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Re: [EnergyPlus_Support] Re: Unmet Hours from Outdoor Air Units in EnergyPlus



Hello,

Calculating outdoor airflow is simple. In your model you have already specified this (or you should have), probably something like airflow per occupant, per floor area, or a mix of both. I don't know where your project is located but as far as I can tell, it's the same everywhere, there's a code that mandates it and prescribes those values (ashrae 62.1 for example).

Anyways, in your case see what the peak outdoor air requirement is. Calculate an equivalent ACH (air changes per hour, typically m3/h of required Fresh air divided by space volume), and use that for your infiltration schedule for Design Days only. Or you could use an interior equipment to do the same if cooling is the problem. Same idea...

That'll get the sizing routine to get it right.

The calc isn't complicated, but if you need more guidance let me know,

Good luck,
Julien 



Envoyé de mon iPhone

Le 19 avr. 2015 à 05:21, "ad3_prasetya@xxxxxxxxx [EnergyPlus_Support]" <EnergyPlus_Support@xxxxxxxxxxxxxxx> a écrit :

 

Hi Julien,

I am still waiting for technical specs from our mechanical team, it seems that it will took a lot of time. Therefore, for now I couldnt use other inputs than autosized things.

In my latter post, I got explanation from Jean that the unmet hours problem arises from uncorrected HVAC sizing performed by eplus as you told me also before.

Here I would like to ask you this, since increasing tolerances or throttling range doesn't produce realistic results, how about I modify the sizing:parameters to compensate the undersizing phenomenon? Because when I increased the cooling sizing factor it seems everything is lighted up. Yes, as the result, total energy consumption is increased, but at logical rate, I think. Moreover, unmet hours problem is reduced significantly due to the increased HVAC capacity from factoring the autosizes. Then, if I use the identical number in sizing:parameters on LEED's baseline case, wouldn't the results be logical enough in context of comparing between proposed and standardized scenarios mandated by LEED?

Thank you for your attention.

Regards,
A



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Posted by: Julien Marrec <julien.marrec@xxxxxxxxx>


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