Revit’s New Server and Conceptual Energy Analysis Capabilities

Earlier this year, we took a detailed look at Autodesk’s 2011 AEC solutions, including Revit, that were presented at the Autodesk AEC Technology Day. Then last month, we honed in on Revit Architecture 2011 and explored its wide variety of useful enhancements spanning across all areas of the application, including the interface, conceptual design, detailed design, documentation, the Family Editor, display and rendering, linked files and worksets, and the API. While the large number and wide range of enhancements were impressive, I also expressed some disappointment at the relatively minor enhancements for performance, large projects, and distributed workflows—there was still nothing to compare with the ground-breaking server-based collaboration capability that Graphisoft had engineered in last year’s release of ArchiCAD (described in the review of ArchiCAD 13).

It turns out that Autodesk has actually been doing some work on this front—it has just announced a “Revit Server” specifically for server-based worksharing to better support workflows for large, distributed design teams. This is being released as a free extension to the Revit 2011 platform (and thus applicable to all of the three Revit disciplinary BIM applications) which will be made available to its subscription customers starting September 30. Another major feature in the subscription release is a new “Conceptual Energy Analysis” feature that brings integrated energy analysis to Revit’s conceptual modeling environment, making it easier for designers to analyze different massing options to determine which would work best from a sustainability perspective. This AECbytes Building the Future article explores these two new capabilities of Revit and their potential impact on large team workflows and sustainable design for Revit users. While they are, as mentioned, currently targeted towards subscription customers only, it is likely that they may make it to the next general release of Revit and become available to all of its users.

The New “Revit Server”

Prior to the new Revit Server, all worksharing in Revit was file-based. When worksharing was enabled for a project to allow multiple team members to work with it, a central file of the project was automatically created on the LAN (local area network) of the office, and it worked as the master copy, storing the current ownership information for all the elements in the project and acting as the distribution point for all changes published to the file (see Figure 1). All users worked on a local copy of the central file, made edits to their local copy, and then synchronized with the central file to publish their changes to it. Revit’s transparent element borrowing feature made collaboration easier by automatically assigning ownership of an edited element to a user, which was then automatically relinquished when the user saved their local copy back to the central file.

Worksharing in Revit, as shown in Figure 1 above, worked well when all the team members were in the same office and only needed to work with the model on the LAN; it was when teams from other offices needed to work on the same model that collaboration became problematic, as they were now required to access the central model across a WAN (wide area network), which was noticeably slower. Contrary to the popular assumption that this latency was caused by Revit’s large file sizes, it turns out that this was actually due to the communication protocol between the central model and local copies, which, according to Autodesk, was not optimized and too “chatty.” After the local copy is first created from the central model—which will, of course, take a longer time for larger files—subsequent saves and reloads to and from the central model transmit only the changed model elements back and forth and not the entire file. At this point, therefore, the file size is not a factor—the latency problem caused by the non-optimized communication protocol would be of the same magnitude, irrespective of the size of the file.

The newly introduced Revit Server technology addresses the WAN latency problem through some key new features and changes. To start with, it is introducing the concept of a Central Server located in any part of the world, where the central Revit models of projects would be stored, and Local Servers at each of the office locations, which maintain copies of the models that users in that office are working with. As shown in Figure 2, users will now need to access the Revit model only across a LAN as it is stored on the Local Server, avoiding the latency problems that existed earlier when accessing models across a WAN. At the same time, in the new scenario, the Central Server and the multiple Local Servers are being constantly synchronized to ensure that changes made to the local models are updated in the central model, which are then, in turn, updated in all the Local servers in different locations. Also, even though the synchronization between the Central and Local servers is happening over a WAN, it is using new communication protocols that are much faster than the earlier non-optimized protocols, ensuring that the central and local models stay constantly synchronized. (Of course, if two users save their changes at exactly the same time, there will be a temporary asynchronization.)

Another technological advancement in Revit’s new collaboration technology is that the central model on the Central Server is not stored as a monolithic Revit file but instead as a directory that lists individual data streams in the model. This organization of the model data in a more database-like format makes it faster and easier for the central server to exchange data with the local servers. Revit element permissions are now stored and accessed from an integrated database managed by Revit Server.

From the perspective of the end users of the application, most of these changes are behind the scenes and do not require any significant changes to how they use Revit on worksharing projects. The main interface change is a new “Connect to Revit Server” option on the Collaborate tab (see Figure 3), which allows them to connect to the Central Server that their Local Server has been configured to connect to (by their IT administrator or BIM Manager). It should be noted that a Local Server can connect to only one Central Server. Once the connection is established, the user can browse through the projects on the Central Server and open the one they want to work with. If another user from that office has already worked on that project, a copy of it would already have been created on the Local Server; if the project is being opened for the first time, a local copy is created at that time. If a user creates a new project and enables worksharing for it, the central model is placed on the Central Server. Users would typically be unaware of the local server because it is transparent in their daily operations. They would, of course, benefit from the speed enhancements enabled by having the model on a local server, accessible at LAN speeds. Also, having local copies of the model ensures that users can still have access to them if the WAN connectivity is temporarily lost for some reason. 

While the new Revit Server technology is available for free (currently for subscription customers only), its implementation does require some additional hardware and software such as Windows Server 2008 and 64-bit servers. There would also be some initial server setup processes, mostly likely by a firm’s IT systems department, and ongoing administration by BIM managers and/or project team leaders (using a dedicated set of Revit Server Administrator tools). However, for a large firm, these additional costs would likely be small part of their overall IT budget and could be regarded as a worthwhile investment if it saves on delays and frustrations when distributed teams have to collaborate on projects. One of Autodesk’s customers, Burt Hill, which was involved in the development and testing of the Revit Server, has been using it in production for three weeks now, and reports that it has greatly speeded up the work on collaborative Revit projects by teams distributed across its multiple office locations.

Conceptual Energy Analysis in Revit

Another key new feature in the Revit 2011 subscription upgrade scheduled to be released later this week, is the ability to perform energy analysis on conceptual massing models within Revit. All that is required is for a massing model to be divided into levels, referred to as “massing floors.” The program then generates an analytical energy model from the massing model by automatically rationalizing the form into thermal zones and building surfaces (see Figure 4). This is based on parameters such as site location, construction type, percentage of glazing, and several additional attributes—some of these come from the main project settings while others are defined specifically for the energy analysis. All of the settings can be fine-tuned to capture the project attributes as accurately as possible. For aspects such as glazing, you can specify the exact amount and position by actually drawing it out on the surface rather than going with a uniform distribution of the glazing percentage on the building surfaces. Accurate climate data can be applied by locating the site precisely using Autodesk’s Climate Server technology that integrates with Google Maps. If the surrounding buildings are modeled (they can also be only masses and do not need to be sliced up into levels), they will be treated as shading devices and their impact will be reflected in the analysis.

For the actual analysis, the Green Building Studio web service is used, so you have to be connected to the Internet for this to work. In addition to the energy analytical model of the building, the analysis also takes into account project attributes such as building type, hours of operation, HVAC systems, and so on. Default values are provided for each attribute, which can be changed if required. The analysis results open up in a separate window and are presented in the form of graphics, charts, as well as tables to make them easier to read. It is also possible to model multiple design options and run the analysis for each option to provide guidance on which is the best option for optimal energy performance (see Figure 5). While the analysis is running, the user can continue working in Revit.

The Conceptual Energy Analysis is undoubtedly a useful addition to Revit and demonstrates the integration between design and analysis that is facilitated by BIM. While tools such as Ecotect (which is also an Autodesk product) and IES allow more advanced energy analysis, they typically require the building to be defined in more detail, with walls, windows, floors, etc., rather than just a massing model In contrast, Revit’s new analysis capability allows architects to evaluate different design options at the earliest stages of building design and get comparative feedback on how they perform from an energy perspective. The concept is not that different from what Green Building Studio has allowed architects to do for several years now—compare and contrast multiple design options to see how they perform. Also, Revit is using the same Green Building Studio engine for its analysis. The difference is that Revit automatically creates the energy model from the physical model and brings Green Building Studio in to do the analysis without the user having to export the file out to it in gbXML or any other format. Thus, it helps to bring energy analysis closer to design, and therefore more likely to be used to guide design decisions.

Analysis and Conclusions

Both the new Revit Server and the Conceptual Energy Analysis capabilities are important additions to Revit’s repertoire and help to reinstate its standing as a leading BIM application in the AEC industry, since these were the key areas it was lagging behind in comparison to its competitors. ArchiCAD introduced both its BIM Server technology and its integrated energy analysis tool, EcoDesigner, last year, while Bentley has continued to enhance its project collaboration platform, ProjectWise, and has acquired energy analysis tools that now integrate closely with its BIM applications. The Revit Server, in particular, will do a lot to speed up collaborative design work among distributed project teams and should be greatly appreciated by large firms. It is still not a full-fledged BIM server like ArchiCAD’s, and does not provide a collaborative interface that is as easy and intuitive to use, but it is definitely a big improvement to how worksharing was implemented in Revit prior to it. Going forward, Autodesk will hopefully improve upon the server functionality as well as Revit’s worksharing interface to make collaborative design more seamless and intuitive.

The Revit Server does not do anything to solve Revit’s large file size problem that I pointed out in my recent review of Revit Architecture 2011. But according to Autodesk, the earlier latency problems with collaborative workflows were caused by using a non-optimized communication protocol rather than large file sizes, and as this problem has been fixed with the Revit server, the file size should not be an issue with worksharing. However, Autodesk does recognize that large file sizes slow down the overall performance of the application and is continuing to work internally on this problem, while at the same time developing enhancements to linked files so that they can be used more easily to break up a large model into multiple smaller models that still behave as a consolidated whole.

The new Conceptual Energy Analysis feature will also undoubtedly be compared to Graphisoft’s EcoDesigner, which was the first example of an energy analysis tool full integrated within a BIM application. However, the two are not really comparable as EcoDesigner is a more comprehensive analysis tool that requires a more detailed building model created with walls, slabs, windows, and so on; also, it is sold by Graphisoft as a separate module that can plug into ArchiCAD. In contrast, Revit’s new integrated energy analysis feature works with early stage massing models and is included for free with the application (currently only for subscription customers but likely to be included in the 2012 general release). While energy professionals maintain that energy analysis is best done by experts and the results of analysis tools can be misleading to non-experts, having analysis tools integrated within BIM applications is essential if we want analysis to become a more integral portion of the design process going forward.  

About the Author

Lachmi Khemlani is founder and editor of AECbytes. She has a Ph.D. in Architecture from UC Berkeley, specializing in intelligent building modeling, and consults and writes on AEC technology. She can be reached at lachmi@aecbytes.com.

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