[Equest-users] Confirmation for finding the Baseline Energy Model Supply Airfllow

[Carol Gardner]

You must use the 1.15 and 1.25 multipliers to meet LEED requirements. I
would look at the throttling range that eQ is defaulting to. if it's .5 F,
which is I think what it is for PSZ, I would raise that to1 or 2 F, which is
reasonable. Then I would look at the space loads, equipment especially and
make sure all that looks good, then I'd look at the schedules, make sure
they are good, and then I'd look at the cfm/sf. It's not unreasonable to
match it to your proposed building and I don't know of any issue LEED has
with doing that.

Carol

On Tue, Sep 7, 2010 at 4:23 PM, Kathryn Kerns <
kathryn.kerns at bceengineers.com> wrote:

>
>
> Yes, Carol I know the default airflow value is very low. Usually the eQuest
> airflow auto sizing routine will select larger values than the default. The
> problem is: what if the eQuest baseline energy model selects airflows larger
> than the default cfm/sqft airflow values but the baseline energy model still
> ends up with greater than 300 unmet hours or the baseline energy model has
> more than 50 unmet hours greater than the proposed energy model?
>
>
>
> Do you start increasing the baseline energy model airflows above the auto
> sized airflow value in the thermal blocks that are having unmet hours
> issues, or do you retain the auto sized airflow value and start manually
> increasing the baseline heating and cooling capacities that were also auto
> sized by eQuest using the 1.15 and 1.25 oversized coefficients?
>
>
>
>
>
> *Kathryn Kerns*
>
> *Systems Specialist*
>
> *BCE** Engineers, Inc.*
>
> *| Ph: 253.922.0446 | Fx: 253.922.0896 |*
>
>
>
>
>  ------------------------------
>
> *From:* Carol Gardner [mailto:cmg750 at gmail.com]
> *Sent:* Tuesday, September 07, 2010 2:22 PM
> *To:* Kathryn Kerns
>
> *Cc:* equest-users at lists.onebuilding.org
> *Subject:* Re: [Equest-users] Confirmation for finding the Baseline Energy
> Model Supply Airfllow
>
>
>
> Kathryn,
>
>
> I think that .5 cfm/sf is too low. I never saw it used when I was designing
> HVAC systems except for an occasionally used interior space. I immediately
> change it to1.0 cfm/sf which I feel is a good place to start. For highly
> loaded rooms with lots of internal gain I sometimes up that amount after I
> have checked the other possible inputs.
>
> Carol
>
> On Tue, Sep 7, 2010 at 1:55 PM, Kathryn Kerns <
> kathryn.kerns at bceengineers.com> wrote:
>
>
>
> Everyone,
>
>
>
> We are having a discussion at the office about how to define the supply
> airflow and energy model baseline. I pick the baseline system type per
> Appendix G (packaged single zone, packaged VAV, etc., set the heating sizing
> ratio to 1.25 and the cooling sizing ratio to 1.15, leave the heating and
> cooling capacities blank so the model will auto-size, and then set the
> default airflow to 0.5 cfm/sqft and let eQuest run. I then check to see if
> the baseline energy model unmet hours are less than 300 and are within 50
> hours of the proposed model. If the baseline energy model is above 300 unmet
> hours or isn’t within 50 hours of the proposed model, I will then start
> tweaking the airflow in the baseline energy model thermal blocks that are
> causing the unmet hour issues to solve the problem.
>
>
>
> Is this what everyone else is doing or do leave the airflow with the
> default values it calculated with the 0,5 cfm/sqft limit and enter capacity
> values in the previously blank HVAC cooling and heating capacities slots so
> the baseline energy model stops auto-sizing?
>
>
>
> Thanks.
>
>
>
>
>
> *Kathryn Kerns*
>
> *Systems Specialist*
>
> *BCE** Engineers, Inc.*
>
> *| Ph: 253.922.0446 | Fx: 253.922.0896 |*
>
>
>
>
>
>
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>
>
>
> --
> Carol Gardner PE
>



-- 
Carol Gardner PE
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