[Bldg-sim] Modeling Same Airflow on Proposed and Baseline Models

[Karen Walkerman]

Will,

I actually think that the reviewer has a point here.  Your proposed design
has no cooling, therefore, the proposed design needs to have a cooling
system that is the same as the baseline system.  The airflows don't have to
be equal, but they have to be determined in the same fashion (auto-sizing
with a minimum flow of 0.4 cfm/sf).  HOWEVER, these rules should only apply
to the system in cooling mode. When in heating mode, the system can reflect
the designed values.


--
Karen

On Mon, Jun 20, 2011 at 8:59 PM, Timothy Moore <timothy.moore at iesve.com>wrote:

> Will,
>
>
>
> This reviewer appears to be seriously confused and has applied baseline
> rules to your proposed design model.
>
>
>
> You can do whatever you want with the fan sizing in the *proposed* model,
> so long as your have use identical space conditioning set points and
> schedules and results are *within* stated limits for maximum unmet load
> hours *and* you do not exceed the maximum difference in unmet hours
> between the baseline and proposed. This is to prevent you from having a *
> proposed* design that is under-cooled or under heated relative to the *
> baseline*.
>
>
>
> Similarly, the 0.4 CFM/SF requirement is for the *baseline* model, not the
> *proposed*.
>
>
>
> Regards,
>
> Timothy
>
>
>
>
>
> *[image: cid:image001.jpg at 01CBEDFA.628DACD0]* <http://www.iesve.com/>
>
> *Timothy Moore** **
> *Senior Product Manager
>
> Office: 415 983-0603
> timothy.moore at iesve.com
> www.iesve.com
>
>
> **Design, Simulate + Innovate with the <Virtual Environment>**
>
>     Email Disclaimer <http://www.iesve.com/disclaimer.html>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> *From:* [mailto:bldg-sim-bounces at lists.onebuilding.org] *On Behalf Of *Will
> Mak
> *Sent:* Monday, June 20, 2011 2:26 PM
> *To:*
> *Subject:* [Bldg-sim] Modeling Same Airflow on Proposed and Baseline
> Models
>
>
>
> Have any of you run into a review team telling you that you must model the
> baseline fan supply volume and baseline fan power the same in the proposed
> design? I have a project under review that is a distribution center
> primarily served by heating only make up air units. I have modeled cooling
> in both models and modeled the setpoint high enough that it would never turn
> on.
>
>
>
> My interpretation of the requirement to model cooling the same in both
> models if cooling does not exist on the proposed design is just that, you
> only model the cooling the same. However, this is the response we received
> after our initial design comments review:
>
>
>
> *2. The response narrative to preliminary comment 5 states that the
> baseline case was modeled with a fan supply volume determined using Section
> G3.1.2.8 and a fan power determined using Section G3.1.2.9; however the
> proposed case must also be determined using these parameters.  Per Table
> G3.1.10(d) in the proposed building column, where no cooling system exists,
> it must be modeled identically to the baseline case.  Because the fan
> supply volume and fan power are cooling driven, it is unacceptable to
> auto-size the baseline case fan supply volume and fan power and not
> auto-size the proposed case fan supply volume and fan power.  Currently,
> the baseline fan supply volume is sized to meet cooling needs and the
> proposed fan supply volume is sized to meet heating and ventilation needs.
> If appealing this credit, revise the Proposed case fan supply volume and
> fan power so that they are determined using Section G3.1.2.8 and Section
> G3.1.2.9.  Note that it is appropriate for the proposed fans to be modeled
> as VAV since HVAC System 7 applies.  Additionally, provide SV-A reports
> confirming the changes.*
>
>
>
> Another comment we received claimed that we must model the 0.4 CFM/SF
> requirement on the proposed model because the airflows are sized based on
> cooling and therefore, the airflow rules from System 7 apply (i.e. 20 delta
> T, min flow requirements, etc.)
>
>
>
> *3. The response narrative to preliminary comment 12 states that the full
> load equivalent hours are so high due to the 0.4 cfm/sq.ft flow rate;
> however the 0.4 cfm/sq.ft rate applies only when the building is occupied or
> when the interior fans are cycled on during unoccupied hours to meet heating
> or cooling loads.  Based on the information provided in Section 1.2 of the
> Prerequisite form the occupied hours are only 40 per week.  If appealing
> this credit, revise the schedules in both cases to reflect the actual
> anticipated schedules of the interior fans installed in the building.
> Additionally, revise the baseline case (and proposed case as necessary for
> equipment auto-sized per Table G3.1.10(d)) so that the 0.4 cfm/sq.ft minimum
> flow rate applies only when the building is occupied or when they are cycled
> on. *
>
>
>
> I already took care of the scheduling of the when the fans turned on.
> However, I honestly feel like the rest of both comments step over the line
> in terms of what we are suppose to model on the proposed design. The changes
> we would need to make (primarily forcing the airflows to be sized the same
> as the baseline and 0.4 cfm/sq ft) do not represent the design intent of the
> system shown on the drawings.
>
>
>
> What do you guys think?
>
>
>
> *William Mak, LEED AP BD+C*
> Mechanical Design Engineer
>
> *EPSTEIN*
> Architecture
> Interiors
> Engineering
> Construction
>
> Sustainability
>
> 600 West Fulton Street
> Chicago, Illinois 60661-1259
>
> D: (312) 429-8116
> F: (312) 429-8800
>
> E: wmak at epsteinglobal.com
> W: www.epsteinglobal.com
>
> þ Epstein is a firm believer in sustainability. We ask that you please
> consider the environment before printing this e-mail.
>
>
>
> _______________________________________________
> Bldg-sim mailing list
> http://lists.onebuilding.org/listinfo.cgi/bldg-sim-onebuilding.org
> To unsubscribe from this mailing list send  a blank message to
> BLDG-SIM-UNSUBSCRIBE at ONEBUILDING.ORG
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/bldg-sim-onebuilding.org/attachments/20110620/bfb8e951/attachment-0002.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: image/jpeg
Size: 1668 bytes
Desc: not available
URL: <http://lists.onebuilding.org/pipermail/bldg-sim-onebuilding.org/attachments/20110620/bfb8e951/attachment-0002.jpeg>