Room Separation Lines Don't Play Well with Others

Please Use Sparingly

Room Separation lines are a necessary eval from an MEP perspective. There are times they must be used, and from an architectural perspective are completely appropriate.  Here is the rub, they don't just divide rooms, they also divide spaces. Spaces are used by MEP in place of rooms as they have more parameters pertinent to those trades.  The information derived from calculations performed either in Revit, or more commonly in external applications is stored in these space parameters. Now you may think if it should be two separate rooms, then we should treat them as two separate spaces right? Not necessarily.

The reading space above is separated from the lounge, stacks, and check-out spaces by room separation lines.  Unfortunately light from the windows in check-out and lounge will contribute to the lighting levels in reading.  Air being supplied to the stacks will flow into the reading space. But with room separation lines, there is no way to account for it.

When we are performing calculations for either lighting or HVAC, the two spaces communicate openly. The reason a room separation line was used in the first place is there is no physical separation. Light from one room will cross the imaginary separation line and impact the calculation for the adjacent room. The same is true for air and heat on the HVAC side.

Solutions for the MEP engineer are to use Zones as your export for analysis, which has other benefits as well. But if the doesn't make sense for the two spaces to be part of the same zone, then things get more complicated. There is no way from the MEP model to not have a room separation line from separating the spaces.  They must be deleted from the architectural model.  Then fake tags must be used to distinguish the two room tags from the architectural model, and they must be managed in the MEP model as well. Or the two rooms can be merged in most of the outside calculation platforms. If you are choosing to manage it outside Revit, you will have to be careful when updating to re-merge the spaces in your external software, and you will need to pick which of the original two spaces will be the container for the information.

Model It Right!

Another problem we see all too often with room separation lines is as a band-aid for poor model craft. Perhaps a room doesn't close properly due to an opening or non room bounding element that isn't obvious.  A room separation line is a quick way to fix the problem.  Unfortunately that gets translated in the calculation software as a wall opening. Assuming the line is drawn along the length of the exterior wall, then the room is seen as not having any surface separating it from the outside. To be brief, lots of calculations are reported wrong. 

Divide and Conquer

The ‘when to divide’ and ‘how to divide’ topic has a million shades of gray.  The process does have some overhead time required to setup.  When needed though, there seems to be three schools of thought on how to divide a project. The first is across the match lines. The second is by floor. Then the third is by discipline.

Well, for Architecture it makes sense to be able to divide by the match lines, but not for MEP. As of Revit MEP 2015, system information cannot be passed through a linked file.  Yes, you can tag through a linked file, but that is not the same as passing system information along.  If the electrical panel that serves an outlet is in a different file, then it can’t be added as a load to the panel.  Air Handling Units in one file, can’t add CFM’s from terminal units in linked files.  Largely, this approach just does not work for MEP.

The second approach of by floor has the same limitations. If the systems need to be able to connect vertically though the building, they won’t be able to. This leaves only one viable option left, dividing the model by discipline.

On large projects dividing the models is a must to gain efficiency, but on smaller projects, where is the cut-off for a return on the time investment?  Buildings 30,000-50,000 Sqft and smaller are generally manageable as single project files.  For larger projects, it makes since to create separate Revit MEP models. I prefer to divide them per trade (Electrical, Plumbing, & HVAC), then interlink each into the others by placing them on separate worksets unique to each linked file.  Finally setup the central file to inquire as to which worksets to load upon opening. If the workset for electrical is not selected upon opening the HVAC model, then none of the electrical objects will be loaded into active memory.  This can free up huge chunks of memory.  Dividing worksets into logical chunks helps with linked files even more.  Let’s say the electrical model is linked into the HVAC model.  To coordinate the ceilings, the workset for lights can be the only workset loaded into the HVAC model.  To manage the worksets within linked files use the Manage Links tool as shown below.

Some Background on Backgrounds.

Managing file size in Revit must be a priority for large projects; else progress will slow to a painful pace. There are many places to manage, but for the MEP engineer, the first place to start is with the background files. The architect's files that are linked in as backgrounds are really just there for the floor plan, and model coordination. It would be fair to say that everything in the linked file is overhead for the performance of your model. So make it a minimal as possible. Delete as much out of it as you quickly can. Every byte of information you remove, saves time for each person opening the project. Delete out all of the sheets, every one of them. You're not linking to their sheets, so you're not using them. Delete them. Delete the schedules, the legends, the sections, and elevations too! If you're not linking to the view, delete it. Purge the heck out of it, till there is nothing left to purge. Obviously don't get too carried away. Make sure you don't really need something before you delete it. But the more you can delete, the better off everyone will be. The only things I usually keep in my background files are overall floor plans and RCP plans.

Don't invest too much time into this process. I have heard of people spending an hour or more deleting stuff out. Make it a quick process, where you get the most bang for your time. If you have the resources, write a script to delete stuff you know you won't use quickly. Get the process down to 5 minutes or less.  I usually get Architectural backgrounds starting around 125 megs, and can reduce it to about 54 megs.  Your mileage may vary.

Retooling the Revolution

Retooling is often a phrase we here for factories getting an upgrade to make a new model of widget, or as an upgrade to help them produce the widgets faster.  I believe the AEC industry is in the midst of retooling for the Digital Design Revolution.  Why you may ask? BIM is producing more data then we know what to do with.  We need to become better at sorting though all this data to make educated informed decisions, without drowning. We need to learn to swim though the sea of data.

The AEC industry for ages has revolved around the all mighty drawing set.  The printed (or hand drawn) set of documents that communicated to the construction trades the extents and quality expectations of their work.  This is no longer the case.  The drawing set is being replaced by digital models.  Digital models heaping with data.  We need the ability to sort though the data, gather specific bits of it to make decisions.  The authoring software usually does a pretty good job of helping us do that, when it falls short, when we need a specific task not built into it, that is when we start to drown.  This is where we need to retool.  Accessing and manipulating databases is what we don't have the skills and tools to handle. Sure many of us learned how to script for AutoCAD,  or maybe to write a macro in excel, but how many of us have learned to write a macro for Revit, or an add-in even.  How many of us have learned how perform a query on an SQL database or to link it to real objects in the Revit database? Do we need to become proficient programmers in C#, Python, Ruby on Rails, or the next hot programming language?

This is the kind of retooling I am proposing.  I don't believe we need to all become programmers before we become designers and engineers, but these are the tools of this generation.  These are the tools that will differentiate us from the competition.  Perhaps we will hire a programmer on staff, perhaps keep one on retainer like a lawyer. No matter the arrangement, programming and data management needs to be part of the tool kit for the BIM world.

Use Excel with Revit!!!

I know what you're thinking, Revit does not support importing and exporting of data with Excel. Your right, natively it does not.  So right off the bat we need to talk about add-ins.  There are several out now that you can buy to allow you to create and sync data with Excel.

Schedule Sync

BIMLink

CTC's Spreadsheet Link

Rushforth Tools

And I'm sure there are more. Each has its pros and cons.  My personal favorite is Rushforth Tools.  The cost is very reasonable, and you get so much more then just the ability to use Excel.  Personally I wouldn't use Revit without it.  

Now there are some things to know before you start manipulating data with Excel, and pushing it back into your model. For starters, every single little object in a Revit model has a unique element ID, and I mean everything. Most of the add-ins will by default create a column identifying this property. Don't mess with it, ever. There really shouldn't be a need to, but it would really confuse the software for these values to change. It is a very good property to use for keeping track of things as it does not change. 

Next, what kinds of stuff might you want to change?  The limits are almost boundless here and will likely be an entire post itself in the future. Some brief suggestions, how about shared parameters used for scheduling, or coordinating your ceiling heights with the heights of ceiling devices, or pushing CFM values from your load calculation software into the spaces, and then to the devices in those spaces. I could go on, but that's just a sampling.  What kinds of data would you like to sync with Excel?  Do you have any favorites you are already using? Leave a comment and let's discuss.