Re: [EnergyPlus_Support] ceiling, adiabatic surface or not?

["Michael J. Witte" <mjwitte@xxxxxxxx>]

The reason the first level is warmer than the top floor is because of the 
floor, which I presume has an outside environment of ground and the ground 
temperatures are much warmer than -21C.  When you allow heat transfer between 
the levels, then more heat flows out of the first level and thus it balances 
out at a cooler temperature.  So your results look reasonable for an 
unconditioned building.

Mike


On 4 May 2004, at 23:54, teklay Weldeabzgi wrote:

> you can take ceilings as an adiabatic if you set the
> indoor tempereture of the space above and below the
> ceiling is the same. otherwise you should cnsider heat
> transfer through ceilings if the temperature of the
> storise are differrent.
> 
>  in short you can take surfaces as adiabatic if the
> surface is in one zone, else take the surface as heat
> transfer surface if it separates two different thermal
> zones.
> --- pizzaalan <pizzaalan@xxxxxxxxx> wrote:
> > Thank you very much for those who helped me before. 
> > 
> > I simulated 3 story building without adding any HVAC
> > system first. 
> > If I set all ceilings between any two stories to
> > adiabatic walls, 
> > then mean air temperature of third floor is close to
> > outside 
> > environment temperature. Say outdoor temperatue is
> > -21 C, then mean 
> > air temperature of first level is 18 C, second level
> > is -2 C, the 
> > third level is -20 C.
> > 
> > If I add the heat transfer between each story by
> > setting that each 
> > ceiling's outside surface environment object is
> > floor of its upper 
> > level, then now outdoor temperatue is still -21 C, 
> > mean air 
> > temperature of first level is 15 C, second level is
> > 9 C, the third 
> > level is 5 C.
> > 
> > Should mean air temperature of each story be very
> > close? Should I 
> > view ceilling as an adiabatic surface or not? 
> > 
> > Thanks again.
> > 
> > Alan
> > 
> > 
> > 
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========================================================
Michael J. Witte, GARD Analytics, Inc.
EnergyPlus Testing and Support      
EnergyPlus-Support@xxxxxxxx



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