Honeybee Openstudio Baseline System 7 Bug

Hi,

I try to create the ASHRAE 90.1 Baseline system 7 with Honeybee openstudio. I found that the Maximum air flow rate for variable volume fan in the air loop is hard sized and the maximum air flow rate in the terminal box is hard sized as well (See images).

They should be auto sized and the hard-sized values will significantly under estimate the building energy use and cause long hours of unmet load hours.

Does any one know how to fix this issue in the honeybee ?

Thank you very much.

Replies are closed for this discussion.

Replies to This Discussion

Permalink Reply by Chris Mackey on April 20, 2016 at 4:15pm

Bao,

If you upload your GH file, I can verify the exact cause but I believe this is happening because you have set the reciurculatedAirPerArea_ on the "Set EnergyPlus Zone Loads" component to a value other than 0. By default, the "Autosize" feature on EnergyPlus/OpenStudio will only size the VAV system to deal with thermal loads and so it usually sizes the system to be too small to handle the required recirculated air for programs like hospital patient rooms. For this reason, I built in a hard-sizing capability whenever you specify a non-zero reciurculatedAirPerArea_. If you just set this recirculatedAir value to 0, you will get the default, Autosize capability like in the attached file:

-Chris

Attachments:

Correct_Sizing.gh, 496 KB

Permalink Reply by Bo Lin on April 21, 2016 at 8:15am

Hi Chris, I followed your file and re-create the OS file, the air loop fan and terminal air flow rate are still hard sized. Please see attachment.

Thank you very much

Attachments:

Correct_Sizing.gh, 578 KB
GH OS File_Autosize.osm, 220 KB

Permalink Reply by Chris Mackey on April 21, 2016 at 6:41pm

Bo,

The components in your file were old. Just update to the version on the github (as in the attached file) and you will see that you always get "autosize" unless you specify recirculated air.

-Chris

Attachments:

Correct_Sizing_CWM.gh, 538 KB

Permalink Reply by Bo Lin on April 22, 2016 at 6:54am

Hi Chris,

how much time it takes to add baseline 8 into the honeybee ? I want to do it.

Thanks

Permalink Reply by Chris Mackey on April 22, 2016 at 7:40am

Bo,

It's relatively quick once we establish all of the things that we want to change on the other VAV system templates. Still, we really need to decide on this first as we would likely have to go back and re-do the implementation of system 8 if we decide that we want to add/remove other features. I feel that, right now, there's been such a prioritizing on allowing people to size the HVAC elements in GH and not enough on adding/removing key elements to the system like heat recovery, humidity control, filters on the fan or just allowing people to set a fraction of recirculated air (recirc air only works for system 7 right now). Personally, I feel that most people are going to want the system autosized and we don't need to have component inputs for these. All of these sizing inputs really just distract users from applying the things that they really want to test and they also make a nightmare for software development (this really seems to be the major reason why the implementation of the systems is not finished yet). Rather than focusing on sizing parameters, we should focus on the key elements of the HVAC that people want to add/remove and they can always change the parameters of these elements in the OpenStudio interface.

We can discuss this more when we talk on Thursday. If you want to prepare for it, having a short list of the most important features would be helpful.

-Chris

Permalink Reply by Bo Lin on April 22, 2016 at 8:16am

Yeah, yeah !

Leland and I were discussed yesterday and we will prepare that from daylighting, mechanical side and from whole design perspective.

Looooking forward talking to you next Thursday.

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