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

[Karen Walkerman]

I don't believe that the airflows between the proposed and baseline
designs need to be equal. System sizing and fan sizing needs to be
determined in the same way, but there are many things that affect
airflow and peak demand that may very well be different in the
proposed and baseline models, LPD, glass types, etc, although sizing
in the end may be determined by the 0.4 cfm/sf number. Also, when the
system is in heating mode, the as-designed fan power and flow should
be used. The last comment you just shared with us is definitely
incorrect.

--
Karen

On Tuesday, June 21, 2011, Will Mak <wmak at epsteinglobal.com> wrote:
> Bill, Seems like that will be the new default advice on how to deal with a lot of these warehouse/storage type facilities that have heating only. It makes a lot more sense than manipulating with the airflows on the proposed design. Since the project has already been submitted and we are already at the Final Design Review stage, I probably won’t change the system types in order to prevent even more confusion for the review team. William Mak, LEED AP BD+C
> Mechanical Design Engineer
>
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> þ Epstein is a firm believer in sustainability. We ask that you please consider the environment before printing this e-mail. From: Bishop, Bill [mailto:wbishop at pathfinder-ea.com]
> Sent: Tuesday, June 21, 2011 9:30 AM
> To: Will Mak; Timothy Moore; Karen Walkerman
> Cc: bldg-sim at lists.onebuilding.org
> Subject: RE: [Bldg-sim] Modeling Same Airflow on Proposed and Baseline Models Will, At the risk of confusing things even further, I recently received the following LEED review comment for a LEED 2.2 project:“Any heated-only spaces in the Proposed building must be modeled as heating-only in both buildings or as heated and cooled in both buildings. Please revise the Proposed and Baseline buildings as necessary to model the heated-only spaces identically in both buildings, and update the template accordingly. Although not required, it is encouraged that the ASHRAE 90.1-2010 Appendix G modeling protocols for heated-only spaces be followed using System Type 9.” As Timothy mentioned, System Type 9 would appear to apply to your case, and my LEED Reviewer’s comment gives you a basis for modeling both baseline and proposed as heating only if you choose to, even though that option was not available until 90.1-2010. Regards,Bill <thismessage:/mail/s/?view=att&th=130b2c87be417a2d&attid=0.1&disp=emb&zw> From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Will Mak
> Sent: Tuesday, June 21, 2011 10:18 AM
> To: Timothy Moore; Karen Walkerman
> Cc: bldg-sim at lists.onebuilding.org
> Subject: Re: [Bldg-sim] Modeling Same Airflow on Proposed and Baseline Models Thanks for all the feedback! Timothy, you gotta stop working so darn late!! I was thinking that I could respond to the comments stating that ASHRAE 90.1-2007 states that cooling capacities are suppose to be the same, airflows do not necessary have to be equal. I left out the part of the review that frustrated me the most: Due to these issues, the fan power consumption energy value in the Proposed model will be set equal to the fan power consumption energy value in the Baseline model; therefore the revised total electric consumption for the Proposed model will be increased by 2,451,577.5 kWh (3,565,295.5 kWh – 1,113,718 kWh), and the total energy cost for the Proposed model must be increased by $171,610.4 (2,451,577.5 kWh * $0.07/kWh) The revised Proposed total energy cost is $ 367,627.8 ($196,017.42 + $171,610.4). This leads to a total percentage cost savings improvement of 19.8%. The total predicted annual energy consumption for the project is 4,411,526.5 kWh (electricity) and 66,091 therms (natural gas). Basically, they went with the assumption that fan energy consumption must be equal on both and forced us to accept results they feel are correc