[Equest-users] LEED Comment for FAN EFLH--help please

[Bishop, Bill via Equest-users]

Pasha,
In addition to my questions below, you can affect the air flow for VAV systems using different cooling controls.
Besides the minimum VAV  box setting of 0.4 cfm/ft2 per G3.1.3.13, there is also the temperature reset requirement of G3.1.3.12.
The 5°F reset requirement can be set using a COOL-CONTROL of WARMEST and a 5°F difference between the COOL-MIN-RESET-T and the COOL-MAX-RESET-T.
Then, using a RESET-PRIORITY of AIRFLOW-FIRST, the system airflow will be reduced before the cooling SAT.
~Bill

From: Bishop, Bill
Sent: Thursday, March 30, 2017 4:05 PM
To: 'Pasha Korber-Gonzalez' <pasha.pkconsulting at gmail.com>
Subject: RE: [Equest-users] LEED Comment for FAN EFLH--help please

Hi Pasha,
I would put the question back on you – what is the cause of the difference in EFLH?

-        Does the proposed design feature VFD while the baseline doesn’t, or does it use a lower MIN-FLOW-RATIO?

-        Does the proposed design feature a controls strategy such as DCV?

-        Does the proposed design require fewer fan cycling hours during unoccupied periods?

o   due to an improved envelope?

o   Or by using radiant heating systems instead of the air-side ventilation system?

-        Does the baseline run at a higher percentage of full-flow in cooling due to higher sensible loads (higher LPD for example)?
Etc.
Regards,
~Bill

William Bishop, PE, BEMP, BEAP, CEM, LEED AP | Pathfinder Engineers & Architects LLP
Senior Energy Engineer

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From: Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Pasha Korber-Gonzalez via Equest-users
Sent: Thursday, March 30, 2017 3:52 PM
To: eQUEST Users List <equest-users at lists.onebuilding.org<mailto:equest-users at lists.onebuilding.org>>
Subject: [Equest-users] LEED Comment for FAN EFLH--help please

Hello fellow eQuesters,

I'm sure we all get the standard LEED review comment regarding Fan equivalent full load hours (EFHL).

I received this one on my current project (elementary school in Ohio with heat recovery units.)  I have confirmed that my fan schedules for both models are exactly the same.  But I do have drastically different EFLH values for the baseline (over 3,000) and proposed (less than 1,500).

I have made changes in my models, but I cannot seem to get the proposed hours over 1,600 of run time.

QUESTION:  Do any of you have any experience of suggesting to the LEED Reviewer that it is possible to have this significant of difference between the two models hvac systems AND how can I show justification for these run hours??  Any advice & suggestions are welcomed at this time.

Here is the LEED comment I received with highlighted notes:
. Table EAp2-5 of the form indicates that the equivalent full load hours for interior fans in the Proposed and Baseline model are 1,200 hours (57,951 kWh/48.31 kW) and 3,702 hours (130,702 kWh/35.31 kW), respectively; however, it is unclear if the HVAC fans are modeled as cycling to meet the cooling and heating loads of the building during unoccupied hours. Table G3.1.4 in the Proposed building column requires that HVAC fans that provide ventilation air in the Proposed model must be modeled as operating continuously during occupied hours and cycled to meet the cooling and heating loads of the building during unoccupied hours, unless one of the exceptions of Table G3.1.4 are met. In addition, Section G3.1.2.4 requires that supply and return fans reflected in the Baseline model must be modeled as operating continuously during occupied hours and cycled to meet the cooling and heating loads of the building during unoccupied hours,
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