OpenStudio Tips - Warning GetOAControllerInputs

We discuss the warning ** Warning ** GetOAControllerInputs: Controller:MechanicalVentilation="CONTROLLER MECHANICAL VENTILATION ... Cannot locate a matching DesignSpecification:ZoneAirDistribution object, what it means, and how to resolve it. Transcript: Hello all. We are back here with another episode. Real quick tip. This is a very common warning. It says "GetOAControllerInputs: Controller:MechanicalVentilation="CONTROLLER MECHANICAL VENTILATION". It says it cannot locate a matching DesignSpecification:ZoneAirDistribution object for your Thermal Zone. It goes on to say that it cannot find that so it is going to use "default zone air distribution effectiveness of 1.0 for heating and cooling". This is a this is a common error. It is not a big deal. You can ignore it, but it depends on what your zone air distribution effectiveness is. For example, if you have Supply Air from the ceiling level or Supply air from the floor level. And also where your return air is coming from. This comes from ASHRAE 62.1; the ventilation rate procedure. We can take a look at that real quick. You could go to any one of the mechanical codes and find the ventilation part of the code; which is based on the ASHRAE 62.1. Mechanical Ventilation...outdoor air required...we can scroll down to the Zone Air Distribution Effectiveness. If you have ceiling or floor supplies of cool air, your effectiveness is 1.0. Ceiling or floor supplies of warm air with a low return the effectiveness is 1.0. If you are supplying warm air from the ceiling, and you also have a a return on the ceiling, then your distribution effectiveness is 0.8. That is what these numbers are. We can go to OpenStudio...this is the crux of the matter. We have an outside air controller that is trying to figure out how much outside air is required. If we go to the Thermal Zones Tab...Cooling Sizing Parameters...we have this column right here: Design Zone Air Distribution Effectiveness in Cooling Mode. If you have not edited these, by default these will be a blank in your OpenStudio file. When it gets translated to EnergyPlus, EnergyPlus does not know what to do. It just automatically assigns a number 1.0 to that value. But, it is good practice to go through here and ensure that you do have the correct Zone Air Distribution Effectiveness for the type of system you are modeling. If you want to get rid of that error; is type a 1.0 in here and then select all and apply to selected. Likewise, for the Heating Sizing Parameters tab, we can do the same thing. Let us just assume that we have a ceiling supply diffuser and a ceiling return grille. This is the Heating Sizing Parameters tab, so we will select all and apply to selected. Give it a second... We can click over to Cooling Sizing Parameters, click back to Heating, and double check that was applied...yes, it was. We can go to run the model. The model was run successfully. We can go take a look at our eplusout.err file. We will reload it. We can see that that error was resolved. Thank you! Please like and subscribe! ... Complete transcript: https: //www.helix-engineers.net/technical-articles