What is the best energy modeling workflow when starting with Revit?

asked 2019-01-26 19:21:18 -0500

RM Lex
31 ●1 ●3

updated 2019-01-27 09:42:24 -0500

Hello to all of the members on here. I just joined, because I have been searching the internet for information on energy modeling programs to use with Revit. I am currently an architect, but also formerly an electrical engineer with an MEP firm, and I am basically starting from the ground floor when it comes to energy modeling - at my MEP firm, the mechanical engineers did what little energy modeling we performed.

My firm designs all projects using Revit. I have been looking for the best way to take this geometry, starting in the SD phase, and run energy simulations. I'll mostly be using this to evaluate the effectiveness of building envelope components and orientation, though I also intend to carry the energy model through the design process so that I can verify actual building usage against my model after construction.

I've looked into a number of programs, starting with Revit's integrated software, Insight. Although I may be doing something wrong, Insight seems to be very conceptual - simply slider bars indicating potential savings from changing the entire building average R-value, for instance. I'm looking for something where I can break down energy use room by room, and see where shading can be most effective, or other targeted solutions. I have downloaded EQuest, but it seems to only accept imported 2d CAD geometry, not 3d. Trane Trace looks pretty powerful, but I don't really have thousands of dollars to spend. The other program that I have tried is Open Studio, which seems promising. However, it does not accept gbxml files from Revit as well as it does files generated directly in sketchup. In the project that I am starting on, I have dozens of surfaces generated in rooms that should be fairly simple.

Does anybody have any thoughts on the best program/workflow? I know it's an open ended question, but any advice would be appreciated. Also, if you know of any good training materials, or online college classes, for the best program, or for energy modeling in general, it would be very helpful. I've asked a couple former colleagues and current MEP consultants, but they are mostly using Trace energy modeling for the bare minimum required on occasional LEED projects, and didn't have much in the way of guidance. I'm very interested in sustainability, and in design verification, but I don't really know where to start.

Thanks, Ryan

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"I'll mostly be using this to evaluate the effectiveness of building envelope components and orientation, though I also intend to carry the energy model through the design process so that I can verify actual building usage against my model after construction."

While it is convenient to not have to remake inputs and geometry for the design process, often the questions are very different. In early design you want simple, even single-zone models to do lots of quick parametric studies. Later design is for loads, LEED, compliance. Use the appropriate detail for the question/goal.

mdahlhausen ( 2019-01-30 16:31:22 -0500 )edit

Using materials-based thermal properties for energy analysis in Revit makes a world of difference. I encourage mechanical engineers to demand architects add this to their agreements.

ThinkRevit ( 2019-10-19 08:48:34 -0500 )edit

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answered 2019-01-30 15:44:37 -0500

saeranv
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updated 2019-01-31 09:57:04 -0500

Ryan,

I work at an architecture firm doing exactly the kind of energy modeling work you're describing (from early conceptual studies all the way to mechanical systems implementation in design development).

For my energy modeling, I use Honeybee from Ladybug: https://www.ladybug.tools/. Honeybee uses OpenStudio for energy modeling, Radiance for daylighting/glare, and numerous bespoke python scripts for additional thermal comfort, environmental analysis (i.e EPW visualization, urban heat island modeling), and even CFD simulation (via OpenFOAM). In my opinion it's ecosystem of analysis is unmatched (disclosure, I am biased, as I contribute to the code). Also it has a good forum that will debug, and answer any questions quickly: https://discourse.ladybug.tools/.

Right now the legacy version of Honeybee (which contains it's energy modeling workflow) is only available for Grasshopper. However, a version supporting Dynamo is in the works.

In the meantime, I have a custom workflow where I use Revit to generate a simple, bare bones OpenStudio model of thermal zones/spaces from Revit area plans, and then I open the OpenStudio model in Honeybee, and do all additional BEM modeling in Grasshopper with Honeybee. Unfortunately this is based on a Revit plugin we're developing at my company that isn't ready to be released. However, I believe this kind of workflow can be reproduced using the gbXML export tools in Revit and gbXML import tools in Honeybee.

So I would recommend using Grasshopper via Honeybee to use Openstudio, rather then Sketch up. Not only because you can use Honeybee and all it's associated tools, but also because Grasshopper is a much more sophisticated geometry modeler then sketchup.

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I found Ladybug a couple days ago, and it seems like the perfect tool for SD level. I only have limited experience with Dynamo, and none specifically with Grasshopper, but it may be worthwhile learning if only to access the immediate feedback with Ladybug/Honeybee. This is exactly what I'm looking for. I'll have to play around with these tools to fully understand the workflow, but is there any reason to go into the OpenStudio environment at all, or can everything be run directly out of Honeybee?

Thanks, Ryan

RM Lex ( 2019-01-30 17:26:43 -0500 )edit

You can modify quite a lot of OpenStudio parameters through Honeybee, and for SD level development I've never needed to go into the OpenStudio app.

I tend to use the OpenStudio app to assign measures, to modify/create HVAC systems, when checking default parameters, and to use the DView results viewer. Technically, you can add measures through Honeybee, and there is a new addition to Honeybee for modeling detailed HVAC systems (https://discourse.ladybug.tools/t/iro...) so these are all motivated mainly by personal preference.

saeranv ( 2019-01-30 18:20:52 -0500 )edit

I would reccomend checking out HB's repository of example scripts to get started: http://hydrashare.github.io/hydra/

Here's a simple one to construct, post-process and view an energy balance: http://hydrashare.github.io/hydra/vie...

saeranv ( 2019-01-30 18:23:51 -0500 )edit

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answered 2019-01-28 08:30:07 -0500

JKavanaugh
86 ●1 ●5

Hi Ryan,

I'm an ME working for an MEP firm and I handle pretty much all of the energy modelling we do. I have a few thoughts I can share with you.

I've considered using Revit for energy modelling because most of the projects we get from architectural firms are already in Revit. I spent a little bit of time trying to work in existing Revit models, and I quickly realized that the amount of time I would spend setting up spaces within the existing model would be much greater than building the energy model from the ground up using Openstudio/Sketchup. However, it may be possible to make the energy model process quicker if you are building the Revit model in house. I also found the capabilities to be very conceptual: it didn't seem to have a whole lot of flexibility for different types of analyses.

I have the same thoughts as you on Trane 3D Plus (too expensive), but I played with their 30 day demo for a bit and found that it doesn't have as much flexibility for mechanical systems as Openstudio does. I will say that the geometry creation is a little more intuitive and more forgiving when it comes to making mistakes and backtracking than the Openstudio Sketchup plugin. Both software packages use Energy Plus as the engine, but I think Openstudio is able to access more objects. There's also a lot more technical help available for Openstudio than for the Trane software.

Openstudio probably has a steeper learning curve than some of the other options, but after using it consistently for about a year and a half now, I've reduced the time I spend modelling a single building for code compliance (which requires a baseline and proposed model) from 10-15 days to about 3-5 days. I took a 3-day training course for the software which has been worth every penny.

Sorry I can't offer you more advice about the specifics of Revit, but I hope you found this helpful anyway.

-Josh

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Josh,

Thanks for getting back to me. My intention is to do multiple iterations of the energy model, to help me design an efficient building envelope before the MEP engineers even touch it. I hope to do as little re-modeling in a different program as possible. If I can find an unused Sketchup Pro license at my firm, I'll look into bringing the Revit file into Sketchup for some quick model cleanup; that may help. If you don't mind my asking, what was the training course you took? I'd be interested in anything that shortens my learning curve significantly.

Thanks, Ryan

RM Lex ( 2019-01-28 17:13:04 -0500 )edit

Ryan,

Openstudio has a lot of capability to do what your talking about. You can quickly change R values for walls and roofs to see relative changes in energy use using measures. A separate software called Parametric Analysis Tool (PAT) comes with Openstudio and is designed to do just that.

I've used the Sketchup Pro demo to bring in CAD and other formats into Sketchup to make the model geometry, but that's usually more pain than it's worth. I find it easiest just to bring in an imagefile of the floor plan and sketch over that to build the geometry, then scale it to the correct size.

-Josh

JKavanaugh ( 2019-01-28 17:28:17 -0500 )edit

As for the training course, it was a program offered by the local electric utility. It was intended to get commercial clients to sign up for a demand reduction scheme that required energy modelling with Openstudio. We've never done the demand program for any of our clients, but it was worth it just to learn the Openstudio software.

JKavanaugh ( 2019-01-28 17:29:45 -0500 )edit

Thanks for all of the input, Josh. I think I'm going to try a couple of different methods of importing directly from Revit into Openstudio, and look into Ladybug and Honeybee as Saeranv above suggested. It seems like it will be a steep learning curve, but hopefully I can use these to make some better informed design decisions in the near future.

RM Lex ( 2019-01-30 17:33:13 -0500 )edit

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