Exceptional Calculation Method for Demand Controlled Ventilation

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Hi folks,

I am simulating a 24-floor building to be LEED certified. The software is
Equest. In order to achieve as many points as possible in EA CR1,
demand-controlled ventilation (DCV) has been modeled in the proposed design.
But we are not sure if this stragety needs Exception Calculation Method
requested by USGBC. In one of CIR historical archive of LEED online, USGBC
requested exceptional calculation method for schedule-based DCV models. I
have no idea if USGBC would treat DCV models in Equest as those of

The use or removal of DCV will decisively impact the achieveable points of
EA CR1. I am wondering if anyone in this community has clear picture on this

Thanks in advance.


Jessica XP's picture
Joined: 2011-10-02
Reputation: 0

I got a LEED submittal review last month that didn't allow modeling DCV in
eQuest without using the 'exceptional calculation method'. You can model
DCV with the keyword in eQuest, but (some) LEED reviewers want to see
savings isolated from the measure. It just ends up being a bit more
modeling/ reporting time on our end.


Aleka Pappas4's picture
Joined: 2011-10-02
Reputation: 0

Unlike the experience that Aleka Pappas described, I have never been asked
by the USGBC to provide an Exception Calculation Method when using DCV in
eQuest. This only proves that the review process is not consistent...

Regardless, I've only modeled DCV using the minimum flow control options
under the Air-side HVAC tab within the thermal zones (MIN-FLOW-CTRL). You
have the option of DCV with reset up, reset up/down, or reset down.

If you're trying to model DCV in a different way, you probably should
provide documentation for an Exceptional Calculation Method. These are not
hard to put together. On the EAc1 template, there is a specific area that
you'll need to fill in - essentially describing the method you've used and
your reasons for it along with the energy and cost savings that method is
calculating. Read the instructions on the template - they're pretty

When I've done Exceptional Calculations Methods in the past, I've created a
new proposed case model as the USGBC will want to see output from the
proposed case model with the Exceptional Calcs and without it. You'll
document Table 1.8.2 on the EAc1 template with the data reported in the
proposed case model without the Exceptional Calculation Method.

Amanda Bogner, PE LEED AP

Amanda Bogner's picture
Joined: 2011-09-30
Reputation: 0

Follow up question. I have just run a building using a DVC method and have
seen a significant savings between 20% and 30%. Does this surprise anybody?
(It surprised me, but cannot find any errors in the model). It is an all
electric building in the Northeast region. Thanks for any input.


Mike Witkowski, PE's picture
Joined: 2011-10-02
Reputation: 0