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CI-v4 EAc2:Optimize energy performance

Lab with 100% OA (No Recirculation)

Hi All,

Hope you all are safe.

I am doing energy model for laboratory building registered under LEED ID+C v4. In this building, 80% of areas are designed with laboratory spaces & 20% of spaces are office areas such as cabins, meeting room, waiting lobby, reception etc.

I need your guidance to create the baseline energy model and proposed design energy model.

The proposed HVAC design is as follows,

Chilled water is supplied from District Cooling Plant to AHU’s (3 Numbers). 100% OA is served as supply air by these AHU’s to all the conditioned areas (No recirculation & No separate fresh air provided).  In addition, exhaust fans also proposed separately to maintain the required ACH.

Energy Model software capability,

In our software, both supply air flow rate & fresh airflow rate should be provided separately.

Here, the supply air is as known as conditioned air used to cool the spaces & Fresh air is considered as just outdoor air without conditioning.

In this case,

  1. how we can model the above-mentioned HVAC design in Base case & proposed case?
  2. Also, how to match the flow rates shown in IAQ Calculator

 

Just FYI,

As we know that, outdoor air will be delivered by FAHU & conditioned and treated by outdoor units such VRF, Condensing Units, etc... However, in our software this facility is not available (supply air only can be modelled).

 

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Fri, 11/06/2020 - 14:40

The Proposed case always gets modeled consistent with the design. It is unusual that your software would require you to model the supply airflow separately from the outdoor air. Most simulation programs can model a single 100% OA system as you have described for your design. The Baseline would be modeled with the appropriate system from Appendix G with chilled water cooling. Exception c to G3.1.1 and the exception to G3.1.3.13 will likely apply to the laboratory spaces. The Baseline outdoor air should be modeled as the minimum code requirement, and the Baseline supply airflow should be modeled according to G3.1.2.9 (note the exception to G3.1.2.9.1 for laboratory spaces). You can choose to apply Addendum cn to force the Baseline laboratory systems to be 100% OA, and Addendum c to model the lab exhaust fan as constant horsepower.

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