Friday, April 17, 2015

Revit MEP - Circuit Length Calculation

I received an email asking if I thought it would be possible to use a Line Based family to calculate wire length for circuiting purposes. It was prompted by reading an earlier post about using them for Egress Path calculation and documentation. I think it's a reasonable approach for Egress Paths because there is no such tool or concept already in Revit.

Electrical circuits on the other hand do calculate their length already, granted it does so simplistically. It combines the X/Y/Z distances of the devices from the panel (and each other) to arrive at a total circuit length.


A friend some years ago sent me a PDF that showed a bunch (a couple shown above) of different equipment and device layout schemes he did to better understand how Revit arrives at a value for Circuit Length. What it shows is that Revit does nothing to factor in obstacles which force the wiring to go up or down or around the things that are more than likely going to increase the total circuit length.

To be fair...how could it really? How detailed is the model? How long do we want the software to interrogate the model, the linked models to do a better job? It's a bit like requiring all conduit to be modelled, even 3/4" conduit feeding single gang boxes in a wall when there isn't a single stud in the model. Like with so many things in life, it's about context.

It's one thing to put a single gang box on a wall to indicate one is required here and another thing entirely to run conduit to all the way to it when you can't be sure it can really go there. Or like showing a pair of outlets back to back on a demising wall in a residential project where fire rating and sound attenuation would require them to be separated by a minimum distance.

Some things are still conceptual (schematic) in nature even in fairly detailed models. If we start modeling every stud then perhaps it becomes more reasonable to expect more system detail too. Then again if I have to create a run of (15) 3/4" conduits across a wall or ceiling I probably ought to model that situation because it's going to take up a lot of space and everyone else ought to be aware of it.

It's also been my observation that no matter how good software gets at a task there are always outliers that dismiss its results as still wrong. That written, it does matter and Revit should improve how it does calculations and how much say we have in the outcome because the length it calculates is also used internally to contribute to other calculations like wire sizing and voltage drop.

Setting aside how circuit length should be calculated (it might surprise you to know that engineers don't always agree on this), I'd consider this approach if my task was to determine how much wire was needed, a little closer to actual requirements than might show up in the circuit properties. I'd create a schedule focused on Electrical Circuits.


What you see above: I created a couple panels and added a bunch of duplex outlets. I assigned them to circuits. The schedule's second column is Revit's calculated length, no more effort on my part than placing devices, creating circuits and choosing a panel.

I sorted the schedule by Panel and then Circuit, provided a header for Panel and footer for totals. I added a parameter for Length Factor (a number) and then a Calculated Parameter for Total Estimate (a length) which uses a formula of Length Factor * Calculated (column 2).

Then I consider each circuit's circumstance and enter in a factor that increases or decreases Revit's own calculation according to how easy or hard the actual wire run or routing will be...or at least what I think it will be. A factor of 2 doubles the length etc. This calculation doesn't factor into load calculations like for Voltage Drop...but then neither would using a line based family.

This doesn't account for situations that might share a neutral (or ground) or runs that are comprised of individual conductors in conduit (like THHN or THWN) or a wiring combined into a common jacket like Cerro's NMB (a typical household wiring product).

That's the risk/difficulty of automatic calculations, the closer you examine situations the more outliers there are. It can be a bit like arguing about something being 99.6 percent correct. If it costs another $1000 to get to 99.9 or 100%...is that difference worth it?

Thursday, April 16, 2015

Revit 2016 - Open Sheet

If you read this blog much you know I like subtle stuff and this is right-click subtle. We can already sort the Views portion of the Project Browser so that only views that are Not on Sheets are listed. To see those that are on sheets we just scroll down to the Sheets portion of the Project Browser instead.


Revit 2016 brings us a new feature which allows us to right-click on any view and choose Open Sheet for any view that IS on a sheet.


Naturally if the view you right-click over isn't on a sheet then the choice is disabled.

Wednesday, April 15, 2015

Revit 2016 - Place Rooms Automatically

If you've seen a demo of Revit MEP and Spaces or if you have used Spaces yourself then you may already be familiar with the new Rooms version of Place Spaces Automatically...called( shocking I know) Place Rooms Automatically.

This will create new rooms in all room-bounding elements on the same level with one click. It's like a shotgun blast of rooms, fill all the rooms. You'll find it on the Architecture tab > Room and Area panel > click Rooms then a button for Place Rooms Automatically will appear on the Modify|Place Room tab.


All the room-bounding elements that can define a room will end up with a room created. All the Rooms will share whatever Room Name is entered in the Properties panel when you start the tool. Their number will be increased incrementally from whatever the next available number is.

Practically speaking the Spaces version works better than this one because engineers need to create spaces where nearly all of the rooms are in the model (usually a linked model) already and the Space Naming Utility can speed up matching Space name and number to Room name and number.

If you are careful to create a list of rooms for your project in a schedule prior to having walls or at least at roughly the same time as walls are getting sketched this tool won't really help. If you import rooms from a list in Excel it won't speed up their placement because it will just blast new rooms into any valid room bounding area. It won't create rooms where rooms you've already placed are though.

If you're looking for a quick way to make rooms and don't care about naming (or other data) yet then this tool may be perfect for YOU!

Tuesday, April 14, 2015

Revit 2016 Trial Versions - Do Not Install the Wrong Version

A post of caution - If you are tempted to download a trial version of Revit 2016 please keep in mind that it comes in three trial flavors:
  • Revit
  • Building Design Suite (BDS) Ultimate
  • Revit LT
Let's imagine you're anxious to check out the new release and just download and install a version that you don't already have a license for with the expectation that you will just activate it for your particular license later.
PLEASE DON'T DO IT!
If you do install a version you don't own then you'll get to REMOVE that version and INSTALL the version you really need instead.

The installation is perhaps the least of it since the download time (the installation files are large) can be significant so I'd be really sad if I downloaded BDS Ultimate thinking I could just install it and then authorize it against Premium.

NOPE... uninstall, download correct version and install. I'd be wailing and gnashing my teeth...

Don't go there, wait for your correct version to become available to you via the subscription center. Forewarned is four-armed (as I read recently)...

Monday, April 13, 2015

That Time of Year Again - Revit 2016

The media embargo has been lifted for Revit 2016 so we're beginning to see some information surface on blogs and other sites. Fwiw, people involved with activities that carry an NDA (non-disclosure agreement) aren't permitted to discuss things they are aware of until their particular agreements are lifted. Naturally Autodesk would like to manage what is being said about their products when they release new versions, or at least be the first to start the conversation. The internet increasingly makes this impossible.

Dan Stine wrote a nice article describing the rendering changes we'll find in 2016. It will seem a little like deja vu all over again if you remember the transition from Accurender to Mental Ray. Read Dan's article, he explains it all quite well.

Luke has been sharing links to download different versions of Revit 2016 (and other Autodesk products). I'm refraining from doing so until I'm free to do so. In general Revit, on its own, gets released a bit earlier than the versions that are considered part of the Building Design Suite. I'm waiting for the latter personally.

Jeffrey (aka The Revit Kid) wrote a post earlier today about this subject too.

If you visit Autodesk's Revit pages you'll find new information is trickling in. For example there are some new Feature descriptions HERE now. Here's the Revit 2016 versus Revit 2016 LT COMPARISON. No such thing as LT for MEP users still, sorry...you're not considered light-beer drinkers.

This is also the time of year when the wailing and gnashing of teeth begins with renewed vigor. I think Autodesk manages to stub their toe each year by not adequately preparing their customers for their longer term plans and goals. Seth Godin weighed in on Hope and Expectation with his timely thoughts. Maybe it isn't possible to do that with as many customers has they have, or their frequently stated restrictions on forward-looking disclosures made by publicly traded companies? Seems to me they could do better.

As such this means each year we manage to build up hope that this year will be more awesome than the last (or the skeptic thinks less awesome). For example if we think that Revit 2016 is going to be transcendent then consider (it's my understanding) that, if you've got an active subscription and installed 2015 R2 already, you've already seen a percentage of 2016 features. The 2015 R2 is/was an early release of features slated for 2016, released early for subscription customers only.

Less surprise for you...because you're already on the inside track...

Based on what is published on their site so far, the big push with 2016 is:

A360 Collaboration for Revit (aka C4R)
Performance (more fasterer Reviting)
IFC Interoperability
Dynamo Integration
Fabrication and MEP
Structural Analysis and Modeling
Site Designer (part of R2 release only, now formally released to all 2016)
Online Analysis Feature Enhancment/Improvements
View and Tools enhancments (Reveal Constraints, Perspective View editing, PDF Exporting)

I have been quite pleased with the significantly improved performance experience with the 2015 release all year. I found myself resenting any work that required 2014 (or worse...earlier releases) very quickly. If 2016 stands on 2015's shoulders the way I've been hearing it does, then I'll be really happy to use 2016 too, right away.

Also keep in mind that, if Autodesk keeps to their timeline, next year, around this time, it will cease offering what they call Perpetual Licenses. They'll honor existing contracts/subscriptions but all new purchases will either be what they are calling Desktop Subscriptions or Cloud Service Subscriptions. Check out their BUY page for details.

I'm looking forward to getting to work with 2016.