Emissivity Reporting.

[Philip Davies]

Hi Justin, 

I'm running a simulation in Therm 7.8.74.0 of a double hung window made from U-PVC, with a Galvanized reinforcement box section in one of the U-PVC hollow chambers.

I am using the CEN method (EN ISO 10077-2) and have used simplified air cavities set to ("CEN Cavity" 0.9/0.9 for non-metallic surfaces),  (0.3/0.3 internal hollow of the Galvanised hollow box section) & (0.3/0.9 for the cavities between the U-PVC and Galvanised box section).  

Nothing unusual about this, I do this all the time and is a requirement for 10077-2 and the BFRC. 

Simulation runs just fine, results and report are generated. However, I note in the Report, under the cavities calculations for 0.3/0.3 & 0.3/0.9, sides 1 & 2 are both showing 0.9. (See attached Report PDF)

Also, Double Clicking on the actual 0.3/0.3 Cavity in the window model show sides 1 & 2 as 0.9/0.9 in the pop-up Properties Dialogue menu, but when you click on the Library button it shows sides 1 & 2 as 0.3/0.3, as the should be!?!? (See attached Screen Capture PDF)

I was using Therm 5 before Therm 7.8 and, in Therm 5, the Report shows the cavity sides as set, so does the Properties Dialogue menu.  

I have also attached the one Therm 7.8 file that the two attached PDF's relate to.  There are five Therm files/cross-sections to this project, the other four files are showing the same issue with the cavity emissivity's.

I've run some tests in Therm 7.8 using a simple hollow Galvanised box, (made up of two channels as Therm doesn't like closed hollows), with the one CEN Cavity 0.9/0.9, and all seemed to be simulating normally. Reports and Properties were saying sides 1 & 2 as they were set. When I change the cavity to 0.3/0/3 and re-run simulation, report shows emissivity's correctly, likewise for the 0.3/0.9 model.  But when creating two hollow boxes touching side by side in the same file with one cavity set to 0.9/0.9 and the other set to 0.3/0.3, the report listed both cavity results as side 1 as 0.3 & side 2. as 0.9. (The two cavities were completely separated by solid materials). Then, when I deleted one of the boxes and its cavity then re-simulated the one remaining box with just one cavity set to 0.9/0.9, the Therm Report showed the results with side 1. at 0.3 and side 2. as 0.9, even though there were no cavities set with emissivity's set to 0.3! Strange!

Can you help please.

Thanks,

Phil.

    

[archi...@gmail.com]

Hi Phil

I looked at your model, which is really perfectly modelled.

I tried to substitute the CEN 0.3/0.3 and 0.3/0.9 cavities which have inconsistent behaviour with unventilated cavities 0.3/0.3 and 0.3/0.9 with "Cavity Model" set to "ISO 15099" and it seems to be working. I don't know if this is correct according to current EN ISO standards. I did not change your CEN 0.9/0.9 cavities.

I then set "View/Gravity Arrow" "Into screen", because it is considered in cavities calculation and eventually in "File/Properties" I set "Cross Section Type" to "Vertical Meeting Rail", even if this is only a detail's description which does not interfere with calculation (I suppose).

Please find attached the changed Therm file, a screen shot of the cavities settings and the calculation report.

Ciao

Fabrizio

[Phil Davies]

Hi Ciao,

 

Thank you so much for taking the time to look over my sim issue and your suggestions. Very much appreciated.

 

Unfortunately, we can not use the 15099 standard in the UK for BFRC projects, it has to be 10077-2. Personally, I prefer 15099 method, its simpler and quicker than 10077-2, only one simulation per cross-section required, unlike 10077-2 which requires two simulations per cross-section, at least double the work, but rules are rules and we have to use 10077-2.

 

I see in the Therm Report you attached that the 0.3/0.3 & 0.3/0.9 cavity results have varying emissivity, this would also be a no, no for 10077-2, the emissivity’s must remain as set, i.e. 0.3 or 0.9, or a mix for sides 1 & 2.

 

Therm 5 reports the emissivity’s as set, so there may be a glitch in Therm 7.8, because the tests I did using a simple box with one and two cavities, were still showing the emissivity results incorrectly. I think the actual simulation results are correct, but something is amiss with the way the emissivity results are being displayed after simulation has been carried out.

 

Thanks again,

 

 

Phil.

 

Philip Davies

 

41 Gordon Road

Blackwood

Caerphilly

NP12 1DW

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[Phil Davies]

Hi Ciao,

 

Attached is a report from Therm 5.x. Using similar materials and same cavity models as the ones in the Therm 7.8 file from yesterday.

 

As you will see, sides 1 & 2 emissivity results are consistent with the type of cavity model selected, they do not vary like the results in the report you sent using the 15099 method.

 

The properties also reflect the type of cavity model selected.  e.g. if I double click on a cavity set to 0.3/0.9, the properties say that side 1 is 0.3e and side 2 is 0.9e.

 

Thanks,

 

 

Phil.

 

Philip Davies

 

41 Gordon Road

Blackwood

Caerphilly

NP12 1DW

 

From: lbnl-...@googlegroups.com <lbnl-...@googlegroups.com> On Behalf Of archi...@gmail.com
Sent: 19 December 2024 10:46
To: THERM <lbnl-...@googlegroups.com>
Subject: [LBNL-THERM] Re: Emissivity Reporting.

 

Hi Phil

--

[Phil Davies]

Hi Ciao,

 

I also note when setting the gravity arrow into screen the heat flow direction in the Therm 7.8 Reports to be in all sorts of direction, most are saying Left to Right! How is this possible when the boundaries are set: internal on the right and external on the left, and heat flow travels from hot to cold?

 

When setting the gravity arrow to down, as I normally do, report says Horizontal, but a few are saying Up or Down!

 

I was under the impression that when in simplified mode, the heat flow direction is dictated by the internal and external positions.  

 

I am very confused.

 

 

Phil.

 

Philip Davies

 

41 Gordon Road

Blackwood

Caerphilly

NP12 1DW

 

From: lbnl-...@googlegroups.com <lbnl-...@googlegroups.com> On Behalf Of archi...@gmail.com
Sent: 19 December 2024 10:46
To: THERM <lbnl-...@googlegroups.com>
Subject: [LBNL-THERM] Re: Emissivity Reporting.

 

Hi Phil

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[Robin Mitchell]

FYI, LBNL shuts down from Dec 23 through Jan 1, and so the issues raised in this thread won't be addressed until probably the week of Jan 6. 

I haven't been able to completely follow the complete set of issues being brought up in this thread. 

If you think that there are bugs in THERM 7.8.74 related to the issues you are raising here, it would be good to try to summarize those for our development team, using this file as an example, so that we can investigate the specific situations. 

Putting that summary, in this thread, of the problems you are seeing would help us investigate them in the new year. 

Thank you and have a good holiday. 

Robin

To view this discussion visit https://groups.google.com/d/msgid/LBNL-THERM/DB4P250MB1006D9E85077FBF75441B054C1062%40DB4P250MB1006.EURP250.PROD.OUTLOOK.COM.

--

Robin Mitchell

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

[Phil Davies]

Hi Robin,

 

Thanks for the heads up about the shut down for the holidays, I will try to summarise the issues I’m having with the way Therm 7.8.74 is reporting the emissivity’s results and heat flow direction.

 

I will try to get the summary posted tomorrow, but completely understand this will be looked at in the New Year.

 

Thanks for all the support thus far and hope you have a good holiday too.

 

Thanks again,

 

 

Phil.

 

Philip Davies

 

41 Gordon Road

Blackwood

Caerphilly

NP12 1DW

 

[Robin Mitchell]

Phil

That would be great !

I am so appreciative of the support that all of you give each other on this forum. 

You all, as experienced users, know a LOT more about using THERM than we do as developers, and seeing the issues you are experiencing is very valuable to us. And the fact that all of you are so generous with your time to help each other is amazing and much appreciated by our software development team !!

Thank you so much !!

Robin

[archi...@gmail.com]

Hi Phil

Yes, you're definitely right. These non ventilated air cavities have a strange behaviour even on declaring flux direction.
Talking about "gravity arrow", I think that I didn't understand your detail is actually a vertical section of a sash window, isn't it? In this case my "gravity arrow" "into screen" setting is wrong.
As written by Robin let's see if it is really a bug and what developers will answer.

Good holiday and thanks to all LBNL staff for developing Therm!

Ciao

Fabrizio

[Phil Davies]

Hi Ciao,

 

The none-ventilated cavities, do seem a bit odd, I’m glad its not just me that thinks so, as I was leaning more towards I’d been doing something wrong!

 

The window in my first example is a double hung/vertical sliding sash and the original profile is the meeting style (aka interlocker), which would be in fitted in the horizontal position so gravity would be down in this case. However, when simulating to 10077-2 and the rules set out by the BFRC, we tend to keep the Gravity Arrow as Down in all windows and doors mounted in vertical walls. Think this varies with roof/sky lights, but I’ve not been involved much with this sort of positioning.

 

I’ve just sent the information that Robin suggested, so hopefully that will help this issue with cavity modelling.

 

You have a good one too,

To view this discussion visit https://groups.google.com/d/msgid/LBNL-THERM/df033409-9136-4e70-95a8-d57e69f01d67n%40googlegroups.com.

[Phil Davies]

Sorry everyone,

 

Just realised, I originally click reply to Robin only by mistake.

 

See attached and below.

 

Happy Holidays,

 

 

Phil.

 

Philip Davies

 

41 Gordon Road

Blackwood

Caerphilly

NP12 1DW

 

From: Phil Davies
Sent: 20 December 2024 16:59
To: Robin Mitchell <rdmit...@lbl.gov>
Subject: RE: [LBNL-THERM] Re: Emissivity Reporting.

 

Hi Robin,

 

Not sure if you can class the following as a summary, as I’ve shown the possible issues with Therm 7.8.74 as comparison with Therm 5.2.14, which I believe is reporting the emissivity’s ETC. correctly.

 

Attached are results and reports for simulations conducted in Therm 5.2x and 7.8x. The exact same window profile cross-section has been used in both versions of Therm, this includes all materialS, solid and frame cavities. Like wise for the Boundary Conditions and, to the best of my knowledge, the same Therm settings too.   

 

Therm 5.2x

 

            Therm file (Therm 5_2 U1 OFS Head Top Rail F1-F2.THM)

 

            Therm Report (Therm 5_2 U1 OFS Head Top Rail F1-F2.pdf)

 

Therm 7.8x

 

            Therm file (Therm 7_8 U1 OFS Head Top Rail F1-F2.THM)

 

            Therm Report (Therm 7_8 U1 OFS Head Top Rail F1-F2.pdf)

 

ALso attached is a two-page pdf document, (Therm 5 v Therm 7 Polygon Properties & Material Lib.pdf), depicting the differences in how the two Therm versions are reporting/displaying the various Emissivity’s for Frame Cavities. I think this is self-explanatory, but please contact me if further explanation is required.

 

In the Therm 5.2 Report (attached pdf) you will see all three Frame Cavity types used in this simulation, (0.9/0.9,  0.3/0.3 & 0.3.0.9) under each of the material headings, the results for each cavity shows the relative emissivity for Side 1 and Side 2 as per the heading. Also, as I’ve used the Gravity Arrow as “Down”, ALL heat-flow directions are showing Horizontal. I believe this is the correct way to display the results in the Therm Reports. Final U-Factor = 1.0165 W/m²-k

 

In the Therm 7.8 Report (attached pdf), unlike Frame Cavity “CEN Cavity 0.3/0.3” that matches the headings to the results for Side 1. & Side 2., the other two Frame Cavity types, 0.3/0.9 & 0.9/0.9, do not match, the results for Sides 1 & 2 both say 0.3/0.3. Gravity Arrow is also set to “Down”, but I note that the heat-flow directions are not all horizontal, some are Up and some are Down! Final U-Factor = 0.8683 W/m²-k. Which is a significant difference to Therm 5.2!

 

I have been using Therm since ~2001, Therm 5.2.1.4 since it was issued to now. As a registered simulator with the BFRC (similar to the USA NFRC), we can only use software that has been approved by the BFRC Technical Comity. There are approximately 50 registered simulators, some use different software, like WIN ISO, Bisco, Flixo etc. Every year, all registered simulators must take an exam set out by the BRFC to ensure we are all singing from the same hymn sheet! To Date, all our simulation results have been comparable across all the different simulation software types. I’m not quite up to speed with all the new features of Therm 7.8.74 yet, most of it seems to me the same logic as Therm 5.x, but I’m very confused why the emissivity’s and heat flows are being reported so differently to Therm 5.x. I wasn’t expecting such a marked difference between the two U-factor results either.

 

I hope the above and attached is understandable, if you have any questions at all, please let me know anytime.

 

Thanks again for all the support and I hope you all enjoy the Holidays.

 

Kindest regards,   

[Phil Davies]

Hi Robin,

 

Hope you are ok.

 

I can see from the plethora of emails on the LBNL group, that you are extremely busy, but I was just wondering if you had an update on the below Emissivity issues.

 

I did send a “summary” of the issues and some file examples, but I’m not sure if they were any help for your software team.

 

Thanks,

[Phil Davies]

Hi Robin,

 

Hope you are keeping well.

 

Sorry to nag, but do you have any further information on the below issues with emissivity’s please.

 

Thanks,

 

 

Phil.

 

Philip Davies