Overheating when cooling with natural ventilation

[javixav]

Hello everyone !

I get trouble with my model. I am using the IESVE version 2014.1.0.0

I build an office with a 19°C heating setpoint, a natural night ventilation. This freecooling makes my results having bugs.

When I observe this variables simultaneously in VistaPro :

1)Resultant temperature
2)Macro flow ext vent gain
3)heating plant sensible loads,
4) Dry bulb temperature

I observe completely unrealistic values.

1) My dry resultant temperature is around 64°C which is impossible,
2) My macroflow ext vent gain is around -420 kW,
3) My Heating plant sensible load is around 440 kW , because I have lost 420 KW with my freecooling which is impossible...
4) My dry buld temperature which is my outside temperature is correct and around 5 °C.

My opening scenario is :

gt(tdr,22,0.5) & gt(ta,to,0.5) (windows open from 0:00 to 24:00 when Toperative inside >22°C and Temperature inside > Temperature outside).


Here you can see the image of my results

<img src="C:\Users\xavier.cattelain\Desktop\Iesve_overheating">

Respectfully

[javixav]

Sorry

here you'll see the graph

http://imageshack.com/a/img673/6725/PRXZhg.png

[Complex Potential]

This looks like your window opening is far too big and too much cold air is entering the room. As a result your heating system is hammering up to compensate because you have it set to unlimited. The dry resultant temperature is shooting up because your heating system has a radiant component to it by default (0.2 I think unless you've manually changed it).

Essentially you have a massive convective heater fighting against the wide open window trying to keep the air temperature at 19C, but it is also acting as a giant radiant panel, frying anyone nearby.

Try dropping the free area of the window openings or set a limit on the heating system or set the heating radiant fraction to zero, or possibly all three.

CP