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[EnergyPlus_Support] Re: Ventilation Requirements per ASHRAE 90.1 Appendix G with a DOAS system



Jim,

For a 100% Outdoor Air System (Proposed) the formula is:

   Vot = Sum(Voz) 'Sum of the zone

For Multi-Zone Recirculating (Baseline) the formula is:

   Vot = Vou/Ev  'Uncorrected outdoor air rate / Ventilation efficiency

If we set the outdoor air requirements at the zone level (Voz) for both models to be equal, Vot of the Baseline will not equal Vot of the Proposed. 

This may not satisfy requirement of ASHRAE Appendix G3.1.2.6 for ventilation as states:

   Vot (Baseline) = Vot (Proposed)

If we force the issue and set the Vot of Baseline to the Vot of the Proposed, we will not meet the requirement of ASHRAE 62.1 for the Baseline model.

In addition, how is EnergyPlus reporting outdoor air because the two reports (Controller:OutdoorAir and Minimum Outdoor Air) are not consistent. I suspect that the Controller:OutdoorAir reports the Vou for a Multi-Zone Recirculating system, not the Vot.

Any insights would be appreciated.

CURTIS CLARK PE, LEED AP BD+C
SUSTAINABILITY SERVICES
GSBS Architects




--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Jim Dirkes" <jim@...> wrote:
>
> Dear Curtis,
> 
> I am not familiar with the report you mention.  Where does it come from? And
> what does it measure?
> 
> On the other hand, you seem to have answered at least part your own question
> by noting that minimums were identical for each of the two systems.  Can you
> run a 62.1 compliance check?  Or get it from the design engineer? To see if
> your minimum flows meet the 62.1 requirement?
> 
>  
> 
> The Building Performance Team
> James V. Dirkes II, P.E., BEMP , LEED AP
> 1631 Acacia Drive NW
> Grand Rapids, MI 49504
> 616 450 8653
> 
>  
> 
> From: EnergyPlus_Support@xxxxxxxxxxxxxxx
> [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of curtisjclark
> Sent: Tuesday, April 03, 2012 12:40 PM
> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> Subject: [EnergyPlus_Support] Re: Ventilation Requirements per ASHRAE 90.1
> Appendix G with a DOAS system
> 
>  
> 
>   
> 
> Each zone is hardwired using DesignSpecification:OutdoorAir object using
> "Flow/Area" values.
> 
> Curtis
> 
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx
> <mailto:EnergyPlus_Support%40yahoogroups.com> , Vinay Devanathan
> <vinay.devanathan@> wrote:
> >
> > You could hardwire the same OA cfm for each zone to what it is in the
> > design case.
> > 
> > On Tue, Apr 3, 2012 at 11:55 AM, curtisjclark <cjcfromslc@> wrote:
> > 
> > > **
> > >
> > >
> > > We are using a DOAS system which delivers 100% outdoor air to the space.
> > > In the Baseline model (appendix G), it is a VAV system which delivers
> mixed
> > > outdoor air with return air.
> > >
> > > To meet the requirements of ASHRAE 62.1 in the Baseline model, I used
> the
> > > Ventilation Rate Procedure calculation method to determine the minimum
> > > outdoor air by using the Controller:MechanicalVentilation object with
> the
> > > same ventilation rates as in the DOAS system.
> > >
> > > The report for "Controller:OutdoorAir" shows the two system have same
> > > Minimum Outdoor Air Flow Rate. However, the report "Minimum Outdoor Air
> > > During Occupied Hours" shows a 84% reduction in outdoor air.
> > >
> > > Have I meet the requirements of Appendix G3.1.2.6 for ventilation?
> > >
> > > 
> > >
> > 
> > 
> > 
> > -- 
> > Vinay Dev
> >
>



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