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Ideal Loads and Economizer set up [closed]

asked 2016-04-27 03:59:45 -0500

FSilenzi gravatar image

updated 2017-10-18 07:20:27 -0500

I need to run simulations in which the cooling and heating loads are supplied via Ideal Loads. I have opened another question here which I have followed, but working on the model have brought other questions to my mind. I have used the "ideal loads" option to model the air conditioning system, setting the ACH as indicated to me in the previous question, the simulation ran and I compared these variables:

-Zone Ideal Loads Zone Sensible Cooling Rate

-Zone Ideal Loads Supply Air Sensible Cooling Rate

which are exactly equal. As far as I know, there should be a difference between the two variables if the system is supplying unconditioned outdoor air whenever the outdoor air temperature is suitable in order to save energy.

I am then asking you, how can I understand if the OA is supplied (using OpenStudio) and what option/parameters shall I check in order to model the system correctly?


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Closed for the following reason question is not relevant or outdated by FSilenzi
close date 2016-06-10 02:42:13.545516

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answered 2016-04-27 10:36:35 -0500

Adam Hilton gravatar image

Like for the ...Supply Air... and the ...Zone... output variables there are also a set of ...Outdoor Air... output variables for the ideal air loads system. You can use that to check the energy/rates for outdoor air.

OS leaves all the parameters in the IdealLoadsAirSystem object to defaults, and I don't believe you can change anything in the GUI, so you'll have to write a measure. The default for the outdoor air parameter is to not have any outdoor air which would explain the lack of difference you're seeing.

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Thanks @adhilton If such a measure would exist I shall find it on the BCL right? Or is there another repository/library which I can check?

FSilenzi gravatar image FSilenzi  ( 2016-04-28 01:42:07 -0500 )edit

I managed to input the correct objects for Ideal Loads in E+ idf editor, and the simulation seems to run seamlessly. I have temperature match as well as hourly air changes satisfy the requirements. What still confuses me is how can I check if the enconomizer is working, because I have Zone Ideal Loads Economizer Active Time as output, as well as Zone Ideal Loads Supply Air Sensible Heating Rate (a) and Zone Ideal Loads Zone Sensible Heating Rate (b). I have a different from b even if the economizer has 0 hours of functioning. Why this could happen?

FSilenzi gravatar image FSilenzi  ( 2016-05-02 03:07:43 -0500 )edit

You could have a heating limit set or a specified minimum of outdoor air being brought in. Other than that, not really sure.

Adam Hilton gravatar image Adam Hilton  ( 2016-05-02 08:40:51 -0500 )edit

ZoneHVACIdealLoadAirSystem has "heating limit" set to "no limit". The only limits I have set are for cooling because I could not turn on the economizer without setting "cooling limit" as "limit flow rate" and the "maximum cooling rate flow rate" set to autosize.

FSilenzi gravatar image FSilenzi  ( 2016-05-02 09:45:31 -0500 )edit


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Asked: 2016-04-27 03:59:45 -0500

Seen: 190 times

Last updated: Apr 27 '16