Natural Ventilation Only

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I wanted to create a model in eQuest that only had natural ventilation using the S-G method and no mechanical system. Is this possible?

I have come up with the following problems:

? I have used a PSZ unit and have 0 cooling capacity, no ventilation requirements and not installed heating ? however I am still getting cooling and fan energy

? If I turn off the fans then the unmet load hours are not calculated as they depend on when the fans are scheduled

? If I use a heating only system, natural ventilation inputs are not allowed

? I don?t want to just use an economizer for natural ventilation as I want the outside air to be dependent on the wind speeds and not forced with fans.

Any thoughts?

Christie Rimes, LEED BD+C

Rimes, Christie's picture
Joined: 2011-09-30
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Bruce Easterbrook's picture
Joined: 2011-09-30
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Another method wd be to manipulate the infiltration values which are based on building pressure differentials ie wind affected.

Thank you, Sincerely,

Michael J. McArdle , P.E.

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Joined: 2011-09-30
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What result are you looking for with the natural ventilation ? air change rates, sizing of openings?

If you want air change rates, CONTAM is an airflow simulation tool available at no charge from NIST It performs a multizone analysis of airflow, i.e., each zone is ?well-mixed? and has one temperature, airflow rate, etc. Currently, temperatures are scheduled inputs. If you want indoor temperatures to be calculated/updated as a result of natural ventilation, EnergyPlus is available at no charge from DOE There is an ?Airflow Network? capability that does almost the same things as CONTAM (use the ?MultizoneWithoutDistribution? option). The Airflow Network capability in EnergyPlus is implemented by a text file whereas CONTAM has a GUI. CONTAM can output building air change rates for every time step. I believe EnergyPlus can output an average air change rate for each zone. To get air change rate for each time, I believe you?d have to calculate it based on available outputs.

If you want to size openings, NIST has another tool, LoopDA also available at no charge It?s basically solving the ?inverse? problem.


Ng, Lisa's picture
Joined: 2011-09-30
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