Re: [EnergyPlus_Support] Zone Ventilation Fan Electric Consumption

On Mon, Jul 16, 2012 at 2:50 PM, Vinay Devanathan <vinay.devanathan@xxxxxxxxx> wrote:

When you use the ZoneVentilation:DesignAirFlow object for ventilation, the electric consumption of these fans are grouped in Fans end use, so if you look at the table - End Uses by subcategory, there will be something called SimpleVentilation. This is the ZoneVentilation object.

On Mon, Jul 16, 2012 at 2:47 PM, CleanTech Analytics <jeremiah@xxxxxxxxxxxxxxxxxxxxxx> wrote:

I am under the impression that the design ventilation object is used for sizing only, and that you will need to use the previously mentioned recommendation to actually effect consumption.

Jeremiah D. Crossett

CleanTech Analytics
503-688-8951

www.cleantechanalytics.com

This document may contain valuable information proprietary to CleanTech Analytics which is private and confidential. It may not be shared, copied, stored or transmitted in any form without the prior written consent of CleanTech Analytics

On Mon, Jul 16, 2012 at 10:45 AM, Niraj Poudel <nirajpdl@xxxxxxxxx> wrote:

Jeremiah,

Thank you so much for looking into this. I just went over the I/O reference (Page 391) about the Zone:Ventilation:DesignFlowRate and under the Field: Ventilation Type this is what it says:

Field: Ventilation Type
This alpha character string defines the type of ventilation as one of the following options: Natural, Exhaust, Intake, or Balanced. Natural ventilation is assumed to be air movement/exchange as a result of openings in the building façade and will not consume any fan energy. Values for fan pressure and efficiency for natural ventilation are ignored. For either Exhaust or Intake, values for fan pressure and efficiency define the fan electric consumption. For Natural and Exhaust ventilation, the conditions of the air entering the space are assumed to be equivalent to outside air conditions. For Intake and Balanced ventilation, an appropriate amount of fan heat is added to the entering air stream. For Balanced ventilation, both an intake fan and an exhaust fan are assumed to co-exist, both having the same flow rate and power consumption (using the entered values for fan pressure rise and

fan total efficiency). Thus, the fan electric consumption for Balanced ventilation is twice that for the Exhaust or Intake ventilation types which employ only a single fan.

Also, the Zone ventilation outputs according to the I/O reference (Page 402) says:

HVAC,Sum,Zone Ventilation Sensible Heat Loss [J]
HVAC,Sum,Zone Ventilation Sensible Heat Gain [J]

HVAC,Sum,Zone Ventilation Latent Heat Loss [J]
HVAC,Sum,Zone Ventilation Latent Heat Gain [J]
HVAC,Sum,Zone Ventilation Total Heat Loss [J]
HVAC,Sum,Zone Ventilation Total Heat Gain [J]

HVAC,Average,Zone Ventilation Volume Flow Rate Current Density [m3/s]
HVAC,Average,Zone Ventilation Volume Flow Rate Standard Density [m3/s]
HVAC,Sum,Zone Ventilation Volume Current Density [m3]

HVAC,Sum,Zone Ventilation Volume Standard Density [m3]
HVAC,Sum,Zone Ventilation Mass [kg]
HVAC,Average,Zone Ventilation Air Change Rate [ach]
HVAC,Sum,Zone Ventilation Fan Electric Consumption [J]

HVAC,Average,Zone Ventilation Inlet Air Temperature [C]

This is what led me to believe that I could ask for the output. But I am confused as to, should I define a separate Fan object and connect it to two nodes in order to get the electric consumption? The reason why I ask you this is because in my .IDF i havent actually defined a separate fan or separate nodes for that matter. But since the Ventilation:DesignFlow object asks for Fan parameters I thought the output would be generated automatically.

I hope I am making sense. Please excuse my really long copy paste from the I/O reference manual and also do take your time responding to this post. Good luck on your project today.

Niraj

On Mon, Jul 16, 2012 at 1:25 PM, CleanTech Analytics <jeremiah@xxxxxxxxxxxxxxxxxxxxxx> wrote:

Narj,
I do not think you can get night ventilation from design flow rate.

What I think you need to do is have a fan connected to an outdoor air node, and setup with an availability manager. There are a couple example files for this that come with e+..

To use them I think you would need to use a HVAC template, I find the heat pump to be strait forward. I am busy with a project today but will look for the files I used for similar and send them to you when I dig them up..

Jeremiah D. Crossett
CleanTech Analytics
503-688-8951

www.cleantechanalytics.com

This document may contain valuable information proprietary to CleanTech Analytics which is private and confidential. It may not be shared, copied, stored or transmitted in any form without the prior written consent of CleanTech Analytics

On Mon, Jul 16, 2012 at 9:55 AM, Niraj Poudel <nirajpdl@xxxxxxxxx> wrote:

Dear all,

I have modeled an office room with night time forced ventilation that turns on when the outdoor temperature is 2 degrees below the indoor temperature. Since I am not familiar with HVAC systems I am having difficulty obtaining the fan electric consumption using an ideal air loads system. I have attached my .IDF file to this email. If anyone has the time to look at the Ventilation Object and help me figure out the "Zone Ventilation fan electric consumption" I would greatly appreciate it.

Furthermore, the I/O Reference states that when using the balanced "ventilation type" as opposed to intake or exhaust, the fan electric consumption would be twice that of intake or exhaust. When in fact, intuitively it seems as though if you have two fans working in tandem (one intake, one exhaust = Balanced) each fan only needs to work half as much if there were only one fan, to get the job done?

Thanking you,
Niraj Poudel

--
Niraj Poudel, Architectural Engineer.
PhD student, PDBE Program.
Clemson University, Clemson, SC.

--
Niraj Poudel, Architectural Engineer.
PhD student, PDBE Program.
Clemson University, Clemson, SC.

--
Vinay Dev

Niraj Poudel, Architectural Engineer.

PhD student, PDBE Program.

Clemson University, Clemson, SC.