[EnergyPlus_Support] slab results and interpolation

["Jean marais" <jeannieboef@xxxxxxxxx>]

Dear Group,
Just want to share some results.
I modelled a slab 150x90 m using the slab program. the aspect ratio (area to perimeter) was set to the maximum setting and core temps were the main outcome.

the slab has a thickness of 630 mm.
the slab program has a max of 307 mm.
(manual gridding is no longer supported in e+v7)
I investigated the outcome for june at various slab thicknesses.
The results were linear as expected and I could interpolate acurately for my 630 mm slab.

Very important: the lower temp boundry condition was set at the depth of the -4 m water level in Berlin at a temperature of 9 deg C. accross Germany the annual ground temperature converges at 9 deg C at a depth of -20 m in exposed land.
Average Monthly Room Air Temp was between 18 and 22 deg C.

The outside skin temperature (the ground temp value used in e+ simulations) for my very big area 630 mm slab was interpolated at 15.5 deg C and the convergance tolerance of the solver was set to .1 deg C. All results did converge.

Notes on Large Area to Perimeter Plates:
For thicker plates, caution should be used applying the -2 deg C rule of thumb. For plates less than 300 mm this simulation was giving results in the 17 deg C.
Plates at 200 mm 

thickness in meters, bottom of slab core temp in deg C
0.1,17.874
0.15,17.691
0.2,17.423
0.25,17.19

Linear Curve Fit R=0.9975 with interpolated result at 630 mm of 15.500 deg C

0.307,16.944





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