My most recent analysis was an unconditioned building with lots of solar gain. I tried iterating slab with calculated space temperatures, but it would not
match my measured conditions during the summer. I could only match measured summer conditions by manually inputting under slab temperature values. I think a hint about the issue is that slab works with the space temperature but does not concern itself with
solar gain. Slab probably works fine for a dark basement.
Ned Lyon, P.E. (MA, WV)
Staff Consultant
SIMPSON GUMPERTZ & HEGER
781.907.9000 main
781.907.9350 direct
781.907.9009 fax
www.sgh.com
From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx]
On Behalf Of FrancescoP
Sent: Tuesday, June 04, 2013 12:49 PM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: [EnergyPlus_Support] Re: Ground heat transfer from an uninsulated floor of an unconditioned sunspace
I add that I'm considering F. Droulia et al (2009) "Ground temperature estimations using simplified analytical and semi-empirical approaches" and other methods in order to estimate the ground temperature to use in the object
Site:GroundTemperature:BuildingSurface
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "FrancescoP" <fpasserini.tn@...> wrote:
>
> I'm modelling an unconditioned sunspace. The floor is not insulated: it is made by 10 cm concrete and then there is the ground. The adjacent building is unconditioned too. It is situated in an Alpine region in Northern Italy. I have to validate the model
through a comparison between the output data of the simulation and the monitored data.
> I wondering whether using the "slab pre-processor" would be the best solution. In fact, in the model of the "slab pre-processor" the internal temperature has a sinusoidal hourly variation while in my case the internal temperature changes quickly and irregularly
and because of the solar radiation the temperature inside the sunspace is often very different than the outdoor air.
> I think that an alternative solution could be modelling the floor considering not only the concrete, but also a depth of the ground. I have calculated the thermal trasmittance through the ground between sunspace and external environment with a FEM software,
then I have createe a construction with 10cm concrete + ground (50cm ?) + "virtual layer" in order to match the calculated U-value. On the bottom side of the construction, in the field "Outside Boundary Condition" of the object BuildingSurface:Detailed relative
to the floor, I'm trying using both using "Outside" and using "Ground" but I see only a small difference, probably because of the great thickness of the ground layer.
> Any suggestion, please? Should I use the "slab pre-processor"?
> Moreover, I think the problems that I have with the validation concern also the distribution of solar radiation, but for this message I think I have written enough :-)
> Regards
> Francesco Passerini
>
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