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Overview of BEM softwares that are more detailed than EnergyPlus

asked 2019-11-27 14:15:02 -0500

mldichter's avatar

updated 2019-11-30 13:01:40 -0500

As of late, I've been assigned to projects that EnergyPlus is not well suited to. Things like modeling thermal losses and leakage from ducts in attics, the affect of envelope and duct sealing on the flow through vertical ducting at different heights, and controlling equipment in EnergyPlus to exactly matched high frequency logged data, like which speed an AC runs at and for how long and when.

I've found workarounds and kluges for all these problems using EMS and inappropriate use of certain objects, but they are time consuming to design, implement, and validate in EnergyPlus and must be redone for each building model.

I'm considering taking the time investment to learn another building energy modeling software for these projects that require detailed geometry, control logic, and experimental equipment which EnergyPlus isn't designed to simulate. I will still be using EnergyPlus for models that involve average or generic buildings and equipment, but it's clear that EnergyPlus is not a one size fits all for future projects.

ESP-r looks like the best candidate for very detailed simulation, but I don't know how easy changing control logic for equipment is.
Modelica is made for controlling equipment, but I don't think it does any building simulation like lighting or heat flux through surfaces.
The Building Controls Virtual Test Bed can couple different software together, like using Modelica to control equipment in EnergyPlus.

What are people's thoughts on these? Whether or not a software is currently maintained is extremely important, which is a huge plus for EnergyPlus. I don't want to learn ESP-r only to find out it isn't maintained. MODELING OF PRESSURE would be super nice too, which is not in EnergyPlus.

A future software worth mentioning is the next generation of EnergyPlus, Spawn-of-EnergyPlus (Spawn). But will Spawn have the same limitations as EnergyPlus in terms of very detailed modeling like the three projects I mentioned in the first paragraph? In other words, will spawn being able to specify specific equipment, specific controls, specific geometry, and specific physical components tying everything together in the model, like ducts?

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@MatthewSteen The spawn, or possibly soep, tag was in reference to the next generation of EnergyPlus. A development version is currently available. What tag should I use?

mldichter's avatar mldichter  ( 2019-11-27 20:37:41 -0500 )edit

I know. For now I think energyplus and modelica could suffice.

MatthewSteen's avatar MatthewSteen  ( 2019-11-30 12:28:56 -0500 )edit

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answered 2019-11-27 18:44:06 -0500

You should be able to use the Modelica Buildings Library ( for this purpose. It has a room model that has been used for dynamic multi-zone heat transfer in buildings with a few zones, but it has no graphical geometry editor, you will need to enter the surface areas and orientation in a text editor ( This model has no daylighting simulation, but you could read in a time schedule that you compute with a lighting simulation software. Controls, pressure in duct networks and the resulting flow distribution is computed in Modelica.

If you are willing to setup and try research code on Linux, which is still in active development and debugging, you could directly couple Modelica HVAC and control from the Buildings Library to the EnergyPlus envelop model, see

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@Michael Wetter Thank you for the Modelica link. I might end up using it. I'm surprised you didn't say anything about BCVTB as you're one of the contacts for that software. Do you recommend Modelica over BCVTB for the three examples I mentioned? And you might be just the person to ask about ESP-r too since BCVTB is compatible. Can ESP-r do the example projects, or would I just have another piece of software that I'd have to come up with a clever way to model ducts, pressure, or precisely control equipment?

mldichter's avatar mldichter  ( 2019-11-27 20:52:18 -0500 )edit

@mldichter: I think a direct coupling using Spawn, or the FMI export of EnergyPlus ( is going to be more streamlined to use than the BCVTB for your purpose, as it avoids using a middleware that you would need just for the coupling. I don't know enough about the ESP-r HVAC and control capabilities to judge its suitability for your purpose.

Michael Wetter's avatar Michael Wetter  ( 2019-11-28 07:44:47 -0500 )edit

@Michael Wetter I managed to find a Modelling Air Duct Leakage but the duct wasn't modeled in an attic, or anything as far as I could tell. Modeling duct leaks looks possible in ESP-r since a lot of simulation behavior is user specified, but a lot of work. Modelica is looking more and more attractive. We don't do a lot of lighting controls, so daylighting missing from Modelica isn't a bit deal.

mldichter's avatar mldichter  ( 2019-11-28 14:39:58 -0500 )edit

@Michael Wetter I looked a bit through Modelica and couldn't find easy to specify modeling of ducts. Do you know of anything like that in Modelica? Otherwise, looks like using EnergyPlus EMS will work just as well as specifying behavior in Modelica. The current plan is to make a register in EnergyPlus that will simulate the leaks, a tiny conditioned zone in the attic representing the duct for thermal conduction to the attic, and EMS to control it all. We have a duct model that we can use to generate a lookup table. Do you know of a better solution?

mldichter's avatar mldichter  ( 2019-11-28 15:12:06 -0500 )edit

answered 2021-11-01 11:30:35 -0500

AGeissler's avatar

FWIW, ESP-r is maintained. I.e., there is a new version approx. twice a year and basically one can reach out to ESRU.

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Asked: 2019-11-27 14:15:02 -0500

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Last updated: Nov 27 '19