I'm quite confused about airwall in energyplus

hello everyone, nowadays I’m studying how to build complex building and simulate its energy consuming. But I got some difficult about the air wall. I used to think its equal to air and its just show as a surface to make a brep closed.but today I got a little test and the result is different. so maybe I got the wrong opinion with the air wall?airwall test.gh (120.4 KB)

@witty ,

You can think of air walls in legacy as a perforated sheet of plywood. Air can flow easily though them but they block all radiant exchange. In the new LBT plugin, they are a whole new type of object that allows radiant exchange across them. This text that’s copy/pasted from the LBT Plugin Release Noes includes more detail:

True AirBoundaries

Throughout the development of Legacy, EnergyPlus had no way to specify true AirBoundary surfaces between Zones and, for this reason, legacy air walls were more like a sheet of plywood across which air could mix but sun and radiant heat could not pass. All of this changed with EnergyPlus 9.3, which introduced the Construction:AirBondary and we are happy to say that HB-Energy fully supports these AirBoundary constructions.

Now, in HB-Energy, you can simulate two rooms connected by an AirBoundary and know that the sun can pass from one to another and that surfaces can radiate heat to one another across the boundary. This will end up being particularly helpful in improving the accuracy of microclimate maps (currently under development) but it also has a range of immediately-usable applications. For example, you can now model a large indoor space like an atrium or a gymnasium as several rooms joined by air boundaries and this will help account for the differences in air temperature throughout the space without compromising the accuracy of the radiant calculation.

This section of this video also helps explain the difference:


thank you chirs, I think I got the meaning :grinning:

I saw this video the other day, and really appreciate all the work that went into Ladybug Tools, its future looks even more promising.

You demo the Rhino plugin a bit, is there any possible ETA on it that you could share? I would be curious to try it already.:slight_smile:

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@furtonb ,
We’ll start beta testing the Rhino plugin within the next couple of months with an official release soon after that. We’ll keep you in mind if you want to be a part of the beta testing group.

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Awesome, please definitely keep me in mind!

@chris there are 2 other fields under Construction:AirBoundary, Field: Solar and Daylighting Method and Field: Radiant Exchange Method. According to the Energyplus Reference Book, the both should use GroupedZones. But I can not find those two keyword in the idf file that generated by LBT, but you pointed out that in HB-Energy the wall behind Air Wall get daylight and Radiant. Does it mean, Energyplus use GroupedZones as the default method for those two fields?