[Equest-users] LEED Increased Ventilation Credit and Energy Modeling

[Robby Oylear]

Joe,

Your last bit there about taking credit for constant OA flow from full-load
to part-load conditions on a VAV system is a bit of a red flag for me.  The
Baseline system should be minimally compliant with ASHRAE 62.1.  ASHRAE
62.1 section 6.2.6.1 requires that ventilation systems shall be designed to
be capable of providing the required ventilation rates in the breathing
zone including all full- and part-load conditions.  Outside of Demand
Control Ventilation scenarios, I would always expect the Baseline and
Proposed case to deliver the same outside airflow at all hours.

That being said, I'm not certain how you're actually getting a credit for
what you're saying.  What input are you modifying in eQUEST to accomplish
proportional outside air flow control?

-Robby


On Thu, Mar 6, 2014 at 1:48 PM, Joseph Lewis
<jlewis at fortierengineering.com>wrote:

>   You are going to follow 90.1 Appendix G for the model.  This means both
> the baseline and proposed design outdoor air flow rates will need to be the
> same except if you are using demand control ventilation in the proposed and
> it is not required by 90.1 section 6.
>
> In the case where you have demand controlled ventilation in the proposed
> and it is not required in the baseline then the USGBC has stated that they
> would like the baseline to be modeled as compliant with 62.1 without the
> system level corrections.  There also should not be any temperature
> difference corrections because the other appendix G rules require your CFM
> sizing to be based up on a 20 °F delta T.
>
> If demand controlled ventilation is required by 90.1 then it must be
> modeled in the baseline and proposed with the same design flow.
>
> I personally take credit on my models for where the proposed VAV system
> has controls to maintain a constant OA flow across from design to minimum
> supply, by modeling the baseline as just proportional.  I have not been
> flagged for it, but I also have not found any definitive ruling that what I
> am doing is allowed.
>
> Joe Lewis
> Fortier Engineering
>
>  *From:* Joe Chappell <JoeC at designengineers.com>
> *Sent:* Thursday, March 06, 2014 3:50 PM
> *To:* mailto:equest-users at lists.onebuilding.org<equest-users at lists.onebuilding.org>
> *Subject:* [Equest-users] LEED Increased Ventilation Credit and Energy
> Modeling
>
>
> Good day,
>
>
>
> I have a question regarding the LEED credit for Increased Ventilation
> (IEQc2).  This is the credit awarded for exceeding ventilation in all
> spaces by 30% beyond the ASHRAE standard 62.1 requirements.  It seems
> obvious that the design model ventilation rates would be those 30% higher
> than 62.1 requirements.  What then would the baseline model ventilation
> rates be?
>
>
>
> If you strictly follow 90.1 Appendix G, you should always model baseline
> and proposed equivalent except for when taking credit for demand controlled
> ventilation.  However, it seems in this case that it could also be argued
> (by LEED) that you should model the ASHRAE 62.1 required ventilation rates
> in the baseline model, not those that are 30% higher and therefore pay the
> energy expense( most climates) for increased outside air.
>
>
>
> Does anyone have any experience with LEED on this issue?  Thanks in
> advance.
>
>
>
> Kind regards,
>
> *Joe Chappell*
>
>
>
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