Here’s an interesting conversation we had with someone on our recently. Of course, it does not reflect the views of Energy-models.com, but it does reflect the views of many engineers we've talked to about the design process and architects.

Anonymous: Hey - are you going to offer a Revit MEP training?

Support:  We would like to, but need to define the scope - perhaps you could help? Do you have any ideas on what a typical MEP engineer would want to learn to do in Revit MEP?

Anonymous: With regard to Energy Modeling or in BIM modeling?

Support: Considering we are an energy modeling website, let’s say energy-modeling, but I suppose BIM should tie into that as well.

Anonymous:  Well first thing I have to say is It’s an integrated design process in a virtual world….shit in yields shit out. Seriously, each discipline is at the bottom of the pyramid equally, so the basis of reaching the peak (LEED Plaque) is supported at the base of the design process by everyone. I’ve seen architects build crappy models to which there is 2,000+ walls in a corridor.

The basic Revit information needed for modeling starts with the Architects and how they build their rooms and components. Exterior wall banding (different color brick or materials used) breaks up walls into several different walls per room. Ideally, they should enter a single wall with an overal U-value for each wall type, but also be educated on how to do this through ASHRAE 90.1 for wall assembly U-values and also include lifetime degradation of insulating U-value (it’s a lot to ask)

The worst offenses I’ve seen is in the window assemblies.

Here’s a little story I typically run into: You have some architects that are just trying to get a job done in the quickest way possible and slap some windows into their revit model. I ask the architect for the window u-assembly value and SHGC. I get a cutsheet of what they are using in their Revit model. They use the center of glass data given in the cutsheet. This is not the same as the assembly U-value and should not be entered into any energy modeling software!!! So I ask for their Spec on the Window Assembly, and find that the center of glass U-value shows the maximum code required value and is better than the cutsheet values they provided me. So at that time I ask how they expect to get the Champagne on a beer budget. They tell me that is all they can do, or the project costs is too high and we’re back at the drafting tables trying to make it work. With that I enter in the specified Window Assembly Performance U-Value and SHGC’s into a spreadsheet which is what I would’ve done in the first place but now thanks to the efficiency of the Revit model (sarcasm), I wasted a day of my time. So again, you have to consider what you want to allow others to enter into the Revit BIM model versus you having control over it. Arbitrary data makes you want to drink beer during energy modeling.

From what I recall, the room areas, walls, etc. and including the HVAC systems/Zones are also set in Revit, but I’ve not been able to rely on that information being exported to GBXML and imported with accuracy. Again the number of walls, and reliability of room area (sq ft) are key. And then there is the issue of thermal blocks, if you have a hotel room or dorm with a sleeping area, toilet room, and closet…I don’t want 3-rooms, an energy modeler wants 1-thermal block combining all 3. I ran into that before and had some success because we (me and the architect) agreed that they would model all the rooms to help with the energy model (except for the rooms they wanted to use as “Typical” for their enlarged plans)

The most important thing I know is that it’s important to define what needs to go into the Revit model in the first place. As the Energy Modeler, we should be taking the lead in the effort, since we’re the ones that interpret the results and apply some level of engineering rules of thumb to make sure it’s an accurate model though I’m not sure if the typical energy modeler looks at it from a poindexter point of view yet.

Let me know if you have any other questions.

Support: Actually, that does tie into a question: Would the energy-modeler ever bother to make the changes in the Revit model without going through all the hoops?

Anonymous: Great question. But would you go into the kitchen and start adding vanilla extract to mom’s chili? In the Integrated Design Process, I find it best to go to the individual who “owns” his/her work to get what you need don’t

Support:  Understood. But if for the purpose of getting the energy-model created quickly and correctly, one might do a "save as", do the right edits, export to gbxml, and never tell a living soul what you did. Would that be effective?

Anonymous:  It may be that easy to just save a copy to your hard drive, but then you’re also allowing your team to give you what they want to give you, CRAP. So given the Revit ability to make these edits, it may be effective in the immediate future, but is it better in the long haul to build the expectations of what you the energy-modeler requires by all the team members?

Support: That’s a really good point. We want to make the process better and not just simpler. Thanks for giving us something to think about. I guess you just answered what the architect needs to know about energy modeling and Revit! Thanks.

Discuss below ↓.  What do engineers want to know about Revit? Any Architect comments on what the engineers should know?