[Bldg-sim] Fan power calculation for proposed model

[Jim Dirkes]

I agree with Cory.
The ASHRAE 90.1 committee would be hard pressed to integrate the different
manners that all modeling software could be used to come up with specific
simulated flow rates using unspecified (for the model) operating schedules
and internal loads.  The designer is already tasked with selecting the fan
using best available information, so I think that's a more reliable basis.

On Tue, Sep 1, 2015 at 5:08 PM, Duggin, Cory <Cory.Duggin at tlc-eng.com>
wrote:

> It is my understanding that the proposed model should always be the design
> values used in selecting the fan not what is calculated by the energy
> simulation.  I agree the fan most likely will not operate at that flow
> rate, but that is what we have fan curves for.
>
>
>
> *Cory Duggin, PE, LEED AP BD+C *
>
> *Associate/Energy Modeling Wizard, j.g.*
>
> *[image: GreenWeek2015_FINAL-Email-Sig]*
>
> *TLC Engineering for Architecture *
>
> direct:
>
> 615-346-1939
>
>
>
>
>
> *From:* Bldg-sim [mailto:bldg-sim-bounces at lists.onebuilding.org] *On
> Behalf Of *Nicholas Blanton
> *Sent:* Tuesday, September 01, 2015 4:03 PM
> *To:* bldg-sim at lists.onebuilding.org
> *Subject:* [Bldg-sim] Fan power calculation for proposed model
>
>
>
> Please comment on the following:
>
>
>
> Based on Table G3.1.10.a, for an HVAC system in the proposed design, the
> system is determined by the following:
>
>
>
> “Where a complete HVAC system exists, the model shall reflect the actual
> system type using actual component capacities and efficiencies.”
>
>
>
> In design of AHU systems, the scheduled or nameplate flow rate of the
> equipment is typically higher than the design flow rate of the system, as
> calculated by the simulation software. The system fan power calculation is
> based on the efficiency of the fan and ultimately the design flow rate of
> the fan. Also, in operation the fan typically does not operate at 60 Hz at
> peak flow rate, suggesting that the operating flow rate in this condition
> is more in line with the design flow rate calculated by the simulation
> software, rather than the nameplate flow rate of the equipment.
>
>
>
> For these reasons, it is likely the case that the fan power calculation
> should be based on the design flow rate calculated by the software, rather
> than the nameplate flow rate.
>
>
>
> Thanks,
>
>
>
> Nick Blanton
>
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-- 

James V Dirkes II, PE, BEMP, LEED AP
CEO/President
The Building Performance Team Inc.
1631 Acacia Dr, GR, Mi 49504

Direct: 616.450.8653
jim at buildingperformanceteam.com

Website <http://buildingperformanceteamcom>l  LinkedIn
<https://www.linkedin.com/pub/jim-dirkes/7/444/413>

The body must be given a little less than it needs. Otherwise it will turn
traitor.
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