[Equest-users] Minimum design airflow in e-QUEST for Baseline and Proposed design

[Javed Iqbal]

Dear Nimesh,

For baseline refer G3.1.3.13 VAV Minimum Flow Setpoints (Systems 5 and 7).
Minimum volume setpoints for VAV reheat boxes shall be 0.4 cfm/ft2 of floor
area served or the minimum ventilation rate, whichever is larger.

For proposed it depends on the Internal load of the space. For zone with
high internal load you may need to increase your CFM upto 1-1.2 CFM.Sqft.
OR you can also give direct supply CFM as per design and make sure you also
includes altitude factor in your inputs.

Thanks!

On Fri, Aug 3, 2012 at 2:00 AM, nimesh.prajapati <
nimesh.prajapati at hitechcaddservices.com> wrote:

> Dear Javed,****
>
> Can you please help me?****
>
> This refers to the Minimum design airflow in e-QUEST for Baseline and
> Proposed design.****
>
> I am still not confident how to calculate minimum design airflow for
> baseline and Proposed model.****
>
> Minimum Design Air Flow is used to set a "floor" (i.e., minimum) on the
> design air flow supplied to each space. This is not to be confused with VAV
> Minimum Air Flow. Minimum Design Air Flow pertains to air flow at design
> (maximum) conditions. VAV Minimum Air Flow indicates how far closed hourly
> air flow can modulate under low load (off-design) conditions. ****
>
> The default Minimum Design Air Flow is based on System Type. If Zoning
> Pattern = "Perimeter/Core", then two Minimum Design Air Flows are
> available, one for core zones, the other for perimeter zones. ****
>
> Minimum Design Air Flow can have a profound impact on fan energy use if
> set too high. Note that this is used to set a "floor" or minimum on the
> design air flow supplied to each space. If the HVAC design performed by the
> simulation finds that more airflow than the Minimum Design Air Flow is
> necessary, it will specify the necessary design air flow rate. ****
>
> Conventional HVAC design often delivers air to spaces at a rate of about
> 1.0 CFM/sqft. When sizing air flow only to meet load requirements, it is
> not uncommon for a simulation program to find that design flow rates less
> than 0.5 CFM/sqft are adequate for lightly loaded spaces (e.g., some core
> spaces, circulation spaces, etc.). It is common practice to provide at
> least 0.5 CFM/sqft to each space to insure adequate ventilation and air
> movement for comfort. ****
>
> The default value in e-QUEST is 0.50 cfm/sqft.****
>
> I had gone through ASHRAE 90.1 guidelines but unable to find it.****
>
> Can you please guide me?****
>
> Thanks,****
>
>  ****
>
> Nimesh Prajapati****
>
>  ****
>
> (+91 9687133492)****
>
> HVAC Design Engineer & Energy Modeller****
>
> ** **
>



-- 


Javed Iqbal, LEED AP, CEA
Energy Analyst
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