There has never been one definitive program for lighting design, calculation, and rendering, and there isn’t likely to be. There is, however, the opportunity for better integration and compatibility among software programs, specifically with regards to computing and design modeling. Developers large and small are attempting to improve integration among the various platforms, but some industry watchers think these upgrades aren’t coming fast enough, particularly when it concerns building information modeling (BIM). Architectural Lighting spoke with lighting designers and software developers to determine where today’s lighting design, calculation, and analysis programs stand on interoperability, and what’s left to improve.
“The whole world of 3D exchange is still a very imperfect world—from taking a 3D model from one tool and bringing it into another tool,” says David Speer, director of sales and marketing at Littleton, Colo.–based developer Lighting Analysts. In 2011, the firm, which makes the widely used AGi32 photometric calculation software, sought to contend with the difficulties of exporting the complexity of a BIM model into another package, like AGi32, and found that existing shortcuts didn’t maintain the detail of the Revit model. They couldn’t make BIM better, so Speer and his firm had to make a tool that worked within the existing constraints.
“How do we do lighting in BIM?” he says. “It didn’t take anybody very long to say that the best way to do it would be right inside of [Autodesk’s] Revit, because you have the 3D model right there, you don’t have to re-create anything.” Lighting Analysts worked with Autodesk and its application programming interface to build ElumTools, a Revit plug-in for calculations. Though the tool focused initially on interior applications, the team is now exploring its use for exterior illumination.
Having to work around the lighting-related limitations of BIM, and Revit’s M/E/P package in particular, is common practice among both software developers and lighting designers, especially given the program’s ubiquity among architects and engineers for structural and interior design. “On the Revit side of things, the growing prevalence of LED lighting is missing,” says Bob Bell, a Seattle-based design technology manager for engineering firm Stantec. One shortcoming is that the Revit engine does not currently accept or utilize the IES photometric data files for LED luminaires. “The IES files are in a slightly different format and Revit doesn’t understand that format,” he says. Bell’s workaround, right now, is to export the file to AGi32, which can read the IES files, in order to generate a point-to-point calculation that then allows the project team to change fixture position and quantity within Revit—though they’ll still need to send any changes back out to AGi32 to ensure that the design remains compliant.
Matt Franks, an associate at the New York office of Arup, agrees. On his wish list is better integration between third-party software programs and BIM. “Just being able to do [lighting calculations] within the BIM software would be one of the bigger things we’re hoping gets developed in the near future,” he says. “To do the calculations in Revit works for very simple spaces but as you get into more complex spaces it doesn’t work particularly well.”
Other industry watchers fault Revit M/E/P for automatically generating schedules based on the fixtures included in the drawings, rather than allowing the project team to create a multiname specification within the program that automatically updates as the specs change. On the other side of the business, third-party developers have found issue with the modeling of material properties in BIM—while aspects such as color and transparency are compatible, texture maps that determine material reflectance have historically been missing. This is key for performing accurate lighting calculations and, ultimately, fostering compatibility between the tools used by the architects and those used by the lighting designers.
It’s easy to chalk up the incompatibility to megadevelopers not understanding—or, not caring to understand—how lighting designers work. In the lighting industry, the programs that do the bulk of the work are made by developers with small teams. That makes for slower update timelines. “It’s difficult to keep up with the sort of technology that users are expecting nowadays and deal with programs like SketchUp and Revit,” says Speer, one of roughly 12 employees at Lighting Analysts. “We have all sorts of projects on the drawing board, as usual, and inevitably only 15 or 20 percent of what we ever conceive hits the market.”
One way the industry is seeking to improve compatibility is through the Illuminating Engineering Society Computer Committee’s BIM subcommittee. It has been tasked with developing vendor-neutral recommendations for BIM and CAD software developers to help them better understand the parameters important to lighting designers.
Autodesk has developed its own tool, a Revit plug-in that doesn’t aim to replace existing rendering engines but rather supplement them by opening up basic lighting calculations to the rest of the project team. Lighting Analysis for Revit, or LAR, is based on Autodesk’s 360 Rendering engine and uses a bi-directional ray-tracing algorithm that shows electric and daylighting results directly in the Revit model. “What we’re trying to do with LAR is put a wrapper around the analysis process … use a very high-quality industry standard to make the front end much simpler so that during the design process, architects, interior designers—people that may not necessarily have specialized analysis or lighting design skill—can start to include that kind of analysis to inform their design process.” Ultimately, the future of BIM compatibility with lighting design software should seek to incorporate and improve the existing technologies that lighting designers use daily.
A list of references that discuss lighting-design software and BIM:
“Lighting Analysis in BIM,” Autodesk Sustainability Workshop. Available at: bit.ly/1GX2w32.
“Setting a Standard,” by Gideon Fink Shapiro, Architect, April 2014. Available at: bit.ly/1lkkySU.
“IES Position Statement: Integrated Building Design (PS-01-09),” by the Illuminating Engineering Society, 2009. Available at: bit.ly/1ROrKkl.