Computers are transforming all aspects of design and lighting is no exception. Literally hundreds of different software programs are now available to assist in verifying and visualizing designs. More come on the market every month. Here's an introduction to some of the capabilities and limitations of lighting software as well as ideas on how to select the right software for you.

"Lighting software is a study tool," says Emlyn Altman, 3D CAD/lighting specialist at Gensler in Washington, D.C. "It's used to help verify what the designer may already know or point out an issue that may not have come up." The software illustrates light levels graphically through any of a variety of methods, from simple outlines on a two-dimensional floor plan (isofootcandle lines) to a false color plot (in which different light levels are represented by different colors) to a full three-dimensional rendering.

"A number of the packages are sponsored or developed by fixture manufacturers," says lighting designer Mike Barber of The Lighting Practice Inc., Philadelphia. "We try to shy away from them because you don't want to be affiliated with a particular manufacturer. As designers, we want to come up with the best possible solution, and if we use one manufacturer's package it may be misconstrued." The Lighting Practice primarily relies on leading software by two independent developers, Lumen Micro by Lighting Technologies Inc., Denver, and AGI32 by Lighting Analysts Inc., Littleton, Colo.

"Each piece of software has its little niches to do a mix of things," says Barber. "AGI doesn't do daylighting, but it does odd-shaped irregular shaped ceiling conditions better than Lumen Micro." Both software packages can import photometric data, showing the pattern of light emitted by a fixture, from any manufacturer. "Most larger manufacturers let you download data from a Web site, or if that fails, local reps can supply it on a disk. Technology has really caught up," says Barber.

Lighting designer Paul Mercier of Stebnicki Robertson and Associates, Calgary, Alberta, used AGI32 to design lighting for the Canada Bruce Department Store, Vancouver, B.C., Canada. The project was a two-story high, 11,000-sq.-ft. facility with an open structure. Half the store had two levels with an interconnecting staircase. "The challenge was to provide a suspended lighting fixture system from the upper most level with a bell-like luminaire," Mercier explains. "The architect could not picture the lighting effects without the aid of a model, which we provided with AGI32."

Mercier continues, "Display lighting has to have large contrast ratios between circulation areas and the product, usually 10 to 1. The rendering allowed both the architect and the owner to see that the system proposed could achieve these results. The renderings were emailed over the Internet as a .bmp file from Vancouver to Calgary and from our office to the architect's office."

Although professional designers can be relied on to understand the limitations of lighting software, retail clients will need some explanation. "Even though most software can do visual aids such as rendering or even simple massing models, I tell people to not rely solely on the results," says Altman. "Like a TV monitor, it's easy to adjust the brightness and the contrast. No two monitors are alike and every printer is different too. The images can be used for presentations, but care has to be used that client understands that this is a study tool, so it's always better to rely on the numbers."

Chip Israel, principal of the Lighting Design Alliance of Long Beach, Calif., seldom relies on software when designing for retail. "We do use it to calculate our general light levels, and we may use the computers to validate our first pass, but we do a lot more mockups," he says. "Nothing beats a mockup. It's the thing we learned from and it's the best way to illustrate solutions to our clients."

If you decide that you want to acquire lighting design software, the first step is to know what type of computer platform will be running it, Altman says. Most lighting design software is designed for Windows-based systems, but different packages will have different processor and operating system requirements. Next, determine how you intend to use the software so you can match your needs to the strong points of your chosen program. Know which other design software packages you use in your office so that you can find a program that is able to import and export compatible files.

Many software publishers offer demonstration versions or allow trial periods so you can try before you buy. Invest enough time in getting to know the software so that you can make an informed decision whether to pay for it. Some fixture manufacturers offer lighting design software for free. If you are considering one of these programs, be sure that it can import photometric data from other manufacturers.

"Some lighting software can only work with very simple shapes, like orthogonal boxes," notes Altman. "If your company does a lot of work with curved designs you'll want to take that into consideration. Some programs can't make models; you have to build them in outside software and bring them in. Some can do reports, whether it's a fixture schedule or an overall report showing how many of each fixture are being used. Some will have a limit on how many luminaires and objects you can use in a design study. If you need to do a calculation for a whole building or a really large room and you want to show all the different objects, can the software handle that amount of information?" No matter which software you choose, beware of Murphy's law: whatever can go wrong, will—especially when you are under a critical deadline. "Save early and save often," advises Altman. "Have backups. Maybe even save your work as a separate file. It takes less time to hit that save button than it does to recreate three hours of work."