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[EnergyPlus_Support] Re: Indoor air temperature LOWER than ambient temperature

Hi Ned,

Thank you for your reply. While you are probably right, ground floor temperature cannot be the only reason to account for indoor temperature going lower than ambient. In my simulation, the night time temperature is about 11-16C, which is much lower than the ground temperature of 18C.

Ryan

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Edward G. Lyon" <eglyon@...> wrote:
>
> This could happen in warm weather if you have a relatively large slab on grade floor. EPlus will always loose room heat to the floor, so by early morning with no solar gain and radiant heat loss to the sky, your interior temperature could drop a little below exterior ambient if you don't have a lot of infiltration or fan ventilation.  If you look at the ground temperature calculations for floors, they are always lower than the ambient room.   The calculation for floor heat loss is based on smaller buildings and doesn't seem to properly deal with large slab on grade floors which could function as heat storage mechanisms under certain conditions.
> 
> Ned Lyon, P.E. (MA)
> 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 academicryan
> Sent: Friday, August 17, 2012 3:48 AM
> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> Subject: [EnergyPlus_Support] Indoor air temperature LOWER than ambient temperature
> 
> 
> 
> Hi
> 
> I've been doing E+ simulation for over half a year now and feel like I have a good grasp of it. But one thing I can't figure out is why I sometimes get results of indoor temperature being lower than ambient temperature. This often occurs during the early morning, 3am-9am. In reality this is impossible so I'm very confused by this result.
> 
> Can someone please explain to me why E+ produces this result?
> 
> If requested, I can attach additional information such as .idf or excel graph.
> 
> Many thanks,
> 
> Ryan
>




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