Let’s Get Ready to RUMBLE…Autodesk versus Bentley in the 21st Century…Part One…

Man, if you have told me 5 years ago I’d be in this spot, I would have said why the heck wasn’t I there two years earlier…I’m loving working at Gannett Fleming, mainly due to the great work environment and attitude of the employees. And it’s given me a chance to step back and take a look at the whole big picture of where we are in the design world right now. There are some parts that make me just go “wow” and other parts that make me go “c’mon…”. And that’s what my next series of articles will be about.

You all know I’m an Autodesk guy. We’re family, no matter how dysfunctional it may be. I grew up with them, and they’ve made my career…so you know what camp I’m in. But out in the real world, I’m faced with different priorities – with number one being to make sure I take care of my team, no matter what the circumstances are.

Enter the Bentley…we do a lot of work with government agencies, and as most of you know, they’ve had a long standing relationship with the brothers from PA. We have several projects where BIM has become a topic, but because they’re bound like Siamese twins to Microstation products, we had to make a decision – take the work on that platform or leave it. It ain’t smart to turn down opportunities like this, so you know what we’re doing. And besides – we’re already good at the design part, so I’ve been psyching myself up by saying it’s just a tool, and we can do anything we set our minds to. One saving grace is that most agencies that are not tied to GSA are just now figuring this out, so it looks like we're all going down together...or up, depending on the outcome.

So last month, I did the unthinkable – I went to the Bentley LEARN Conference, which was an experience for me...going to the "dark side". On a comparative scale, you can tell who owns the market by looking at the annual conferences. I had classes where there were only 5-10 people on the buildings and electrical side, with the most in one class being about 30. I’ve had bad classes at AU that had double that number, and that still doesn’t come close to the body counts we pile up in Vegas every year.

One thing I noticed right off the bat – Bentley users are every bit as loyal as Autodesk users…actually more like Ron Paul supporters (if you’re not into politics, you may not get that joke). My other observation about Bentley – please forgive me for this – is that they’re more like the hot Brazilian model that has multiple personality disorder. They’ve got some sexy stuff going on, but can’t decide who they want to be. But I was also really surprised to see familiar faces from the Autodesk world. Apparently, we’re not the only ones having to learn how to live in both worlds and get the most out of them...go figure...

And here’s my equal time for Autodesk. Yes, we’re family. And like the drunk on Saturday night hanging out with his pals, you know I’m going to be the one to say “I really love you guys…” before passing out on the floor. But like family, you got your own issues with identity…and I’m blaming the short attention span, app-based world we live in for doing that. You’ve gotten away from taking care of the core, and are playing around with these hot little numbers like Force Effect, Flame and Photofly. I know I’m the old spouse that will always be there when you get done with your infatuation, but come Monday, you’d better be ready to get back to work.

For this post, I’m going to keep my observations down to a couple of generic points, mainly about the user experience. Autodesk wins this hands down, but it doesn’t mean I totally dislike what Bentley has done. For starters, the ribbon interface that’s common to most Microsoft-based applications make learning these tools easy. And having common mouse button functionality also makes program hopping work smoothly. For example, being able to pick it and right click to change objects has been a mantra of mine for years. The context sensitive ribbons are making me like them more now, especially since they always show up in the right (side) place.

Microstation – c’mon. After all these years, let the ESC key get you out of a command. I know you want to be yourselves, but this ain’t 1990. I like the toolboxes, but give me something to replace the exclusive cryptic letter entry keys. You shouldn’t have to type in Y to get a feature similar to otrack – make the tool visible and clear on the screen. DOS is dead, guys…

Every tool should be available in specific graphical areas, especially ones that control alignments, snaps, etc. And the tools should follow the workflow process. For the most part, they do that in the toolboxes, but finding something anywhere else was pretty maddening.

 

The view controls in AutoCAD and Revit and view cube trump Microstation navigation, although I didn’t have any trouble getting around once I figured out the view number icons. Overall, the bottom line is that the user interface is in bad need of overhaul. Get out there and study ribbon technology – if you want to be competitive in the future market, you’ve got to figure out a way to make the user experience easier, not harder.

Now I will say this – since my focus is going to be the Substation and AECOSim products, the hook feature you have in substation is an improvement on the snap tool, since it can control direction. Sort of like the connector in Revit, it gives you a little more flexibility when it comes to adding a wire to a connection point. But it’s going to take a lot more than that to impress me. I could go on for a while, but it’s time to wrap this up.

And my next topic will cover one of the most important concerns I have in regards to BIM applications – the “I” and the relationship with the data. Bentley has definitely been playing in the database game a lot longer. What Substation brings is linking data the way AutoCAD Electrical, AutoCAD P&ID and Plant 3D should have brought to the Revit world...let's leave it at that. There are definitely two approaches going on, but I’m going to spend a little more time figuring out how Autodesk and Bentley plan on handling this before I comment on it. It’s one of the deciding factors in who’s going to be the real player in the market in the foreseeable future, so let’s see what these guys - both companies - are going to do about it.

Happy BIM’ing – David B.

Getting STEAMED about Training...on Autodesk Products

I've been riding the high horse about training for years. but one of my biggest complaints was that the education community wasn't keeping up with the technology. I know, it's tough...usually they move at the speed of government...

While I was cruising around looking for some online materials about energy analysis and simulation for the 2014 release (here's a great link, by the way - http://autodesk.typepad.com/bpa/2013/03/advanced-energy-analysis-with-green-building-studio-doe2-and-energyplus-support.html), I came across the Autodesk Digital STEAM Workshop.

This site is gear towards the Education community, and demonstrates how new technology, from AutoCAD to Revit, Inventor, Maya and 3D studio, can be integrated into a core curriculum from the high school level and beyond. It works in 3 levels:

- Level 1 provides the overview of working in a 3D world, reviews the industry and careers, and the relevant Autodesk software. Other resources cover emerging technology and packages such as Mudbox, Sketchbook, and videos on design and teaching. A section on sustainability covers what this means from the industry side, so students gain perspective and common sense on the importance of designing smart. A list of core competencies is included, so the instructor and student know what to expect, and what's important to understand in the software packages. Certification and skills testing is also provided in this level

- Level 2 gets into the expectations of the course, providing project examples that are sorted by software, subject, difficulty and time. By providing real-world project examples, the students and instructors get an idea of the effort involved, and the endgame results.

- Level 3 is the meat of the course. The students can produce their own projects, from a 30 hour individual project to a 90 hour team project. Putting real-world examples and work in front of the users is critical to retention.

The beauty of this is that it provides education institutions that are still mired in providing board drafting, basic  AutoCAD, or 3D modeling training on packages that are most likely not related to what the student will use in the real world, a clear path forward using the most widely recognized design tools. It's a shame that some schools refuse to do this - for example, one of my former schools still only offers Solidworks training for the engineering curriculum, including civil, mechanical, electrical and other programs that focus on building design.

So check out this website: http://curriculum.autodesk.com/student/public/index/index, and see what you think. If you want to position your students to have the greatest likelihood of getting a job, and be prepared to use the most common tools, then start here...

thanks - David B.

How to Mess up a Revit plan view...Fat chance!

You know I would have bet a million bucks that somebody in our office would never screw this up...but it happened, so let me explain, and tell you how to fix it.

Our example includes a project with multiple small buildings in one file, at the correct elevation and location on a site. One building's ground floor level sits 3' higher than an adjacent building. Normally, when you set a project up, you would link the architectural model, then copy/monitor the levels from the architectural model to have one common set of levels. From the copied levels, you would create a floor plan view for each level, for each building.

Now stop and think about this - how would you do it in 2D AutoCAD? You'd take a site file showing the buildings, and either do a separate drawing for each floor plan (old school) at 0,0 in each building. But if you were doing both buildings in one CAD file, you'd be tempted (hold on) to create one plan viewport around one building on a layout tab...then copy the viewport, and pan over to the other building...all while keeping that viewport the nice, same size. This results in EPIC fail on the BIM test.

In 2D CAD, you can get away with this - but you can't do this in Revit - why?

Simple - every plan view is associated with a level, in most cases, a primary datum level at a specific elevation. Everything you place in the view is related to the level associated with that plan. Even hosted items can give off data that relates to the floor plan level, such as an offset elevation on a wall. But if you take a view that's associated with one level, and simply change the crop region around another building (which has a primary datum level at a different elevation), it's going to be wrong.

So here's where the problem occurs. For example - a user adds a pipe thinking that 210 Basement has the 210 Basement level as the associated level. So they're drawing a sloped pipe to what they think is 7' above that level. But in the view, since the 210 level is actually 3 feet lower than where it really needs to be. So the pipe is drawn at 10', not 7', causing additional work needed to change the pipe to the correct elevation.

You can change the associated reference level to get the right elevation, but it's something you're forced to stop and think about...and do a little math. Make it a really odd number...and you're really messed up.

And guess what - you can't change a plan views associated level once it's defined. (BTW - I did try to do this with a view list, by including the associated level...but no joy on that approach). You can also screw this up on single building projects - by copying a lower or upper level plan, and then changing the view range for the view properties. This is also a massive fail - since non-hosted objects display relative offset heights from the associated level...ugh...

So the fix for the user is to create a new view that's associated with the correct level, and then copy and paste generic annotations like text to the new view. Tags and dimension should be re-created, but these guys are pretty quick to make again.

In the end, it boils down to a simple thing - when you are setting a project up - whether it's one building or multiple buildings - make sure you start by creating a primary floor plan view for each level. Make sure it's associated with the correct level. If you are duplicating views to save some time, ALWAYS check that associated level. This keeps the issue from spreading like a virus to the rest of the project.

PAY ATTENTION to the details...cutting corners catches you every time...

later - David B.

Revit 2014 Notes and News...

With the product launch of Revit 2014, there's a lot of activity going on at Autodesk. I'm happy to report that we (Gannett Fleming) are wrapping up a few models for Autodesk that will be used as a dataset for demonstrating the product for this release. The building, which is a small medical facility, is intended to show how a model would be defined and leveraged across all areas of a design project.

One of our tasks was not to create a completed design, but more of a 80-90% complete design, complete with flaws and design issues that might occur during a project. So there are some conflicts, a few ducts that need to be sized, and some fairly complicated duct and pipe routing. We also include electrical system components that help demonstrate 120/208 and 277/480 voltage systems, and how to create a distribution system. Schedules include lighting, panel, and space/zone design schedules.

While primarily using out-of-the-box families, we also brought in examples of manufacturer content from Mitsubishi Electric.The HVAC system is designed as a variable refrigerant flow system. This system utilizes traditional supply and return ductwork systems, and room specific units that utilize makeup air from an energy recovery unit. The zoned systems also include demonstrating how a make-up supply air system can now be connected to a return air system. This is an improved feature in 2014 - in previous releases, the systems that are connected together all had to be the same type. You can now connect ductwork between these systems, but the sizing tools become disabled. We added a system connector family as an example, to demonstrate how you could maintain system separation and maintain the integrity of the system for sizing tools, and still connect the ductwork.

The architectural model includes a variety of finish materials, and allows the user to experiment with different design conditions easily. We also worked with Autodesk consultants on the design to create an asymmetrical design, including small variations in levels. The structure combines both concrete and steel components, to help Autodesk demonstrate the different design tools in Revit Structure.

All in all, it was a great learning experience for us as well. It helped drive home how important having a single, coordinate shared parameter file was on a project, which is something we put into place a few years ago. We included an example parameter text file based on the shared parameters exported from the Mitsubishi families to give us common voltage, number of poles, and  other shared electrical connection parameters. This helps us avoid the issue of having duplicate name parameters in a project, which can make defining schedules a real pain.

One of the biggest improvements for us came with the graphics systems. I've been running Revit 2014 on a three year old Dell Inspiron 14R, with an i5 processor, 8gb of RAM and Intel HD onboard graphics. I didn't have to wait for views to regenerate themselves, even in more complex views such as a transparent 3D model. File opens and saves were also faster. For someone who hasn't had the money to upgrade their systems, this release doens't mean the end of the world - as long as you keep your models compact. I haven't tried it yet on some of our larger, more complex projects, but I expect similar improvements on performance.

Rendering is also greatly improved, whether you are working on your own workstation or in the cloud. A simple  medium quality rendering using exterior only lights took about 5 minutes to produce the image above, even on my old workhorse.

So when you get a chance to watch one of the Autodesk demos, check out the model (and promise not to laugh too much - remember, I'm not an engineer, I just play one on TV). Hopefully it will give you an idea of just how far Autodesk has come with Revit for all areas of design - and that you get as much out of it as we do. 

Think you can guess how much time it took to create the model? If you can, you win - well, nothing of real value other than a pat on the back...I'll post the actual time up later as a comment - you'll be surprised!

thanks - David B.

2014 Product Launches Start Today!

It's the silly season - time for Autodesk to roll out new software. David Light, as always, doe sthe best job of detailing new features, so here's his link:

http://autodesk-revit.blogspot.com/2013/03/whats-new-in-revit-2014.html?spref=tw

But in my little part of the world, which includes AutoCAD MEP, Revit and more, I'm keenly interested to see how Autodesk 360 is going to work out. Norb and I have been actively working to develop the Revit dataset for Autodesk, putting in some non-traditional HVAC systems to show how it handles more challenging designs. One tool we've used a lot is BIM 360 Glue, a great tool for sharing files via an extension. But the fact that you can upload and markup Revit files to 360 is what really got my juices going. You don't have to strictly depend on AutoCAD WS for collaboration, which doesn't let you edit AutoCAD Architecture or MEP objects anyway. So this pushes Revit further up the food chain for us when it comes to picking the tool for the projects.

The two big Revit MEP enhancements include the ability to place an air terminal directly on a duct face, and embed CSV files into families for part selection.

I'm also glad to see you can divide systems now - how many times have you tried to connect a chemical feed to a primary pipe line? If this works the way it should, then tapping a makeup air system to a primary supply air system should work much easier.

From an energy analysis standpoint, I like the fact that you don't have to have spaces and zones defined to create an energy model. While this may stymie some of the Trane Trace users (which still requires spaces and zones), maybe we can get better results inside of Revit - we'll see...

AutoCAD MEP has a couple of neat new things - for starters, you don't have to add property set definitions after the fact. When they reside in your template, they're automatically assigned to objects as their placed in a model. This is based on how you define your definitions, and especially your classifications - don't miss this step.

And finally - irregular shaped viewports - about time!

More to come - maybe the strength of AutoCAD 14, will rise again in 2014 - could it be....?

BIM and Hoops...March Madness is upon us...

Yeah, I haven’t posted in a while, but geez…I’ve been busy. But now that March Madness is upon us, office work is about to get pushed aside for what really matters in life – the NCAA tournament…

I'm not sure how much I ever talked about this, but I volunteer for a local non-profit that offers youth athletics in my hometown. For 13 years, I coached basketball, baseball and soccer, served on their board of directors, and ran their basketball program for 10 of those years. Last year, the town, in an example of a monumental government mistake, decided to stop working with the association that ran these programs on their behalf (and at no cost to the town) and run a smaller, non-competitive athletic program.

Another great example of a bureaucrat thinking they know better how to raise children than a parent (just ask our Wake County school program, who believes fundraisers should only sell healthy snacks such as carrots and celery instead of Krispy Kreme “hot and fresh” doughnuts…if you’re from the South you know what I mean…some folks have no concept of what a fundraiser means).So after 4 years of retirement, I'm back running the basketball program. It’s been interesting, but the season wraps up this weekend. We had 511 kids in our program (compared to about half that much in the town’s), and for the most part, we accomplished the goal of keeping the program afloat long enough to regroup and work on a new program using county facilities instead of the towns…their loss.

And that's where this story starts. So how does this tie into BIM? It’s actually pretty easy – you can take anything you learn in real life, and turn it into an object lesson. I came up with three of them that relate to both hoops and BIM.

1 – You can’t win if you don’t play…

Lottery players know what I mean…well maybe that’s a bad example. Whether is volunteer work or regular work, you're going to run into challenges and frustrations. But you never know how things will turn out if you at don’t at least put in some serious effort to succeed. How you deal with those frustrations is no different, whether you’re trying to move an old school architect into BIM or trying to get a coach to stop yelling at his kids.

So I’ve got assigned tasks for all the coaches, and one of them is that they have to stay and clean up after a game. I also deal with a lot of complaining about officials, parents, and more. I got an email from one of my coaches frustrated with the officiating, and complaining about the parents a couple of days ago. When I could finally rewind, I remembered that I was at his game, the last game on Friday night…and he left without saying anything, leaving me and the other coach to clean up. It ticked me off that here this guy was, complaining and leaving, so I had to call him.

We talked about the officials, about players getting techs for cussing, and the “rough” group of parents he had sitting behind his team where they weren’t supposed to be. After going through this, I brought how having to clean up behind coaches was a pet peeve of mine – so what was his excuse.

He told me, “I’m sorry, I hadn’t told you…I’ve been getting treat for a form of leukemia, and I had chemo all this week…it was just starting to get to me…”.

I had to stop – dead in my tracks.

That caught me completely off guard.

Here was a guy, volunteering to coach his kids and others in a game that everyone loves to play, and loves to complain about.

He’s dedicating his time to working with kids not just how to be better at the game, but work better as a team. He’s a great example of being in the game – he’s there because he was committed, not just to his kids, but to himself.

And he’s doing this while undergoing medical treatments that are tough enough, much less deal with the mental aspect of fighting cancer.

I didn’t really know what to say.

I stumbled through a discussion about a couple of friends of mine, and a parent of kid I coached who later passed away from leukemia. And I remembered how hard it was on his son and wife, and how young they were when he passed.

At the end, we talked about his upcoming chemo treatments, which he has at the end of the month – right when our tournament starts. He was positive about the potential outlook, and was ready to be on the court and lead his team. All I could think of to tell him was I’d be happy to help him with his team if had any problems that weekend, or just needed the support.

All too often we get caught up in what we’re doing, and don’t realize how fortunate we are to live in this life, in this country, in this time, where in just a decade, the survival rates from cancer have increased dramatically, but still paint our immortality in bold letters. We think we’re doing the right thing by clinging on to what we’ve done for years, but get to the moment where we wished we’d done something different when your clock shows up.

And I thought about how hard I’ve hammered some of my co-workers about not moving forward, when compassion and a little patience would have gotten me further. I still believe that improving your skills, working to better your process, not to make more money but to gain more time, with family, friends and loved ones, is what this is really about. I remembered the long days and nights I used to work (and that some of my co-workers still do), and it drives me more to make their lives better.

But ultimately, it boils down to a simple thing – if you choose not to participate in the game, then you’re just an observer. Basketball and BIM have a lot in common this way – if you want to be successful, you have to put in the time and effort.

2 – My new motto – Learn to Earn!

While all of this is going on, I’m starting to get frustrated with my nephew. Family is family – you love ‘em all, no matter how nuts they (or you) are. We got into a big discussion about entitlements, where he made a statement that every person should be “entitled” to a good job, food, healthcare, etc. And I wasn’t raised that way – neither were my parents, who I still consider to be a part of the greatest generation.

It’s funny how the new town program is built that way. Everyone gets the same playing time…nobody keeps score…so it can all be “fair”. After all, isn’t that what sports is about? And man, I couldn’t disagree with that more. Sports is like work – you only become successful when you can do something better and smarter than anyone else. That’s what kills me about the entitlement mentality – you shouldn’t have to earn something to get something. So does that mean that even though we’ve made a substantial investment in technology, worked hard to train our staff, spent countless personal hours honing our craft so we can be better prepared to support those who need us…that another company, that’s still stuck back using thirty year old technology, be given the same consideration as those who have made the investment? All in the name of being “fair”…

It kills me to see owners and facility managers that go strictly on price when quoting a job. To me, design is a relationship – and BIM is a tool that’s used to improve that relationship. I can probably go give somebody a cheap price just to upfit a single room, but if I’m not talking to my clients about the big picture – about how BIM, when used in the entire lifecycle, dramatically reduces and simplifies to overall cost of designing and maintaining a structure. When you don’t work to train your client, then you’re no better than the parent or coach who doesn’t teach the kids the value of effort. Reputations are earned – good or bad – by the actions you take.

What Learn to Earn means to me is not being guaranteed a successful outcome, but rather the value of effort, hard work and desire…all things needed to be successful in life. In order to win, whether it’s contracts or basketball, you have to learn what it takes to earn the business or the game. Failure is a critical part of learning, so when you take failure out of the equation, then desire gets lost. Ask any 9 year old how they feel after they lose that close game – and instead of coddling them, teach them what it takes to get past it.

In BIM, it’s earned by time. You have to use the tools and be invested in them to be successful. We are always telling our managers that you can’t get there by doing tiny little bits and pieces. The entire job needs to be modeled, as much as the software can handle it. And the data has to be integrated, down to a single source. Giving up their old defense, and learning new ways to win is always tough – but you never stop learning.

3 – The officials never affect the outcome of the game…

Try telling this to the coach who just lost a game because the kid didn’t hit the rim on his free throw, but one of his teammates grabbed the rebound and made the basket that won the game. The rule is that you’ve got to hit the rim, but the official missed it. I heard about officiating all year – how “unfair” it was, how many missed calls, how they did or didn’t manage the game.

The funny thing about it, the bulk of the coaches that were complaining were the ones that weren’t winning. Somehow they misconstrued their success with another person having the ability to affect their outcome. Basketball – as much as any other sport – is a team effort that boils down to execution. Are you able to execute a game plan, within given parameters, to gain a successful outcome – the win? It doesn’t matter how many fouls are called, if you don’t make more shots than the other team – you lose. One play only has a minimal impact. The outcome is a result of the whole body of work, so if you were lazy on defense, turned the ball over too many times, didn’t square up before taking a shot…these were more likely the reason why you lost.

We had a game against a team from another town, which turned out to be a travel team made up of 16 and 17 year olds. Playing against them was one of our 13-15 year old teams. They were getting pounded, as our team obviously wasn’t in the same class. After the game, one of the parents I’ve known for a long time came up raising Cain, asking me if this was what FVAA was boiling down to.

I told him he missed the whole point. What he hadn’t noticed in the game was the smallest player, a 13 year old named Demarcus. He was constantly hustling, harassing the bigger players, getting called for fouls, taking and making long shots…he never quit. I had coached his older brother, but even he didn’t have the fire in his belly the way Demarcus did. That’s a kid that I will go to bat for a million times…because he never accepted defeat, but instead fought all the way through it.

The parent missed the whole lesson – no matter how adverse your situation is, you never just quit. You don’t give up on yourself, your team, your players…when you do, then you become part of the problem. It’s easy to quit – that’s why so many people do it. Look at all the “CAD” guys that are having a hard time finding work. It’s because they quit working on themselves – they stopped trying to learn, stopped putting in the effort, to make themselves better.

It’s the same way with BIM. It’s not easy – in fact, it requires much more initial effort than just throwing lines on paper and calling it design. But the rewards are immense, because eventually, you do get that time back. And we won’t ever quit – working to improve our process, our work conditions, our impact on the environment, and more – not because it’s not easy, but because it’s the right thing to do.

Wrapping up this way-too-long article…

Technology and life moves forward inexorably, improving in many ways, but you have to recognize, and accept it, in such a way that you can better yourself and your life. This coach, this player and this opportunity to serve others helped remind me that recognizing the work and effort of others that take the thankless job, deserve the recognition and thanks…and our gratitude. And that quitting on yourselves and others is never the right thing to do. And that getting and staying in the game is the only way to be successful and happy in life. Observation is for the jealous…

Find that technician that’s been working overtime to get your project out the door, and learning how to use new software every day, and tell them thanks. Talk to the older engineer, the close to retirement project manager, and learn from them – they’ve got an entire lifetime to share.

And don’t forget to contribute to the office pool and make your picks early. Go with your gut and you’ll win every time.

Enjoy the tournament!

David B.

Getting in the Flow with Revit HVAC

Been spending some time trying to get more into the sizing part of duct for Revit… we’ve been working on a project for a client that required well formed systems.  When I turned the duct systems checking tools on, I kept getting some really nasty little errors that I couldn’t figure out…and a couple of items that should work, that didn’t…at least from my understanding of how duct systems should be defined. So here’s the notes from what I learned.

         Regardless of whether the program can define a system when adding  a duct or not, I found that systems normally aren’t “well connected” when you follow this method. I’ve gotten repeated errors, that I believe came down to how I was adding the duct.  The safest method for defining a system and getting the duct sizing results needed, is to create the system first by selecting the targets, such as air terminals. Selecting the source equipment (such as a VAV) once you’ve defined the duct system usually creates the most stable system, and results in the fewest errors with the data tables.

         This includes upstream systems, such as the primary air supply to the VAV boxes. One big issue we’re having with vendor provided air handling units is the lack of good, clearly named connections. No matter who the vendor is, open the family up and put in a connection name, such as primary supply or return air intake. This way, when you are defining the upstream systems, you can select the correct connection even if there are multiple connections.

         The biggest problem I ran into happened in regards to the flow direction settings at the connectors. In order for a system to be sized correctly, the source (such as the VAV box) should have the flow direction set to OUT, and the Flow Configuration set to Calculated:

  

         A loss method should also be specified – so if you set this to specific loss, make sure you put a value in here – leave it at 0 and you’ll get an error.

         The reciprocal is on the target, or air terminal. Check the flow connection, and make sure it’s set to In for supply air, and leave the flow configuration set to either preset or system. The default air terminals are set to Preset, but you can change this. If it’s set to Preset, flow factor is disabled, and you can set the loss method to coefficient or specific loss. As with the VAV, if no value is set for specific loss for pressure drop, you’ll get an error.

          
When using the Calculated/Preset combination, the airflow for the equipment is set to match the total airflow assigned to all components downstream. If you have 10 diffusers at 50 CFM, that means you’ll have 500CFM assigned to the VAV box as the calculated value in this configuration.

System flow configuration is a little different – instead of using an aggregate airflow total from all diffusers, the system will calculate the equipment airflow based on a percentage allocated to each air terminal.  If you set the flow configuration to System, and have the loss method set to specific loss, you can specify a flow factor (using a factor between 0 and 1 – with the total of all air terminals equal to 1):

If the loss method for a system flow configuration is set to Coefficient, then you can also set the loss coefficient value for the connector itself(and pressure drop will be disabled):

As with the specific loss method, if you leave these values set to 0, you’ll get an error.

Be aware that Revit already has a loss coefficient tables defined for fittings, based on ASHRAE  Duct Fitting Database, which assigns a loss to specific fittings and accessories. By assigning a coefficient directly to the air terminal, the Equal Friction/Static Regain methods for duct sizing will return better results.

If you are using specific loss, I’d recommend using a shared parameter for that value, so it can be changed without having to directly edit the connector in the family. Use the Associate Parameter tool to add the parameter. By using a shared parameter, you can also include this as part of a schedule or tag.

Here's the help file's description of what each of these settings is for:

This should help you a few of those nagging duct sizing issues - have a great day!

David B.