Re: [EnergyPlus_Support] Cycling fans when spaces are unoccupied

[Richard Raustad <RRaustad@xxxxxxxxxxxx>]

Yes, that's correct. Response from James is also a good one for VAV.

There is an availability schedule for coils and fans.
For cycling systems, the fan and coils are scheduled on all the time and the system runs to meet the load. The fan operating mode schedule tells the fan to run continuously during the day or cycle on and off at night.
For VAV systems, the fan is scheduled on only during occupied hours, the coils are scheduled on all the time. The night cycle manager will override the fan schedule and turn the fan on at night if necessary (and since the coils are scheduled on, you get cooling or heating).

On 8/16/2012 10:51 AM, Carolina Galeazzi wrote:

Hi Richard,

Thank you for your answer.

So, the correct values for cycling fans in the fan operation mode schedule is:

 

0 (denotes cycling fan operation), used in unoccupied hours;

1 or other value other than 0 (denote continuos fan operation), specified for occupied hours.

 

Is this correct?

Carol

De: Richard Raustad <RRaustad@xxxxxxxxxxxx>
Para: EnergyPlus_Support@xxxxxxxxxxxxxxx
Enviadas: Quinta-feira, 16 de Agosto de 2012 11:26
Assunto: Re: [EnergyPlus_Support] Cycling fans when spaces are unoccupied

 

Just because you don't need to be bring OA in at night doesn't mean that you don't need to condition the zones, which means the supply fan must turn on.
During the day, the fan runs continuously to ensure the proper amount of OA, during the night, if there is a load, the fan turns on and off with the coils.

There is usually a fan operating mode schedule used with HVAC equipment that can cycle, or you can use a night ventilation manager to cycle the fan on for VAV systems.
OA control is independent of fan operation (i.e., you can have OA or not if the fan is running).

On 8/16/2012 10:12 AM, Carolina Galeazzi wrote:

Hi All,

 

To build an ASHRAE baseline model, it's said that 'supply and return fans should be cycled to meet heating and cooling loads during unoccupied hours'. I understand that fans should run for mechanical ventilation, but with zero outside airflow rate. How can I cycle the variable volume fan of the AHUs in Eplus, with zero outside airflow rate?

Thank you for your help!!

Carol

 

  

-- 
Richard A. Raustad
Senior Research Engineer
Florida Solar Energy Center
University of Central Florida
1679 Clearlake Road
Cocoa, FL  32922-5703
Phone:   (321) 638-1454
Fax:     (321) 638-1439 or 1010
Visit our web site at: http://www.fsec.ucf.edu/

UCF - From Promise to Prominence: Celebrating 40 Years

-- 
Richard A. Raustad
Senior Research Engineer
Florida Solar Energy Center
University of Central Florida
1679 Clearlake Road
Cocoa, FL  32922-5703
Phone:   (321) 638-1454
Fax:     (321) 638-1439 or 1010
Visit our web site at: http://www.fsec.ucf.edu

UCF - From Promise to Prominence: Celebrating 40 Years

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