Lesson summary: This transcript covers practical DOE 2.3, eQUEST, Dedicated Outdoor Air Systems, Energy Recovery Ventilation workflows for eQUEST energy modeling. The transcript has been organized with SEO-friendly headings and readable paragraph breaks so it can be posted with the corresponding training video.
With the addition of DOAS, it would follow that we can model energy recovery with the dedicated outside air system. But if you look in the help file, it will say that you cannot add ERV to a DOAS system. On the other hand, the release notes for 7175 say that ERV was added to DOAS and it's unclear. So right here, we're going to show you how to model it and then how to verify what we modeled is actually operating the way that we think it should.
And if there's any changes that we need to modify to make that work. We can add an enthalpy wheel, counter flow, operating on the default and actually run an ERV unit. Again, we can define the design air flows because these can be different depending on where the air is coming from. If the air is coming from an exhaust stream and a supply stream within the same thing, the airflow is going to be very similar, but that's not always the case.
So we can define those here and then also all of the effectiveness just like we had in previous versions of eQUEST. However, this applies directly to the dedicated outdoor air unit and never before has this worked like this because this will automatically take the heat that's picked up from the zone and bring it back through. In prior versions of eQUEST, that was just an impossibility without doing some very intense work arounds. It terminated to airs, view the output file.
And here in my haste to include ERVs with the dedicated outdoor air systems, I forgot to look at one of the inputs for this and now we have to troubleshoot using the air message. Energy recovery ventilator DOAS1NNW uses the HVAC fans but recovers zonal exhaust air. The ERV must have self-contained fans in this configuration. So in our haste here, we forgot to also set the ERV fans to self-contained.
In order to do that, we have to go to the DOAS unit, outdoor air, and we set up heat recovery one under the second heat recovery tab. We have to go to ERV fans. They typically use the HVAC fans. In this case, we have to select them to self-contained and we have to set up the exhaust fan power and we have to set up the makeup air fan power.
If indeed this does use the fans from the dedicated outdoor air system to power this, what you'd have to do is just simply enter a really small number so that the fan power is already accounted for in the DOAS unit. So we could just go 0.001 or something like that, or 0.002 I have. We can also specify the KW per CFM which is going to be much, much less. If indeed the ERV had its own fans, we could enter a few more fields here which we're not going to do because we're assuming the fans are 0.
But we can also set up the fan power curve here. Right now we'll just assume the default fan power curve because it doesn't matter when the fan is 0. And we don't want to bore you creating a variable speed fan curve, especially because that's done in another eQUEST course. In any case, we are still assuming that the fan power from the ERV still comes from the DOAS units.
These fans are variable speed. I have to change the other unit as well. Yes, heat recovery 2. And I'm actually going to just leave the fan power blank in this case.
What's neat, you can see the DOAS options here. We can also see the other system diagrams. We can see the energy recovery unit here. But as that stands, there's nothing that really shows the dedicated outdoor air system interacting with the regular air handling units.
And now we can simulate. You can see when we go directly to the sim file, we no longer have any fatal errors. However, there are some less extreme notices that we have some some convergence issues. But we left this very poorly defined just to set up the model.
So I would anticipate some errors. I was curious to what they would be. I had run this ahead of time, of course, and saw that we had convergence errors.
This lesson provides practical guidance for modelers working with DOE 2.3, eQUEST, Dedicated Outdoor Air Systems. Use this organized transcript as a reference while watching the video and applying the workflow inside eQUEST.