# Ventilation bug about the overwrite the default value as zero

**URL:** <https://discourse.ladybug.tools/t/ventilation-bug-about-the-overwrite-the-default-value-as-zero/18948>\
**Category:** uncategorized\
**Created:** [July 13, 2022, 2:05am UTC](https://discourse.ladybug.tools/t/ventilation-bug-about-the-overwrite-the-default-value-as-zero/18948 "2022-07-13T02:05:40Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![minggangyin](https://discourse.ladybug.tools/user_avatar/discourse.ladybug.tools/minggangyin/32/216_2.png) [@minggangyin](https://discourse.ladybug.tools/u/minggangyin)\
**Post date:** [July 13, 2022, 2:05am UTC](https://discourse.ladybug.tools/t/ventilation-bug-about-the-overwrite-the-default-value-as-zero/18948/1 "2022-07-13T02:05:40Z")

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I used the shoe box annual load example for the simulation. I set infilration and ventilation as zero.

 ![image](https://discourse.ladybug.tools/uploads/default/original/3X/d/6/d6234701c936e76e3e6a61464c04ad6be7df240b.png)

But after runnning the simulation and reading SQL file, it showed mechanical ventilation energy. It is a little strange.

 ![image](https://discourse.ladybug.tools/uploads/default/original/3X/9/7/97288ccfba86ddb925637c8278734cf76ed35d30.png)

So I checked energyplus idf file which showed mechanical ventilation is zero.

 ![image](https://discourse.ladybug.tools/uploads/default/original/3X/0/3/036f979527c6093c302d113b245d4cef5526abde.png)  
 ![image](https://discourse.ladybug.tools/uploads/default/original/3X/2/5/25bb85c1c1d1a2c1f46a511b2da3bad0730f81cf.png)  
 ![image](https://discourse.ladybug.tools/uploads/default/original/3X/1/f/1f9f5a549ac4e6514db5d07e8835fd90b37e9c62.png)

Anyone can answer me which step goes wrong?

[shoe\_box\_annual\_loads-ventilation zero.gh](https://discourse.ladybug.tools/uploads/short-url/hG8NgCz5h4OMMtST22oVR8fLq9g.gh) (88.3 KB)  
[in.idf](https://discourse.ladybug.tools/uploads/short-url/cEvZ9q5bkWufsvoSOzft4qNcNQI.idf) (124.6 KB)  
[eplustbl.htm](https://discourse.ladybug.tools/uploads/short-url/qXexwVWwn9GOiQUOjlxTu1KpxpI.htm) (376.8 KB)

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**Author:** ![chris](https://discourse.ladybug.tools/user_avatar/discourse.ladybug.tools/chris/32/10179_2.png) [@chris](https://discourse.ladybug.tools/u/chris)\
**Post date:** [July 13, 2022, 5:11pm UTC](https://discourse.ladybug.tools/t/ventilation-bug-about-the-overwrite-the-default-value-as-zero/18948/2 "2022-07-13T17:11:06Z")

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Hey @minggangyin ,

What you are seeing there is the “free cooling” that you get from the air side economizer that comes with the default Ideal Air system. If you use the [HB Ideal Air](https://docs.ladybug.tools/hb-energy-primer/components/4_hvac/idealair) component to specify “NoEconomizer” on this ideal air system, you will see that you get the result that you were expecting:

 ![image](https://discourse.ladybug.tools/uploads/default/original/3X/e/a/ea02134368f68773d82a4f3e3555a510e06036d1.png)  
 ![image](https://discourse.ladybug.tools/uploads/default/original/3X/e/3/e3da31feac8bac7de1311620ddd3fdb814ec03f8.png)

[shoe\_box\_annual\_loads-ventilation zero\_CWM.gh](https://discourse.ladybug.tools/uploads/short-url/gO5ynU2FyAFZpcNsVjQNXpMuk1H.gh) (70.8 KB)

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<div class="post-metadata">

**Author:** ![minggangyin](https://discourse.ladybug.tools/user_avatar/discourse.ladybug.tools/minggangyin/32/216_2.png) [@minggangyin](https://discourse.ladybug.tools/u/minggangyin)\
**Post date:** [July 14, 2022, 1:37am UTC](https://discourse.ladybug.tools/t/ventilation-bug-about-the-overwrite-the-default-value-as-zero/18948/3 "2022-07-14T01:37:49Z")

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Hi @chris It is great! It helped me a lot .Thanks for your kindly and detailed answer!!!