[Equest-users] Baseline Fan power calculation

vamshi ranga vamshiranga at gmail.com
Tue Mar 26 05:07:18 PDT 2013


Hi,

Thanks, but it is difficult to understand (some confusion). Let's say the
Proposed system has following specifications

Supply fan cfm = 40000
Supply fan Wattage = 20000
Return fan cfm = 35000
Return fan Wattage = 18000
Filter used = MERV 12
Exhaust fan cfm = 5000
Exhaust fan Wattage = 2500

And Baseline (0 deg orientation) has following specifications when
simulated with default fan kW/cfm and 20 deg F difference,

Supply fan cfm = 30000
Supply fan Wattage = 15000
Return fan cfm = 25000
Return fan Wattage = 13000

1. Please tell me how to distribute kW/cfm in basecase and from where will
I get baseline default exhaust specification?
2. Won't the change in baseline when we input calculated value in eQUEST
due to heat gain
3. Should we take all the 4 orientations average cfm for calculating
baseline cfms
4. Tell me how to calculate baseline fan power from above values

If, this example is confusing. I request you to give your own example for
understanding.
I have been having doubt related to fan power calculation. I am eager to
learn how to do it properly to avoid any GBCI comments.

Your valuable time put in resolving my doubt is appreciated.

Thanks,
Vamshi.


On Tue, Mar 26, 2013 at 3:23 PM, Cam Fitzgerald <cam at energyopportunities.com
> wrote:

> All,****
>
> ** **
>
> It seems there is much confusion on this issue. The Proposed fans are all
> modeled explicitly (with the fan power as designed). In the Baseline case
> each HVAC system fan power (Section G3.1.2.9)  is calculated using the
> supply airflow (Section G3.1.2.8) based on 20 F space to supply air
> temperature difference. If the Proposed system uses multiple fans, then the
> calculated system fan power is distributed among the fans in the Proposed
> design. Appendix G does not provide any guidance for how this power should
> be distributed among the system fans in the Baseline system, but usually
> projects use the same proportion of the total system fan power as the
> Proposed design. All the fan power can be modeled as a single supply fan,
> but that will apply all the heat gain from the fan to the supply airstream
> which may not be realistic for large systems. Note that exhaust fans in the
> Proposed design that operate continuously during occupied periods are
> considered part of the system and their power is included in the calculated
> Baseline fan power. Exhaust fans that operate intermittently are considered
> a process load and must be modeled identically in both cases. If the
> Proposed process exhaust fan motor is larger than one HP, the motor
> efficiency is regulated by  Section 10 and savings may be claimed for using
> high efficiency motors as compared to the minimum efficiency from Table
> 10.8.****
>
> ** **
>
> Hope this helps!****
>
> ** **
>
> Cam Fitzgerald****
>
> ** **
>
> Energy Opportunities/a 7group company****
>
> ** **
>
> ** **
>
> ** **
>
> ** **
>
> *From:* equest-users-bounces at lists.onebuilding.org [mailto:
> equest-users-bounces at lists.onebuilding.org] *On Behalf Of *vamshi ranga
> *Sent:* Tuesday, March 26, 2013 3:27 AM
> *To:* Nick Caton
> *Cc:* equest-users at lists.onebuilding.org
> *Subject:* Re: [Equest-users] Baseline Fan power calculation****
>
> ** **
>
> Dear Nick Caton,****
>
> ** **
>
> Thank you very much for valuable inputs, from this it is clear that, ****
>
> ** **
>
> 1. However there are different motors used in Proposed case for supply,
> return and exhaust with different kW/cfm, we need to use one single motor
> in with one kW/cfm in baseline case****
>
> 2. In EAp2 Section 1 4 Tables of LEED under "Table 1.4.2", it asks
> for separate wattage of supply, return and exhaust fans in baseline case,
> So, there we need to enter as "Not Applicable"****
>
> ** **
>
> Please let me know if my understanding is wrong.****
>
> ** **
>
> Thanks,****
>
> Vamshi.****
>
> ** **
>
> On Mon, Mar 25, 2013 at 8:04 PM, Nick Caton <ncaton at smithboucher.com>
> wrote:****
>
> Hi Vamshi,****
>
>  ****
>
> I advise carefully reviewing the footnotes under Table 6.5.3.1.1A, which
> include procedure for determining baseline fan power adjustments.****
>
>  ****
>
> 1.       Pfan represents the sum power of all fans in a given baseline
> system (with exception to baseline systems #6/#8, fan powered VAV boxes).*
> ***
>
> 2.       Again, there is not a separate supply/return power calculation
> (see answer #1).  You can however account for adjustments present in
> separate airstreams from the proposed design.  ****
>
> 3.       Probably not.  Review the difference between CFMS and CFMDcarefully at the cited Table.  A CFM quantity representing the airflow each
> element encounters (CFMD) should be applied against each pressure drop
> adjustment, not an ‘aggregate’ of supply+return.  ****
>
>  ****
>
> You may also find the attached resource published by 7group helpful to
> cement your procedural understanding of how to arrive at the sum total for
> “A.”  ****
>
>  ****
>
> Regards,****
>
>  ****
>
> ~Nick****
>
> [image: cid:489575314 at 22072009-0ABB]****
>
> * *****
>
> *NICK CATON, P.E.*****
>
> SENIOR ENGINEER****
>
>  ****
>
> Smith & Boucher Engineers****
>
> 25501 west valley parkway, suite 200****
>
> olathe, ks 66061****
>
> direct 913.344.0036****
>
> fax 913.345.0617****
>
> www.smithboucher.com* *****
>
>  ****
>
> *From:* equest-users-bounces at lists.onebuilding.org [mailto:
> equest-users-bounces at lists.onebuilding.org] *On Behalf Of *vamshi ranga
> *Sent:* Monday, March 25, 2013 8:17 AM
> *To:* equest-users at lists.onebuilding.org
> *Subject:* [Equest-users] Baseline Fan power calculation****
>
>  ****
>
> Hi All,****
>
>  ****
>
> I have a doubt regarding calculating fan power as per ASHRAE 90.1-2007.***
> *
>
>  ****
>
> My proposed system has, supply return and exhaust fans separately with kW
> and cfm mentioned for each fan.****
>
>  ****
>
> So, for calculating baseline fan power, ****
>
>  ****
>
> 1. should I calculate it separately for each fan type? ****
>
> 2. can I take pressure drop adjustment both in supply and return fan power
> calculation?****
>
> 3. should I sum all the cfms of supply, return and exhaust and than apply
> pressure drop adjustments to aggregated cfm.****
>
>  ****
>
> Kindly help me out in solving the doubt. If you have any example fan power
> calculations, or web links those could guide me regarding this, plz do
> share them.****
>
>  ****
>
> Thanks in advance.****
>
>  ****
>
> Regards,****
>
> Vamshi.****
>
> ** **
>
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