Re: [EnergyPlus_Support] OA

On Sat, Jun 4, 2011 at 7:45 AM, YuanLu Li <yli006@xxxxxxxxxxx> wrote:

Use a ventiltion object to feed the amount of air you want and llink it to the equipment and/or hot water usage object.

For example, when the shower hot water is on, turn on the ventilation at the same time.
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I have mentioned to you before, if you wanted to control the zone air feed with a VAV damper, you must have an air by by-pass path, just like the bypass water branch in the water loop.
CBVAV model provides a by pass damper function.

That was the reason for the AHU to adjust the air flow to 1 for the controlled zone, because you were using constant volume fan and fixed dampers. (Uncontrolled ATU)

Dr. Li

To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: vinay.devanathan@xxxxxxxxx
Date: Fri, 3 Jun 2011 21:18:55 -0400

Subject: Re: [EnergyPlus_Support] OA - Zone Level

Okay. But how to go about modelling an intermittent OA Supply and Exhaust for Kitchen, Bathrooms etc. in a residential unit on top per person calculation?

On Fri, Jun 3, 2011 at 9:06 PM, YuanLu Li <yli006@xxxxxxxxxxx> wrote:

You are back to your original design question.

What is the real OA need per zone? This is taken care off by the minimum air flow rate in the AHU and the air leak of the building, unles you are designing a hospital OR cluster will filtered air..

If you must have a separate feed, use an AHU and a group of uncontrolled ATU's per zone.

The template four pipe fan coil has its own OA intake per zone.

Dr. Li

To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: vinay.devanathan@xxxxxxxxx
Date: Fri, 3 Jun 2011 20:56:43 -0400
Subject: Re: [EnergyPlus_Support] OA - Zone Level

Dr. Li,

Thanks for your reply.

I follow your method of specifying OA controls. But it arises one more question to me, how would a multi-zone system's OA controller distribute OA supply to each zone as per its individual needs? I am not able to find an answer for that.

Vinay

On Fri, Jun 3, 2011 at 8:27 PM, YuanLu Li <yli006@xxxxxxxxxxx> wrote:

The simple answer is yes, and you need not use EMS to control the OA inlet node actuator.

The following is from page 1670 of the I/O Ref Manual.

Controller:OutdoorAir,

OA Controller 1, !- Name

Relief Air Outlet Node, !- Relief Air Outlet Node Name

Outdoor Air Mixer Inlet Node, !- Return Air Node Name

Mixed Air Node, !- Mixed Air Node Name

Outdoor Air Inlet Node, !- Actuator Node Name

0.25, !- Minimum Outdoor Air Flow Rate {m3/s}

1.6, !- Maximum Outdoor Air Flow Rate {m3/s}

ElectronicEnthalpy, !- Economizer Control Type

ModulateFlow, !- Economizer Control Action Type

23., !- Economizer Maximum Limit Dry-Bulb Temperature {C}

, !- Economizer Maximum Limit Enthalpy {J/kg}

13.5, !- Economizer Maximum Limit Dewpoint Temperature {C}

ElectronicEnthalpyCurveA,!- Electronic Enthalpy Limit Curve Name

14., !- Economizer Minimum Limit Dry-Bulb Temperature {C}

NoLockout, !- Lockout Type

FixedMinimum, !- Minimum Limit Type

OAFractionSched, !- Minimum Outdoor Air Schedule Name

, !- Minimum Fraction of Outdoor Air Schedule Name

, !- Maximum Fraction of Outdoor Air Schedule Name

, !- Mechanical Ventilation Controller Name

TimeOfDayEconomizerSch, !- Time of Day Economizer Control Schedule Name

Yes, !- High Humidity Control

EAST ZONE, !- Humidistat Control Zone Name

0.9, !- High Humidity Outdoor Air Flow Ratio
Yes; !- Control High Indoor Humidity Based on Outdoor Humidity Ratio

Curve:Cubic,

          ElectronicEnthalpyCurveA,!- Name

0.01342704, !- Coefficient1 Constant

-0.00047892, !- Coefficient2 x

0.000053352, !- Coefficient3 x**2

-0.0000018103, !- Coefficient4 x**3

16.6, !- Minimum Value of x

29.13; !- Maximum Value of x

=================
You need not use all the fields. There may be a simpler one without the economizer section. It has the option to use the sum of the minimum, and people, equipment, etc of the zone.
Controller:MechanicalVentilation
=======================
I do not quite follow your question with the Zone sizing - using the DesignSpecification:OutsideAir object. Zone sizing controls the equipment capacity. It will include the load demands, but do not vary the flow rate according to a schedule.

Dr. Li

To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: vinay.devanathan@xxxxxxxxx
Date: Fri, 3 Jun 2011 18:28:21 -0400
Subject: [EnergyPlus_Support] OA - Zone Level

Hello,

I would like to know if it is possible to specify Outdoor Air demand at Zone Level with the use of a Schedule. For example, a schedule or a pattern describing the demand for different OA Supply CFM at different times in the Zone Level? The only way to specify OA cfm to zones is using the Sizing:Zone object (excluding VAV system - which can use the DesignSpecification:OutsideAir object). Am I correct? Is there any other way to override this and introduce OA supply to the zones? Can this be done using EMS?

Thank you.

Vinay