BIM as a Framework for Sustainable Design
In a world of changing climate and environmental degradation, architects play a key role in the pursuit of sustainability. In this article, Karen Kensek offers digital tools that will provide up and coming architects with the necessary skills and knowledge to produce sustainable building designs.
Climate change, water scarcity, and environmental degradation are issues that should be addressed by architects. For this to be possible, architects must have the knowledge and skill to create innovate designs, predict their performance, use constructive feedback to make adjustments, and construct buildings properly. Although far from perfect, there are many digital tools to help architects and their consultants do this. The profession has also seen a growing use of digital models, especially in the form of building information models (BIM). BIM has many attributes that make it useful for the architecture/engineering/construction profession, especially its inherent nature as a 3d virtualization that can be used to exchange information with other software. As BIM is a growing part of the architecture profession, learning its use is imperative by students on the path to becoming architects. It is also possible to encode pertinent data in the BIM and export the information to simulation programs to create predictions for future energy usage, CO2 emissions, daylight availability, water usage, natural ventilation, and other analytic models. Students who are learning about BIM have the opportunity to examine its usefulness as a framework for sustainable design. This paper describes assignments in two BIM courses that lay down groundwork for acceptance of BIM’s role in enabling sustainable design. It demonstrates that classes can provide an opportunity to prepare future architects for the environmental challenges that await them even when the major subject matter of the course is mainly focused on other topics. Eventually, BIM, like CAD, will diffuse into the design studio and the profession, negating the need for its specific teaching. Perhaps, classes like these will encourage stealthy diffusion of simulation based methods that help to predict the performance of buildings in the hope of producing more sustainable architectural designs.
If one accepts the premise that sustainable design is a moral imperative, then it is critical that architecture courses are infused with knowledge that allows students to design environmentally friendly buildings. This applies to all the courses that students take, although the depth of instruction about sustainable design and emphasis would vary amongst them. This paper describes how the instructor has taken two building information modeling (BIM) courses and added a sub-theme of performance-based simulation into some of the assignments. These courses are electives (one undergraduate, the other graduate) that focus on BIM: 2d/3d coordination, parametrics, and interoperability. It is with the latter two topics, parametrics and interoperability, where issues of sustainable design have been inserted into the courses’ agenda.
Fortunately, BIM is very well suited in some regards for the inclusion of sustainable design calculations. Although one could add other topics into a BIM course, such as construction or facilities management or even office management and legal issues, interoperability issues associated with the 3d model are well exemplified by simulation programs. In addition to the discussions associated with file types, open standards, and the 3d model as a database, one can reinforce environmental concepts of energy consumption, day lighting, and the uncertainness of the results while providing instruction in software that students may later use with their studio design projects.
Types of Assignments
Although this paper focuses for the most part on the sustainable design assignments, they were only a partial percentage of the work completed by the students in these classes. For example, in the graduate course (spring 2011), there were ten homework assignments and a final project. The ten assignment topics were the following (unless otherwise listed, the primary software program used was Revit Architecture): conceptual parametric modeling (Vasari), whole building energy modeling (Vasari), introduction to families, parametric families, adaptive components (Revit and Vasari), BIM overview, 2d/3d coordination, rendering and animation, phasing, clash detection and construction sequencing (Revit and Navisworks), and performative BIM (Vasari, Weather Tool, Revit, Ecotect, Revit MEP, Green Building Studio, and 3ds Max Design demonstrated in class). The final project was called, “BIM in the Profession.” Student teams interviewed architects about the role of BIM in the office. Although some students asked the firms about the how they integrated BIM and sustainable design, most students concentrated on other issues. In spring 2011, about 20 percent of the assignments and the final project had to do with topics of sustainable design and how they related to BIM. This method compliments courses that focus primarily on the integration of computation tools including day lighting analysis within the design studio (Oezener et al. 2010) and courses that use BIM and sustainable design tools for analytical inquiry during the design process (Lin 2010).
Three types of assignments were tried over many years: BIM plus simulation software, BIM workshops, and parametric components for sustainable design. The first type consisting of exporting the BIM into other software (for example, to calculate heating and cooling loads, daylight potential, or CO2 footprint) was the easiest to implement but was also the one most prone to inaccurate results. The exact results could not be trusted, as the students generally did not have the proper academic background yet to understand, for example, how to create a correct energy model that would accurately predict the heating and cooling loads. The BIM was extremely useful for providing geometric and links to location-based information and weather data, but the nuances of occupancy, HVAC, zoning, and material definitions were lacking. These would come later in other classes. The instructor’s underlying intent was not to teach sustainable design—these courses are specifically about building information modeling – but to provide another layer of support for the cause of sustainable design by showing students that BIM could help them use analysis tools more easily.
Three important lessons were learned by the students: it is possible to use BIM with simulation software; don’t believe the absolute values that the computer calculates; and relative results are often more useful than a singular answer. As the students changed building orientations and watched as the heating and cooling loads reacted, they could gain some confidence in their strategies even if the absolute numbers were judged unreliable. Although design was not a part of these assignments, other professors have described their experiences in courses where simulation results provided feedback for a new design. This was demonstrated in one example, shading devices and window lighting “shovels” (Techel and Nassar 2007).
The second type of assignment required students to write about a way they thought that BIM could be used with another software program and then to create a set of directions for that specific example. This was done only with the graduate students as it was thought that they would have the necessary architecture background to come up with interesting workshops. The inspiration for this was a series of sustainable design exercises that Autodesk had produced (Autodesk 2010). The student results ranged from uninspired to good. The biggest hurdle the students faced was actually writing clearly so that other students could benefit from the knowledge that they had gained.
The previous two methods focused primarily on the characteristic of BIM to be interoperable with other software programs. On the BIM side, it was found that “interoperability” was still cumbersome at best. In fact, often, despite the hype that BIM is not just 3d CAD, in many cases the 3d model (just like a CAD model) was the only feature of the building information model that was exported to the simulation programs. Only the geometric data was exported. This harkens back to at least 25 years ago (there are probably older examples). Replace the words “Computer-Aided Drafting” with “Building Information Modeling” in the paragraph below from 1987 to see that some of the same challenges still remain.
“During the architectural design process it is helpful to get the energy analysis at various steps. Using the knowledge obtained from energy analysis programs, a design can be improved during the next step. … To promote such analytical design process, there is a need to develop interfaces between energy analysis systems and Computer-Aided Drafting packages to get the energy analysis using the drawing files.” (Jog 1987:1)
The third type of assignment challenged the students to produce parametrically driven architectural components for sustainable design. Unfortunately, although the assignment was fun and the students learned a lot about how to create parametric components, we ended up with relatively trivial results. A major problem was that the students did not know both the software and the formulas in building science well enough to create complex solutions. Customization, scripting, and programming direct connections between software programs would be an excellent advanced course, and there are architecture firms that are producing wonderful examples of this (Guttman 2011).
Three different types of student assignments and two other student examples will be discussed. These include BIM plus simulation software, BIM workshops for sustainable design, parametric components for sustainable design, other tools, and a thesis project on the intersection of BIM and sustainable design.
BIM plus simulation software
Many different simulation programs have been tried over the years including IES <VE>, Ecotect, 3ds Max Design, Revit MEP, and Green Building Studio. A pre-release version of Project Vasari was also used (and later, a full version of Vasari). The intent of Vasari was to have the students consider conceptual massing studies as an appropriate place to start preliminary energy simulations rather than wait until their designs had been fully developed.
Building Information MOdels (BIM) workshops for sustainable design
This assignment came out in fall 2007 and has not been repeated more recently, although many of the same software programs are still being taught. The students were asked to select one topic area that they had explored in the previous assignment. The intent was to demonstrate that a BIM program could be used either alone or with other programs to inform the architectural design process and provide methods of evaluating alternatives. To accomplish this, the students created an example, listed the steps to do an analysis, redesigned the original building, ran the simulation again, and then wrote a workshop explaining the process. Many different types of workshops were submitted: “modeling an array of solar panels and estimating the produced energy” (Bassam), “modeling the impacts of design changes on solar gain” (Buntine), “solar access analysis for new building design” (Chen), “perform a visual analysis of the areas of a building that have access to natural ventilation” (Eng), “sustainable window design exercise: LEED day lighting” (Hill), “determine appropriate building material, model it correctly, and orient it, such that it minimizes building heating and cooling loads” (Kumar), “determining the best location for solar panels on a roof” (Loghmani), “determine the daylight level within the building with its original design and then redesign the building by adding extra windows and skylight if necessary” (Ng), “trying different options of planting and seeing their differing impact-shadow and screening–on the design” (Quinn), “how Revit can help you complete some of the LEED points, more specifically ‘Site Selection Credit 4.1 – Alternative Transportation, Public Transportation Access’ of LEED” (Rossi), “determine the amount of tree and buildings coverage on a site and track the amount of shade provided throughout the day” (Scales), “designing a roof or other shading device that allows for proper day lighting based on the season” (Smolyanskiy), “using and showing sustainable materials in building” (Wang), “understand the basic principles of passive shading, why it is important, and to use BIM models to identify which design can be most effective per building exposure.” (Eguchi).
In some cases, the descriptions of the goals of the workshops were overly optimistic based upon the homework actually turned in. “Determine exterior glazing type for a building” by Shih-Hsin Eve Lin (Fall 2007) is a good example of the intent and execution of the assignment.
Parametric components for sustainable design
A hallmark of BIM programs is the ability to associate data with 3d parametric objects (Kensek 2009). These are examples of student derived “sustainable” components.
Other software programs, chosen for their ease of use, were shown in the classes over the years. These were not directly related to BIM but were useful for understanding basic concepts like solar path diagrams, psychometric charts, and weather data.
Thesis project on the intersection of BIM and sustainable design
Typically, Master of Building Science thesis topics focus on structures, environmental controls, materials, or sustainable design. For example, recent research topics have included the following: “biomimetic design of the building envelope: biological climate adaptations and thermal controls in the Sonoran desert” (Wiebe 2009), “solar thermal cooling and heating: a year-round thermal comfort strategy using a hybrid solar absorption chiller and hydronic heating system” (Kirchoff 2010), and “using kinetic facades to increase energy efficiency and building performance in office buildings (Hansanuwat 2010).
Xin Stan Zhao’s thesis investigated methods to demonstrate that a BIM is an effective means for predicting and documenting a building’s potential LEED score by evaluating its potential to be used in each of the LEED NC 2009 categories: interoperability with third party software, scheduling and parameters within the software, and the use of specialized components directly inside the BIM. It was his hypothesis that although it is not a requirement to use a BIM for evaluating LEED credits, it may be easier than other methods, and the BIM could also be used for more rigorous testing of sustainable design solutions (Kensek and Zhao 2011).
Building information modeling can provide a framework for teaching sustainable design issues, especially for novices, as it often allows for interoperability between building performance software programs and 3d models. It is also being used in the profession for design green architecture (Krygiel and Nies 2008). Currently there are numerous annoying technical difficulties and stumbling blocks, but if students are creating these 3d models anyway, there is no excuse for them not to start at least preliminary analysis of their projects as soon possible in the design process. The inclusion of these programs into the BIM courses is to encourage the students to become familiar with the tools, mentally synthesize their properties with information from building science courses taken previously and future coursework, and apply what they have learned. Recently the author has also been incorporating a short introduction to conceptual energy modeling into a required professional practice course for graduate and undergraduate students. The profession needs architects who understand the criticality of sustainable design, are competent with using software to predict building performance, and who create innovative, beautiful buildings that not only do little harm but also give back to the environment. Every instructor can help achieve this goal.
Thanks to my students for working through my endless homework assignments! I am especially heartened when I see the students take the use of BIM to other classes (for example, in a class that concentrates on energy flows in buildings) and have used the simulation programs that I have showed them for analyzing their studio projects. A preliminary poster on this subject was also presented in 2009 at ACSA (Kensek, 2009). The thumbnail image is by Fenty Muliadi, (student, Spring 2011), Revit sun path diagram and Ecotect daylight factor.
References and Endnotes
Autodesk (2010). This following is a link to a more recent version of the Autodesk Sustainable Design Curriculum; this link does not imply an endorsement; like many design curricula it has its own set of opportunities and problems. http://students.autodesk.com/?nd=content_box_layout_view&layout_id=24
Guttman, M. (2011). “Application Programming for Computational Design; A Case Study on Driving Revit from Ecotect,” Extreme BIM Symposium, USC, July 8, 2011. Guttman demonstrated the use of custom applications using Revit, the Revit API, Excel, and Ectotect for studying shading and solar insolation. This is just example of many tools being developed in architecture firms.
Jog, B. (1987). “An Interface Between CAD and Energy Analysis System, Integrating Computers into the Architectural Curriculum,” ACADIA Conference Proceedings, Raleigh, North Carolina, 1987, pp. 87-94.
Kensek, Karen. “Sustainable Parametric Objects.” AUGI | AEC Edge, http://augiaecedge.com/Current/default.htm, pp.31 – 35, Fall 2009.
Kensek, Karen. “BIM + : exploring the potentials of building information modeling for achieving sustainable design.” ACSA 2009, Portland, Oregon, March 26th-28th, 2009. Poster session.
Kensek, Karen and Xin Stan Zhao. “Using Building Information Modeling as a Tool for LEED Score Calculations,” BESS 2011 (Building Enclosure Sustainability Symposium – Integrating Design & Building Practices), Pomona, CA, April 2011.
Krygiel, E. and Nies, B. (2008). Green BIM: Successful Sustainable Design with Building Information Modeling. The students were assigned to read “Chapter 2: Building Information Modeling,” pp. 26 – 52 and “Chapter 6: Sustainable BIM: Building Systems,” pp. 165-208.
Lin, J. (2010). “Design for Quantitative and Qualitative Performance: A Pedagogical Approach for Integrating Environmental Analysis into the Early Stages of the Design Process,” Re.Building: 2010 ACSA Proceedings (Goodwin + Kinnard, editors), New Orleans, Lousiana, 2010, pp. 189 – 196. An interesting discussion of a class where “analytic inquiry [was used] as a means to evaluate design.”
Oezener, 0., Farias, F., Haliburton, J., Clayton, M. (2010). “Illuminating the Design: incorporation of natural lighting analyses in the design studio using BIM,” FUTURE CITIES, 28th eCAADe Conference Proceedings, ETH Zurich, Switzerland, September 15-18, 2010, pp. 493-498. BIM was especially useful in the studio described as it provided a method for making design decisions and then receiving relatively rapid feedback.
Techel, F., K. Nassar (2007). “Teaching Building Information Modeling (BIM) from a Sustainability Design Perspective,” Em‘body’ing Virtual Architecture: The Third International Conference of the Arab Society for Computer Aided Architectural Design (ASCAAD 2007), 28-30 November 2007, Alexandria, Egypt, pp. 635-650. This is just one of many excellent examples where professors are using BIM as the framework for sustainable design studies.