Natural Ventilation Only

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Hi,

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

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Bruce Easterbrook's picture
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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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Christine,

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 http://www.bfrl.nist.gov/IAQanalysis/. 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 http://apps1.eere.energy.gov/buildings/energyplus/. 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 http://www.bfrl.nist.gov/IAQanalysis/software/LOOPDAdesc.htm. It?s basically solving the ?inverse? problem.

Lisa

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