Issue834: multizone residential dimensions

[Jaap-Neven]

This PR is for issue #834

1. Updated model parameters in Modelica model and layout figure in the documentation.

2. Added material properties for the internal wall, which were not declared in the documentation.

Feedback requested:

• Types of materials of internal wall were nowhere declared so I currently named them 'Internal wall outside material' and 'Internal wall inside material'. Should be changed still!
• For the internal wall, I calculated the U-value as 1/ ((d1 / lambda1) + (d2 / lambda2) + ...). This is slightly off if I check for already declared materials (like externall wall). Is there a radiative component included here?

[dhblum]

Thanks for the PR @Jaap-Neven and noticing the issues to fix. A quick question regarding your statement: "For the internal wall, I calculated the U-value as 1/ ((d1 / lambda1) + (d2 / lambda2) + ...). This is slightly off if I check for already declared materials (like externall wall). Is there a radiative component included here?"

What value did you calculate and why do you think it is off? I think the internal wall materials should be different from the external wall.

[Jaap-Neven]

Hi @dhblum, thanks for the question! I'll attempt to clarify below.

Take for example the external wall, which was already declared before this PR. In the model, I see the following structure:

And if I'm correct, I can calculate a thermal resistance by taking the resistance of each wall layer in series: R_tot = R_1 + R_2 = x1 / k1 + x2 / k2. And then U = 1/ R_tot, correct? If I apply this to the external wall declared here, I obtain R_tot = 0,2/0,2 + 0,08 / 0,032 = 3,5 -> U = 1 / 3,5 = 0,2857 [ W / m^2.K]. This deviates slightly from the declared value in the documentation which is 0,272 [ W / m^2.K]

And this is the case for all materials. Therefore, I was wondering whether there's a problem with my calculation for the newly added internal wall, or if the U-values in the documentation of the already declared materials are not up to date.

Hope this clarifies it and feel free to let me know if I should adapt something else!

[EttoreZ]

Hi @dhblum, thanks for the question! I'll attempt to clarify below.

Take for example the external wall, which was already declared before this PR. In the model, I see the following structure:

And if I'm correct, I can calculate a thermal resistance by taking the resistance of each wall layer in series: R_tot = R_1 + R_2 = x1 / k1 + x2 / k2. And then U = 1/ R_tot, correct? If I apply this to the external wall declared here, I obtain R_tot = 0,2/0,2 + 0,08 / 0,032 = 3,5 -> U = 1 / 3,5 = 0,2857 [ W / m^2.K]. This deviates slightly from the declared value in the documentation which is 0,272 [ W / m^2.K]

And this is the case for all materials. Therefore, I was wondering whether there's a problem with my calculation for the newly added internal wall, or if the U-values in the documentation of the already declared materials are not up to date.

Hope this clarifies it and feel free to let me know if I should adapt something else!

hey @Jaap-Neven. Trying to back calculate I think they added the internal surface convective resistance (Rsi = 0.13 , h=7.69 [W/m2K]). Adding that will get you U = 0.272 [ W / m^2.K]. I would say that updating the documentation to reflect the U-value only of the wall (since internal/external convective heat transfer is handled separately) would make sense. @dhblum what do you think?

Types of materials of internal wall were nowhere declared so I currently named them 'Internal wall outside material' and 'Internal wall inside material'. Should be >changed still!

@Jaap-Neven I am not sure I understand this statement, do you mean that you made a guess for the materials?
@Jaap-Neven Thank you again for your contributions!

[Jaap-Neven]

Hi @EttoreZ,

Types of materials of internal wall were nowhere declared so I currently named them 'Internal wall outside material' and 'Internal wall inside material'. Should be >changed still!

@Jaap-Neven I am not sure I understand this statement, do you mean that you made a guess for the materials?

I mean that since the materials are not declared in the documentation, I don't know what the materials are exactly (gyproc? bricks?). The materials properties are obtained from the Modelica model, so modeling-wise everything is correct. The only issue is that there are now no tangible names for the material layers in the documentation.

Regarding the U-value of the internal wall, I'll await the response of @dhblum before adapting it

[Jaap-Neven]

Added two new comments to #834 which result from newly identified issues that fit in nicely with this PR:

1. Multizone Residential Testcase dimensions mismatch #834 (comment)

2. Multizone Residential Testcase dimensions mismatch #834 (comment)

Both proposed changes have been implemented now, feel free to provide feedback on this :)

[dhblum]

Hi @dhblum, thanks for the question! I'll attempt to clarify below.
Take for example the external wall, which was already declared before this PR. In the model, I see the following structure:
And if I'm correct, I can calculate a thermal resistance by taking the resistance of each wall layer in series: R_tot = R_1 + R_2 = x1 / k1 + x2 / k2. And then U = 1/ R_tot, correct? If I apply this to the external wall declared here, I obtain R_tot = 0,2/0,2 + 0,08 / 0,032 = 3,5 -> U = 1 / 3,5 = 0,2857 [ W / m^2.K]. This deviates slightly from the declared value in the documentation which is 0,272 [ W / m^2.K]
And this is the case for all materials. Therefore, I was wondering whether there's a problem with my calculation for the newly added internal wall, or if the U-values in the documentation of the already declared materials are not up to date.
Hope this clarifies it and feel free to let me know if I should adapt something else!

hey @Jaap-Neven. Trying to back calculate I think they added the internal surface convective resistance (Rsi = 0.13 , h=7.69 [W/m2K]). Adding that will get you U = 0.272 [ W / m^2.K]. I would say that updating the documentation to reflect the U-value only of the wall (since internal/external convective heat transfer is handled separately) would make sense. @dhblum what do you think?

Types of materials of internal wall were nowhere declared so I currently named them 'Internal wall outside material' and 'Internal wall inside material'. Should be >changed still!

@Jaap-Neven I am not sure I understand this statement, do you mean that you made a guess for the materials? @Jaap-Neven Thank you again for your contributions!

The model Buildings.ThermalZones.Detailed.MixedAir in Buildings considers convective heat transfer (interior and exterior) separately from wall construction models. For interior convection, note the parameters intConMod and hIntFixed (if fixed model is chosen) and for exterior convections note the parameters extConMod and hExtFixed (if fixed model is chosen).

Can one of you check what's chosen as the convection model(s) for each room in the test case and if fixed convection is used, what that value is? I guess consider both interior and exterior. In any case, check what's there and adjust the documentation accordingly. If the convective coefficient(s) in the model are set to a constant, and you include this in what's reported in U value for the wall in the documentation, just indicate that it does for clarity. If the chosen convective coefficient model(s) is temperature-dependent, then I'd recommend no including it in the U-value reported and just indicate this choice of temperature-dependent model for convection in the documentation.

[Jaap-Neven]

The model Buildings.ThermalZones.Detailed.MixedAir in Buildings considers convective heat transfer (interior and exterior) separately from wall construction models. For interior convection, note the parameters intConMod and hIntFixed (if fixed model is chosen) and for exterior convections note the parameters extConMod and hExtFixed (if fixed model is chosen).

Can one of you check what's chosen as the convection model(s) for each room in the test case and if fixed convection is used, what that value is? I guess consider both interior and exterior. In any case, check what's there and adjust the documentation accordingly. If the convective coefficient(s) in the model are set to a constant, and you include this in what's reported in U value for the wall in the documentation, just indicate that it does for clarity. If the chosen convective coefficient model(s) is temperature-dependent, then I'd recommend no including it in the U-value reported and just indicate this choice of temperature-dependent model for convection in the documentation.

Hi @dhblum, I checked and all zones use a constant convection parameter for both inside and outside convection (screenshot below). So I can add those terms to the U-value for the newly added internal wall and update documentation accordingly.

[dhblum]

Sounds good, thanks @Jaap-Neven.