1.3 inches for this type.. If I update the 2.25" in the default assembly, I get 0.471. Jackpot! 
Making the same framing thickness change ("Projected Frame Dimension" in WINDOW) for the w/break frame, that one matches the table now as well.

I know these are rough estimates (per the first note in Table 1 above), but helpful to get started.
Best,
Greg

Greg Collins, PE, LEED AP, BEMP | Principal
On Thu, Oct 21, 2021 at 5:59 PM Robin Mitchell <rdmit...@lbl.gov> wrote:
I believe that the default generic frames in THERM that are attributed to ASHRAE are quite old, and we don't have any other files that correspond to the ASHRAE number in the HOF. 

So I am not surprised that you don't get the same results as in Table 4.

It might be useful to find out the assumptions for the frames that went into generating Table 4 above. If you knew the frame U-values used for the whole window calculations, you could create those as generic frames in WINDOW and use them for the whole window calculations. 

But I don't have that information. Maybe someone else on this forum does.

Robin 



On Thu, Oct 21, 2021 at 5:51 PM Greg Collins <gcol...@zeroenvy.com> wrote:
I work as a building energy modeling consultant, and trying to get familiar with WINDOW/THERM by building out a library of window systems similar to those used in Table 4 of the ASHRAE Handbook of Fundamentals, Ch. 14 Fenestration.
Screenshot 2021-10-21 174532.png

For example, our projects often use aluminum framed fixed or curtainwall systems with low-e IGU's. I was excited at first to see "ASHRAE/LBL" options in the framing library, but they don't seem to align with the Table 4 types, and building glazed systems for Al w/break + Double Low-e Air for a Fixed type window at NFRC-100 conditions gives me a U-factor of 0.44 whereas the ASHRAE table gives 0.41 for the same. I'd also like an "Al w/o break" generic framing option.

Are there resources someone can point me to in order to either download additional ASHRAE library components, or figure out how to build my own have some default starter types similar to this ASHRAE table?  I know that there are far more complexities to modeling the framing systems in THERM than the ASHRAE table lets on, but it would be great to have a starting point.

Thanks in advance.

Best,
Greg

Greg Collins, PE, LEED AP, BEMP | Principal

--
You can view the WINDOW forum online at: http://windows.lbl.gov/software/WINDOW/forum
---
You received this message because you are subscribed to the Google Groups "Berkeley Lab WINDOW" group.
To unsubscribe from this group and stop receiving emails from it, send an email to berkeley-lab-window+unsub...@googlegroups.com.


--
Robin Mitchell
Building Technology and Urban Systems Division
Energy Technologies Area
Lawrence Berkeley National Laboratory

Reply all
Reply to author
Forward
0 new messages