Ground floor thickness and Zone Volume

Carlos · Posts: 25

Hi all,

I'm doing some simulations to determine the Ground Temperatures I will use.

I did all my building with 'Combined Constructions'. It's problematic to use 'Ground Construction', since it requires 'Separate Constructions', and, it requires practically to 're-build' my building.

So, I decided to put the ground layer in the Floor construction (under the slab). It's equivalent in terms of simulation, but problem comes using 4m of earth.

(Here and on I will write in UpperCase to distinguish from Error Messages).

FIRST, THE PROBLEM WHEN TRYED TO SIMULATE WAS:

Prototipo 2 Base - Total zone volume - floor void volume - ceiling void volume + link volume must be > 0 BLOQUE DENTRO SUR - Zona Dentro Sur

IT SEEMS THAT THE ZONE VOLUME IS BEING CALCULATED SUBSTRACTING THE GROUND FLOOR CONSTRUCTION, RIGTH? MY FIRST CONFUSSION IS THAT ALL THIS TIME I HAVE BEEN THINKING THAT ZONE VOLUME AND HEIGHT ARE 'INNER'. NOW I DON'T KNOW. WHEN I INTRODUCED THE BLOCK HEIGHT, I DID WITH THE HEIGHT FROM UPPER SIDE OF FLOOR TO LOWER SIDE OF CEILING, IS IT RIGHT OR NOT????

I WENT TO THE HELP AND SAYS IT'S POSSIBLE TO SELECT IF THE GROUND FLOOR CONSTRUCTION IS OR NOT GOING TO BE SUBSTRACTED FROM THE ZONE VOLUME (IN MODEL OPTIONS), BUT... THAT OPTION IS NOT THERE (SEEMS IT'S ONLY FOR V 1.5, NOT FOR V 1.4). THE ONLY OPTION IS "INCLUDE CONSTRUCTION IN ZONE VOLUME". THE ABOVE ERROR WAS SHOWED WHEN IT WAS UNCHECKED. SO, CHECKING IT AVOIDS THE VOLUME (AND HEIGHT) TO BE SUSBTRACTED FROM ZONE VOLUME AND HEIGHT VOLUME???, AND, WHAT ABOUT THE ROOF? IT IS OR NOT BEING SUBSTRACTED????

HOW IS DB V 1.4 CONSIDERING HEIGHT AND VOLUME? WHERE CAN I CHECK HOW THE PROGRAM IS CONSIDERING BOTH INTERNALLY (NOT WHAT I INTRODUCED, WHAT IT IS REALLY CONSIDERING) AND SO SEE "THE ZONE VOLUME IS..."

THEN, I CHECKED THE OPTION, BUT NOW THE ERROR IS:

Program Version,EnergyPlusDLL 2.1.0.023, 20/05/2008 06:16 p.m.,IDD_Version 2.1.0.023
** Severe ** Out of range value Numeric Field#1 (Thickness), value=4.00000, range={>0 and <=3.0}, in MATERIAL:REGULAR=13_1_101
** Severe ** Out of "range" values found in input
** Severe ** Out of "range" values and/or blank required fields found in input
** Fatal ** Errors occurred on processing IDF file. Preceding condition(s) cause termination.
...Summary of Errors that led to program termination:
..... Reference severe error count=3
..... Last severe error=Out of "range" values and/or blank required fields found in input
************* Warning: Node connection errors not checked - most system input has not been read (see previous warning).
************* Fatal error -- final processing. Program exited before simulations began. See previous error messages.
************* EnergyPlus Terminated--Fatal Error Detected. 0 Warning; 3 Severe Errors; Elapsed Time=00hr 00min 1.55sec

IT SEEMS THEN THAT THE VOLUME IS NOT THE PROBLEM ANYMORE, BUT THE LAYER WIDTH. MY CONSTRUCTION IS 0.1M OF CONCRET AND 4M OF EARTH. THE ERROR IS ABOUT A MATERIAL OF 4M THICK, NOT ABOUT A 4.1M THICK. SO A TRIED WITH A 3-LAYER CONSTRUCTION, 0.1M OF CONCRETE, 2M OF EARTH... AND OTHER 2M OF EARTH. THE ERROR IS NOW:

Program Version,EnergyPlusDLL 2.1.0.023, 20/05/2008 06:30 p.m.,IDD_Version 2.1.0.023
** Warning ** For a zone sizing run, there must be at least 1 Zone Sizing object input. Zone Sizing Run Control option ignored.
** Warning ** GetGroundTemps: Some values for "GroundTemperatures" fall outside the range of 15-25C.
** ~~~ ** These values may be inappropriate. Please consult the Input Output Reference for more details.
** Warning ** Weather file location will be used rather than entered Location object.
** ~~~ ** ..Location object=PROTOTIPO 2
** ~~~ ** ..Weather File Location=EL CENTRO CA USA TMY--00015 WMO#=747185
** Severe ** CTF calculation convergence problem for 13
** ~~~ ** The potential causes of this problem are related to the input for the construction
** ~~~ ** listed in the severe error above. The CTF calculate routine is unable to come up
** ~~~ ** with a series of CTF terms that have a reasonable time step and this indicates an
** ~~~ ** error. Check the definition of this construction and the materials that make up
** ~~~ ** the construction. Very thin, highly conductive materials may cause problems.
** ~~~ ** This may be avoided by ignoring the presence of those materials since they probably
** ~~~ ** do not effect the heat transfer characteristics of the construction. Highly
** ~~~ ** conductive or highly resistive layers that are alternated with high mass layers
** ~~~ ** may also result in problems. After confirming that the input is correct and
** ~~~ ** realistic, the user should contact the EnergyPlus support team.
** Fatal ** Program terminated for reasons listed (InitConductionTransferFunctions)
...Summary of Errors that led to program termination:
..... Reference severe error count=1
..... Last severe error=CTF calculation convergence problem for 13
************* Fatal error -- final processing. More error messages may appear.
************* Testing Individual Branch Integrity
************* All Branches passed integrity testing
************* Testing Individual Supply Air Path Integrity
************* All Supply Air Paths passed integrity testing
************* Testing Individual Return Air Path Integrity
************* All Return Air Paths passed integrity testing
************* No node connection errors were found.
************* EnergyPlus Terminated--Fatal Error Detected. 3 Warning; 1 Severe Errors; Elapsed Time=00hr 00min 3.00sec

PLEASE EXPLAIN ME A LITTLE ABOUT RESTRICTIONS FOR THICKNESS AND FOR CONDUCTIVITY RESTRICTIONS.

Regards,

Carlos

Laurent_Support · Posts: 292 Location: Vincennes

Hello Carlos,

Don't sink in problems!
First of all do you think to use the ground construction layer available at site level in the Site tab?

It allows you to add a ground thickness to every surface set adjacent to ground without changing anything to you wall, slab constructions.

This option is not normally indented to model 4m ground but if you really want to, it will be simpler.

To avoid error messages, you must limit your thickness to 3m (as you read!).

The last problem you met (Last severe error=CTF calculation convergence problem for 13 ) means EnergyPlus don't succeed in calculate material temperature. Probably because it is too thick and dense.
You could try to lower calculation time step and rise convergence limits but it is not certain it will pass.

Good luck,
Laurent

Carlos · Posts: 25

Hi Laurent,

Sorry, I will keep sinking in problems Smile

that's a way to become expert.

"First of all do you think to use the ground construction layer available at site level in the Site tab?"

At first I thought it would be difficult to work with Separate Constructios when I had already made up my own constructions, but I'm looking at it again and seems it's not much problem (just ignoring 'Floor fitted above slab', 'suspended ceiling' and 'external floor (below slab)'. Just a few simpler questions:

1) In Combined Constructions, the options for floor have
External Floor, Internal Floor.
In Separate Constructions, the options for floor have
External Floor (below slab), Internal Floor Slab.

In the second option, the Internal Floor Slab is also the one that is above External Floor?

2) In Combined Construction, Cheking 'Include constructions in zone volume -> Floor construction' means DB won't substract the floor volume from zone volume? (v 1.4)

3) In Combined Costruction, there's no such an option for roofs. Is DB substracting or not the roof volume from the zone volume? (v 1.4)

4) In Separate Construction, the option changes to 'Include constructions in zone volume -> Floor voids' and '-> ceiling voids'. The same as before, cheking the options means these voids are not substracted from zone volume? (v 1.4)

5) I don't understand why only checks for the voids and not for the whole construction.

6) In Separate Construction, the option 'Include constructions in zone volume -> Floor construction' does not exist. So, in this case, DB is substracting or not the floor (ground slab) volume from zone volume?

7) Where can I ask the program for the calculated Zone volume?

Thanks,

Carlos

Laurent_Support · Posts: 292 Location: Vincennes

Hello Carlos,

Here you will find pictures that explain better than any long answer what is modeled with Separated or Combined option:
http://www.designbuilder.co.uk/helpv1/Content/Constructions.htm

Volume and surface computed are also shown by lines around the room.
Please have a look to this topic.

rahmiandarini · Posts: 43

Hi Carlos,

For your question concerning zone volume, maybe you can try to check the zone volume using Energy Plus.
Hopefully it helps.

Good luck,
Rahmi

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