Dear Athinodoros,
I do not think that the ventilated slab object is intended to represent a hollow core slab for the purposes of conduction through the slab. Instead, it models conduction from and to the slab based on the energy transfer to and from the fluid inside the cores. (I found a description in the Engineering Reference and show it below.)
It is always possible to convert from one version of E+ to a later version using the EP-Launch File, Transition Version feature for a single version update. Also, you may use the Multiple IDF Version conversion program found at: http://energyplus.helpserve.com/Knowledgebase/List/Index/47
Ventilated Slab
Model Overview
The input object ZoneHVAC:VentilatedSlab provides a model for ventilated slab systems that
in general use outdoor air to “precool” slabs with colder nighttime air. This method of
precooling the thermal mass of a space can be very effective when nighttime temperatures
are low and the mass of the system is high enough to provide a significant amount of cooling…
James V Dirkes II, PE, BEMP, LEED AP
www.buildingperformanceteam.com
Energy Analysis, Commissioning & Training Services
1631 Acacia Drive, Grand Rapids, MI 49504 USA
616 450 8653
From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Athinodoros Tzoulis
Sent: Sunday, November 03, 2013 5:15 PM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: Re: [EnergyPlus_Support] hollow core slabs
Dear James,
I have read in the website of EnergyPlus http://apps1.eere.energy.gov/buildings/energyplus/energyplus_archives.cfm that it is possible to model hollowcore slabs since version 3 in the ZoneHVAC:VentilatedSlab:SlabGroup but I do not know exactly how to make it as a layer of a thicker slab which has a heated floor and provides no ventilation.
Do you know if this is possible?
Secondly, I saw that in EnergyPlus v8 is possiple to apply multiple tubing circuits in a slab. However, I use Designbuilder v3 which connects only to EnergyPlus v7. Is there a possibility to convert the idf files from Designbuilder from EnergyPlus version 7 to EnergyPlus version 8?
Thank you in advance
Athinodoros Tzoulis
On Sunday, November 3, 2013 8:50 PM, Jim Dirkes <jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
Dear Athinodoros,
EnergyPlus cannot model non-homogeneous layers such as the hollow core slab. That layer should be modeled with the correct mass (thickness + density) and an average conductance.
The embedded pipes are not something I have modeled, but I believe that there are several radiant floor objects that will work for you. Look into object names such as ZoneHVAC:LowTemperatureRadiant:ConstantFlow.
James V Dirkes II, PE, BEMP, LEED AP
www.buildingperformanceteam.com
Energy Analysis, Commissioning & Training Services
1631 Acacia Drive, Grand Rapids, MI 49504 USA
616 450 8653
From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Athinodoros Tzoulis
Sent: Sunday, November 03, 2013 12:18 PM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: [EnergyPlus_Support] hollow core slabs [1 Attachment]
Hi all,
I have 2 questions.
1) I would like to model a hollow core slab in a room and above it a concrete layer with embedded water pipes for concrete core activation.
Is there a possibility to do it in EnergyPlus?
I have seen a possibility to do it in but as a ventilated slab. However I don't want ventilation in the room.
2) I have modelled a room with a heated floor inside a solid concrete slab.
Is it possible to separate the system in 2 or more loops within the slab. So, having embedded tubes in the slab in the whole slab but having more than 2 water inlet and outlet nodes (as it is in reality)? (see pic)
Is there a possibility to model this system with virtual partitions?
Best regards,
Athinodoros Tzoulis
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