Modeling Energy Recovery Only at System Level with Trace 3D

I'm trying to keep this simple, but as an engineer, have a habit of over complicating things. Please comment below if you have ideas on how to get impact of ERV on your system in Trace3D done in an easier way!

We do a lot of adaptive reuse historic renovation projects where the developers only have the budget for constant volume split DX systems. The loads are highly unstable due to the large areas of historic glazing, infiltration issues, and negatively pressurized building from "value engineering" requests.

Most developers prefer to exhaust bathroom, kitchen, and laundry air as near as possible; often side wall. The outside air, when required, is simiply a duct extending to a side wall 10' away from the unit exhaust. There is aboslutely no hope in controlling building pressure under these conditions. Combine that with old, leaky historic buildings, and....well you if you're reading this you know what that means.

So we have a project recently where I want to demonstrate the benefit of at least pre-treating the air with and ERV. We'll give some latent capacity to the constant volume split heat pumps inside while properly ventilating the tenant space and pressurizing the building.

Doesn't Trace3D already have a heat exhanger you can simply add to a system that is the ERV? Yes! but under the hood, Energy Plus (the open source modeling engine used by Trace3D) uses "ideal peak" conditions to generate the reports. This can get confusing. I want my reports to show the impacts of the heat exchanger on the building in the reports.

We're going to use a DOAS to dump pre-treated ventilation air that represents the leaving air temperature from the ERV. After you've completed your building model, move into the Systems and follow these steps:

Now you're ready to assign zones and finalize your zone equipment configuration. Run the calculations and you'll see the impact of the treated air directly on the zone equipmet.

This keeps the impact of the ERV visible to the client in a measurable way so we can discuss how a simple change can lead to major gains not only for the tenants directly but for the building itself.

Full disclosure: I haven't completely evaluted this method and it is not a formally endorsed method at all. I am not familiar enough with what Energy Plus does under the hood or how Trace3D uses it. If you have any comments, suggestions, or corrections please share below! There is limited documentation about Trace3D, so I could use all the help I can get!