ÂGerman,If you set the ventilation rate in the ZoneHVAC:FanCoil Object it will account for the ventilation in the zone level sizing (only in expanded file)You can then use differing OA schedules to say that the zone ventilation is available only during the sizing period, and the system level ventilation is available during the run periodI think you must be speaking of when using the HVAC Templates, as when the templates expand, if theres a DOAS, Energyplus writes the OA in the FCU to 0 per this note and sets the ventilation in the DOAS! Setting fan coil outdoor air to zero, because zone is served by dedicated outdoor air system (DOAS)-JasonOn Thu, Jul 3, 2014 at 10:06 PM, 'jeannieboef@xxxxxxxxx' jeannieboef@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:
ÂHi Karen, as soon as you posted this, I went to test it, because it messes up my current understanding of the autosizing in e+. For Germà n's case, it does not work and fits my current mental model. For HJ's case, it would work as long as the zone setpoint is able to be corrected by the system's air supply. So if he has a zone heating setpoint of 20 and is trying to heat with 13 C system supply air, it will not size the equipment properly and the issue is the same as Germà n's. ÂMit freundlichen GrüÃ?en- Sent from my iPhone (excuse the brevity)i. A.Jean Maraisb.i.g. bechtoldTel.  +49 30 6706662-23
On 03.07.2014, at 23:53, "Karen Walkerman kwalkerman@xxxxxxxxx [EnergyPlus_Support]" <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:
ÂI think that you might not be setting the design heating and cooling supply air temperatures correctly in the Sizing:System object. If you have an air handler providing unconditional ventilation air to zones, set the design heating temperature equal to the outdoor temperature of your heating design day at the system level. Same with cooling. Then your ZoneHVAC equipment should size correctly.
Karen
On Jul 3, 2014 12:30 PM, "HJ wanghaojie630@xxxxxxxxx [EnergyPlus_Support]" <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:
ÂThanks. I misspoke, actually s1 provide 13 air temperature all time. So in summer it provide some cooling, and winter it preheat air to 13 C. In this case, will s2 be oversized for summer and undersized for winter?
HJ
ÂIn your case, s2 will only be sized for zone loads without accounting for s1 ventilation load. But, as you say, your s1 system provides neutral air temperature, that is, no load. In that case you do not have the problem I mentioned.
Regards.
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Posted by: Jean Marais <jeannieboef@xxxxxxxxx>
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