Bentley's "BIM for Green Buildings" Executive Summit

With green rapidly emerging as the new global mantra, it is hardly surprising to find AEC technology vendors jumping on the sustainable design bandwagon, particularly those developing BIM (building information modeling) solutions. One of the most significant aspects of BIM is its ability to capture the description of a building in a semantically intelligent format that can be analyzed to study different aspects of its performance, including those related to energy use. Thus, there is a natural correlation between BIM and green buildings; in fact, I would even go so far as to say that if there ever was a technology "in the right place, at the right time"—at least in AEC—that has to be BIM in the context of sustainable design.

Of the leading BIM vendors, Graphisoft has traditionally been considered the front-runner in supporting energy analysis with IFC support and strong links from ArchiCAD to tools such as Energy Plus, ArchiPHYSIK, Ecotect, and RIUSKA (see more about this on Graphisoft's website). For Autodesk, sustainable design is rapidly emerging as a key focus area, as was demonstrated by presentations at Autodesk University 2006 and by its recent partnership with Integrated Environmental Solutions (IES) to closely integrate IES' building performance analysis tools with Revit. Bentley, in turn, hosted a one-day "BIM for Green Buildings" Executive Summit last month in New York, which I had the opportunity to attend. The event was focused on exploring the evident synergy between the new BIM-enabled design methodologies and objectives in sustainable design through a series of "best practices" seminar sessions by firms who were, according to Bentley, doing BIM and green design well, followed by an interactive "think tank" discussion with audience participation. The highlights of the presentations and an analysis of the key discussion points that emerged are captured in this AECbytes "Building the Future" article.

Seminar Sessions

The Summit featured five main sessions, the first of which was by Bill Barnard and Myron Bollman of the Troyer Group, a full-service AEC firm providing planning, design, and construction services, for whom sustainable design has been an important component of its work right from the start, long before the LEED (Leadership in Energy and Environmental Design) Green Building Rating System was even established. Now, the firm is a charter member of the United States Green Building Council (USGBC), and has multiple staff members from each discipline in the organization trained in LEED. Most of the firm's presentation at the Bentley Summit was focused on describing the various green features and LEED strategies it had incorporated on some of its key projects. The firm has been using Bentley's solutions for over 10 years, including site analysis with GEOPAK Site and Google Earth, architectural design with Bentley Architecture, structural design and analysis using the integration of RAM and STAAD.Pro with Bentley Structural, HVAC design with Bentley Mechanical and Trace, and conflict detection with Bentley's Interference Manager. It was not clear if the firm was actually using BIM to further sustainable design in its practice, but the presenters did highlight what was needed for BIM and green design to come together: the ability to integrate necessary information such as materials, building loads, lights, occupants, climate, building codes, and so on into the BIM model so as to be able to carry out interactive analysis of different green design aspects, particularly at the preliminary design stage; linking manufacturers' product data into the BIM model to incorporate accurate material information for analysis; being able to use the BIM model to explore the budgetary implications of features such as a green roof, reduced water usage, etc., both in terms of first cost as well as recurring costs; and linking the BIM model to LEED certification forms so that the certification process could be automated.

The bulk of the next session by Rodger Poole of Gresham Smith & Partners, a large multi-disciplinary firm of architects, engineers, planners and designers working in diverse practice areas, was devoted to describing the firm's implementation of BIM using Bentley solutions, the benefits that had been achieved, the challenges encountered and how they were addressed. BIM was used in the firm for a wide range of tasks including program analysis, space analysis, material takeoff, automatic report generation, 4D scheduling, procurement, building commissioning, and various FM services. With regard to the topic of green buildings, the firm was a member of the USGBC and was seeing a growing interest in sustainable design. Poole went on to suggest some strategies for enabling sustainable design with BIM such as building performance modeling, site modeling for more context-sensitive design, and the development of on-the-fly energy calculators. However, there was no indication if the firm was actively designing green buildings or if BIM was being used to explore sustainable design strategies.

Volker Mueller of NBBJ then provided an overview of BIM and sustainability in his firm. NBBJ, a leading architecture and design firm with a global presence, is a long-term user of Bentley's BIM solutions and is a frequent winner of Bentley's annual BE Awards—it won two of the six awards in the Building vertical announced at last year's BE conference. Its BIM implementation was described in some detail in my article on the BIM Symposium at the University of Minnesota published last year, and will therefore not be repeated here. With respect to sustainable design, NBBJ appreciates the growing green movement and the tremendous responsibility it places on the AEC industry, given that buildings account for the largest amount of energy consumption in the US. NBBJ has a Sustainable Design Group within the firm comprising over a 100 LEED professionals; it has a growing number of LEED certified projects and projects tracking to LEED; and it is also implementing sustainable design strategies in its own offices, with its Seattle office aiming for the LEED Gold certification. With regard to tying BIM and sustainability together, these are currently in parallel but interrelated tracks at NBBJ: BIM models are used for solar studies as well as glare and heat gain studies; radiosity based rendering of the models is used to study natural light penetration and determine how to get more light using shafts and skylights; and the use of Bentley's multi-disciplinary BIM suite allows better systems coordination. Many of the general benefits of BIM that NBBJ is realizing also have a green design pay-off: for example, the programmatic clarity achieved with BIM leads to a more economic and thus more energy-efficient design; and the improved prefabrication capability and gains in construction efficiency lead to reduced energy use. For detailed energy analysis, NBBJ partners with a consultant to produce CFD (Computational fluid dynamics) diagrams, but most often, these are produced too late to make any significant changes to the design. What is critically needed is an easier and interactive link between the BIM models and analysis tools, so that the design can incorporate critical energy-related feedback from an early stage. Most of the current links between BIM and analysis tools rely on IFC import/export, which is not an optimal process, as NBBJ has found. (For more on IFCs, see the article, "The IFC Building Model: A Look Under the Hood.")

The last two sessions at the Summit also reiterated the point that the overall benefits of BIM contribute to a greener building. The first of these was by Robert Stevenson of Ghafari Associates, a full-service A/E firm that is well-known for its cutting-edge multidisciplinary BIM implementation, especially in the automotive and aviation sectors in projects such as the new General Motors Lansing Delta Township Assembly Plant and the Detroit Metropolitan Airport North Terminal Development. Ghafari's BIM approach has been described in detail in a dedicated article in AECbytes, published in November 2005. On the subject of green buildings, the main aspects of BIM implementation at Ghafari that contribute to greener design are conflict resolution at design time and just-in-time construction, which result in energy savings because of reduced scrap, reduced transportation, reduced site disturbances, and shorter construction time. Ghafari is also pursuing LEED certification on several projects by incorporating green elements and design features, but it wasn't clear if BIM was directly enabling or facilitating this.

The final session by Michael Wick by General Motors was useful in providing the much-needed owner's perspective on green design, which in this case was in the context of the General Motors Lansing Delta Township Assembly Plant project that was designed by Ghafari. This project was awarded the LEED Gold certification, which is the first time an automotive project has achieved this distinction. It has also won the 2007 AIA Environmental Leadership Award. There is no doubt, some irony to a green design award going to a facility for manufacturing cars, as Wick himself pointed out, but General Motors was keen to derive the many economic, environmental, community, and health and safety benefits of green design. It had a LEED accredited professional as part of the team and pursued LEED certification to establish environmental leadership, reduce long-term operating costs, as well as have healthier buildings for its employees. The facility will use 55% less energy compared to other plants, and its energy usage is estimated to be 30% below the ASHRAE standard, which is quite a remarkable achievement.

"Think Tank" Discussion

While most of the individual sessions were focused either on BIM or on green design, some interesting points on how the two come together did emerge in the Q/A session and discussion following the presentations. One was related to the use of the IFC, which Volker Mueller had briefly mentioned during his presentation and which he elaborated upon a little more during the discussion. While NBBJ does use the IFC to send data to consultants, the process is quite involved and time-consuming. Every exchange is case-specific and needs proper mapping to ensure that the application exporting the IFC file includes all the data that is needed by the receiving application. The exchange has to be tested before being used on an actual project. Thus, the use of the IFC to facilitate interoperability between applications is that not straightforward and could account for the relatively slow adoption of IFC-based analysis tools in conjunction with BIM applications. A potential solution to this problem could be to have applications, both for building modeling and for analysis, that use the IFC as their native file format so that the entire rigmarole of import/export and case-specific mappings can be avoided. No such solutions are available yet, and it is not known if any are even in the works.

Another critical point that was brought up was the possibility that the design model might not be the same as the models needed for analysis. Just as we have had the long-standing debate about design models versus construction models (most recently discussed in the article, "The AGC's BIM Initiatives and the Contractor's Guide to BIM"), we are now confronted with the same question with regard to different aspects of energy analysis. There is no doubt that different models are required for daylighting analysis, for thermal analysis, for a detailed DOE-2 simulation, for a CFD analysis, and so on, as different kinds of building information is needed for these different analyses. The question is whether the design model created by BIM applications can include all the information that would be required to automatically derive these different models for different kinds of energy analysis. If we want energy analysis to become an integral part of the design process, this capability is very important, so that users don't have to expend additional resources to create separate energy-related models. But does this then over-burden the design model and make it too cumbersome to work with? It is difficult to know the answer to this question until we actually have such BIM applications. We do have structural BIM applications that combine a physical model of a structure with an analytical model that can be sent to structural analysis tools, but we are still far from a multi-disciplinary BIM model that integrates not just spatial, structural, and MEP information but also includes all the data needed for the varied types of energy-related analyses mentioned earlier.

With all the talk of analysis tools, it is also important to highlight the fact that the use of such tools does not dispense with the need to have energy experts and consultants working on a project. Just as structural engineers are required to analyze the information that comes out of a structural analysis tool, energy experts are needed to evaluate the results that come out of using energy analysis tools. Architects, therefore, should not just rely on the results from these tools to guide their designs but should ensure that they have access to the necessary expertise as well. This is also critical in view of the fact that there are regional differences in what is green, which is difficult for analysis tools to capture.

I was curious to find out if Bentley had a specific strategy for integrating its BIM solutions with energy analysis tools, given the fact that it had already acquired two leading structural analysis tools—RAM and STAAD.Pro—for better integration of structural design and analysis. Bentley users will be disappointed to learn that Bentley has no immediate plans to make a similar acquisition of an energy-related tool, although a Bentley executive did say that they weren't ruling out that possibility. Bentley also did not seem to be working on any close integration with an analysis tool provider, similar to the kind Autodesk has initiated with IES for Revit integration. According to Bentley, most energy analysis tools work with the IFC, so it will continue to rely on that to make the link between its BIM solutions and energy analysis tools, while at the same time, pushing for better interoperability and more open standards in the industry. This comes back to the same old "integration versus interoperability" question that the AEC industry has been grappling with, and at least in the area of sustainable design, we don't seem to have any good case studies yet that can allow us to form a conclusive opinion about which approach is more effective.

Conclusions

In the conclusion of my article from last October on the AIA CBSP Symposium on BIM for Building Envelope Design and Performance, I had emphasized that we need to hear more from architects who are successfully using BIM to design high-performing buildings. This was also true of Bentley's "BIM for Green Buildings" Summit. Most of the discussions related to how BIM can help design greener buildings were very theoretical rather than based on the practical experience of using BIM in conjunction with energy analysis tools. The lack of real-world examples, not just in these two events, but in industry forums as a whole, may be a troubling indicator that the technology is not there yet. BIM certainly has the potential to help design more sustainable buildings, but this potential currently seems to be a long way from being fully exploited.

Despite the lack of concrete examples showing how BIM furthered the cause of green design, the Bentley Summit was useful in highlighting some of the most critical issues related to linking BIM with energy analysis tools. Hopefully, it will also serve as a good exploratory forum for Bentley to think about alternate ways of integrating its BIM solutions with energy analysis tools rather than relying only on IFC-based interoperability to make the connection, which, as it was pointed out, is not without its share of problems. The cause of sustainable design calls for concerted and dedicated efforts from our technology vendors if BIM is to live up to its potential and really make a difference in making the world greener.

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.