Dear Concern:-
Our Design project does not have DCV (Demand Control Ventilation ) so can we model the fresh air identically Baseline and prposed case as per ASHRAE 90.1.2010 SectionG3.1.2.6 but we receive the review comment from GBCI
Review Comment :-
G3.1.2.6 exception c) requires that the Baseline be modeled with the minimum amount required by the rating authority, which is equal to the rates determined in EQp Minimum Indoor Air Quality Performance. Note that the 30% increased ventilation, if pursued within EQc Enhanced IAQ Strategies, should not be modeled in the Baseline Case building. Based on the current information in EQp Minimum Indoor Air Quality Performance,
Now my Doubts are
1.How to model outdoor air flow identically / (Actual for Design & 62.1.2010 minimum requirement for base case)
2.If we model 30% Outdoor only in Proposed means how we get points in Cooling ??
(we provide additional fresh air for Occupant wellwish as per LEED so it must be modeled identicaly in both case )
3.In G3.1.2.6 some exception are there it is confusing a lot our project Ez is 1 or blwow 1 (0.8) in this case can we model outdoor air identically or not ??
4. G3.1.2.6 exception c. If the minimum outdoor air intake flow in the proposed design is provided in excess of the amount required by the rating authority or building official then the baseline building shall be modeled to reflect the greater of that required by the rating authority or building official and will be less than the proposed design.
the above Exception C is more confusing for Example the Space requires 100 CFM ( 77 Minimum Requirement & 23 Additioanl 30% Fresh air ) freh air due to Fan air flow availability we provide 120 CFM in this case how i model this
Option 1 - Identicaly model bothcase with 120CFM ( Fan capacity )
Option 2 - 100CFM for baseline case ( Actual Requirement with 30% Additional )& 120 for Proposed case
Option 3 - 77 CFM for baseline ( Minimum fresh air requirement as per ASHRAE 62.1 ) & 120 CFM for Proposed Case
Mankisha Veng Veng
March 19, 2022 - 12:24 am
awaiting for the reply
S S
March 21, 2022 - 8:16 am
My opinion is that option C is the correct choice.
Over the course of a year, increased outside air will undoubtedly result in increased energy consumption by the HVAC system, as the heating and cooling loads to condition it will increase (Q=m*C*dT). Measures like heat recovery wheels, efficient fan systems, and variable air volume can help save energy in HVAC systems.
Cory Duggin
Senior Energy WizardTLC Engineering Solutions
53 thumbs up
March 21, 2022 - 12:17 pm
In LEED v4 you only model the OA the same in the baseline and proposed if they are both using the ASHRAE 62.1 minimum flow. If you are supplying 30% more OA to get better IAQ and go for the Enhanced IAQ credit, you have to take an energy penalty, so the baseline will be the ASHRAE 62.1 minimum flow and your proposed will be ASHRAE 62.1 min+30%.