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NC-v4 EAp2:Minimum energy performance

Regd. pressure drop adjustments in baseline fan power calculator

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Anurag Ghosh
Assistant Sustainability Manager
L&T Construction
LEEDuser Basic Member
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Hello All,

I will generally put this question to Marcus. We generally use 7group's baseline fan power calculator to account for fan power and pressure rise accordingly. Now, I have some confusion regarding the pressure drop adjustments. If I have a fully ducted return air system with MERV9,13 filters, and sound attenuation section(in some marked locations), I would be using the coefficients 0.5,0.5,0.9 and 0.15 in the subsequent pressure drop adjustment column right?

Also, the design airflow through device would ideally be the same for all rows for accounting the pressure drop right?

Thanks in advance

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Marcus Sheffer
LEED Fellow
7group / Energy Opportunities
LEEDuser Expert
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Sat, 03/08/2025 - 15:46

I'll let the author of the spreadsheet, Tyler Thumma, answer your questions.
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Anurag Ghosh
Assistant Sustainability Manager
L&T Construction
LEEDuser Basic Member
2 thumbs up

Sat, 03/08/2025 - 16:29

Also, is the calculator accepted as LEED submittal document?

Mon, 03/10/2025 - 12:00

Keep in mind that the pressure drop adjustments should only be applied to the applicable device airflows. For example, if the sound attenuation is only designed for half of the Proposed system airflows, then this pressure drop adjustment should only be calculated using half of the Baseline airflows. The pressure drop adjustments applicable to a given airflow can all be added and reported within a single cell. In your example, if all pressure drop adjustments apply to the total supply airflow, you can enter 2.05 as the Table 6.5.3.1.1B Pressure Drop Adjustment (PD) and the Baseline supply airflow as the Design Airflow Through Device (CFMD). However, adjustments which apply to differing airflows must be reported in separate rows.

Mon, 03/10/2025 - 12:01

The calculator is accepted but is unnecessary because the Baseline fan power calculations are now included within the Minimum Energy Performance Calculator Air-Side HVAC tab.
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Anurag Ghosh
Assistant Sustainability Manager
L&T Construction
LEEDuser Basic Member
2 thumbs up

Tue, 03/11/2025 - 11:57

Hi Tyler, suppose we have system 8 which describes using single HVAC system per floor. Now,after running the baseline peak cooling load simulation, we get the total design airflow rate per floor. Suppose we do have sound attenuation section for half of actual design system airflows, do we half the baseline air flow rates for all the floors? Also, some propsoed airflows may be designed with MERV and HEPA filters specially in the critical spaces while other noncritical spaces may not be. Do we count and proportion the baseline flow rates based on total no of filters to total no of system airflows?

Thu, 03/13/2025 - 12:36

Yes, you would apply the sound attenuation pressure drop adjustment to half of the Baseline airflows if that is the proportion with sound attenuation in the design. Similarly, the filtration pressure drop adjustments would be applied to the same proportion of Baseline airflows as the design. 

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