[Equest-users] Supply Fan Power

[Patrick J. O'Leary, Jr.]

it reads to me that your initial interpretation is what the reviewer is 
asking for.  on the other hand the question is what is constituting an 
"independent" exhaust fan here.  if the exhaust fan is part of the 
balance of the supply/return/exhaust system it probably should be 
modeled as such as it is not really different than having a return fan 
installed in the ductwork somewhere and not in a unit itself.  per hte 
90.1 user's manual (page g-28 in 2004), "System fan electrical power for 
supply, return, exhaust and relief fans is calculated based on the 
following formula.  The power from this formula includes supply, return, 
relief, and exhaust fans ..."   if the exhaust fan is not part of the 
designed system supply/return/exhaust then i would think your initial 
interpretation of what the reviewer is asking is correct.  whichever 
situation applies make sure the response documents the purpose of the 
exhaust fans and how 90.1 applies (including section/user manual 
references).

On 5/20/11 6:15 AM, M. Shields wrote:
>
> The exact comment is this:
>
> "The fan power spreadsheet for the Baseline and Proposed models 
> indicate that the fan power of the exhaust fans have not been modeled 
> identically in each model. All independent fan systems of the HVAC 
> systems in the actual design must be modeled identically between the 
> Proposed and Baseline models at actual equipment capacities (fan 
> volume and fan power) as required by Table G3.1.10 in the Proposed 
> building column, since the fan design air flow rates and fan power per 
> Sections G3.1.2.8 and G3.1.2.9, respectively, only applies to system 
> types 1 through 8 in Table G3.1.1A. If appealing this credit, revise 
> the Proposed and Baseline models so all independent fan systems of the 
> HVAC systems are modeled identically between the Proposed and Baseline 
> models. In addition, separate the energy consumption and peak demand 
> energy for independent fans in Table 1.8.1 and Table 1.8.2 of the 
> template and provide revised SV-A reports for each model reflecting 
> the changes."
>
> I initially interpreted this to be that for exhaust systems the bhp/kw 
> needs to be identical in both buildings and based on the specified 
> equipment from the mechanical designer, however, my supply fan energy 
> was Ok.  After reading the comment and Appendix G I am not unsure if I 
> also need to specify the fan power to be the same for both models, ie 
> use table G3.1.2.9 to calculate fan power for both instead of just the 
> baseline.
>
> *From:* equest-users-bounces at lists.onebuilding.org 
> [mailto:equest-users-bounces at lists.onebuilding.org] *On Behalf Of 
> *Patrick J. O'Leary, Jr.
> *Sent:* Friday, May 20, 2011 8:57 AM
> *To:* equest-users at lists.onebuilding.org
> *Subject:* Re: [Equest-users] Supply Fan Power
>
> from your wording of "independent" it sounds like you may have an 
> application where you have a unit in the proposed building that is 
> required but not provided in the design?  or something similar.  is 
> this the case?  if a unit is required in the proposed per the 
> requirement all spaces be heated/cooled (per the definitions) they are 
> required to be the same as the units in the baseline building.  if 
> this is not the case if you post the exact comment it may shed some 
> light on the subject.  otherwise i would argue the comment is in error 
> - if all of your zones are served by units in the proposed and you 
> have matching units in the baseline (regardless of system types) then 
> your approach would be correct.
>
> On 5/20/11 5:31 AM, M. Shields wrote:
>
> Good Morning All,
>
> I recently received comments back from LEED and one of them was about 
> my fan power.  In the submission I calculated all of my fan power 
> using G3.1.2.9 for the baseline building, and I used the actual fan 
> power in the proposed building.  The reviewer has commented that all 
> independent fan systems have to be modeled identically in both the 
> baseline and the proposed building.  The supply fans use very high 
> efficiency motors, and as such are substantially more efficient than 
> the calculation that G3.1.2.9 provides.  Is there no way to take 
> credit for using high efficiency supply fans?
>
> Thanks,
>
> ____________________________
> Michael Shields
>
> Email: mshields at fstrategies.com <mailto:mshields at fstrategies.com>
>
>   
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