night time ventilation strategies

miguelnery · Posts: 72

Hi Andy,

I don’t arrive to simulate night time ventilation!

• To keep it simple I’m just working on “cooling design”;
• I’ve created 2 equal files, one with day time ventilation (windows and vents), and the other with night time ventilation (windows and vents).
• For the second, I’ve created a “night vent 20:00-8:00” profile and with that a “night vent” schedule, and applied it to the windows and vents opening

Running both strategies I get exactly the same results!
What’s wrong?

Best regards

Miguel

Andy Tindale · Posts: 1149 Location: Stroud

Hi Miguel,

I can't download the files you posted because of a technical hitch, but I wouldn't expect the two cases to give different results because Cooling Design Calculations use Scheduled natural ventilation even when Calculated natural ventilation has been selected in the building model options dialog. This is new behaviour. In pre-version 1 beta test releases Cooling Design Simulations used Calculated natural ventilation when it was set.

Try running a simulation and see if you get the expected behaviour then.

Best regards
Andy

miguelnery · Posts: 72

Hi Andy,

It works, but let me tell you that is more time consuming!!!

Thank you

Miguel

Franck.Boutte · Posts: 12

Hi Andy,

I can't understand why you suppressd the calculated ventilation option in cooling design analysis. I was always working with coolong design tab during beta period and it was a very good tool to test night time ventilation and variable vnetilation rates during the day. Could you explain me the reason to have suppressed this. Could it be possible to have this funcion again in the next release ?

Franck

Andy Tindale · Posts: 1149 Location: Stroud

Hi Franck,

The main purpose of Cooling Design calculations is to size cooling equipment and to calculate internal temperatures under summertime design conditions. The reason DesignBuilder version 1 forces Scheduled natural ventilation to be used is that we considered it important that the assumptions behind the cooling design calculations could be easily documented (including natural ventilation air change rate). This is difficult with Calculated natural ventilation because of the large amount of data involved (cracks, openings, pressure coefficients etc, wind speed and direction etc).

I would welcome views from other DesignBuilder users on this - we are of course open to changing the way the software works to fit the way people want to use it.

Best regards
Andy

Andy Tindale · Posts: 1149 Location: Stroud

Franck,

I appreciate that using Cooling Design to evaluate Calculated natural ventilation is a useful feature and so we will add a new option for this. This capability will be available in a (hopefully near) future version.

Andy

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