In architectural terms, the 2007 World Series, which opens tonight in Boston, pits the Red Sox’s venerable 1912 Fenway Park against the Colorado Rockies’ 1995-vintage Coors Field in Denver—old bricks v. new bricks. Fenway is the oldest ballpark in Major League Baseball, but it’s receiving a makeover informed by the latest thinking on sustainability.

The Red Sox are planning to add photovoltaic panels and make additional green improvements with advice from the Natural Resources Defense Council. Although there is not yet a standardized way of greening a stadium, the Sox join a host of other ball clubs pursuing LEED-inspired, or LEED-aspiring projects including the Washington Nationals, Minnesota Twins, New York Yankees, and New York Mets. The NRDC is consulting with many of these teams, as well as Major League officials and NBA and NHL franchises.

“It’s enlightened self-interest (for sports teams),” says Mark Rosentraub, a sports economist and dean of the Cleveland State University School of Urban Affairs. “It’s a prudent response to the high cost of energy and there’s PR value, since everything they do is much more visible.”

As part of the upgrades at Fenway, which will happen in time for its centennial, the Red Sox are reusing bricks, sourcing materials locally when possible, and recycling construction waste, says Fran Weld, assistant development director with Baltimore-based Struever Bros. Eccles and Rouse, which manages the team’s off-season construction projects. They are also converting to fluorescent lighting, adding sensor-controlled fixtures, and installing low-flow plumbing. Changes already made have the team playing on a field that includes a sand filtration layer that moderates runoff into the city storm drains, and the grounds crews using less-toxic chemicals to maintain the field.

Sports facilities can be tough to green and they don’t neatly fit into existing LEED categories, observes Stephanie Graham, the sustainability coordinator at HOK Sport, which has helped design ballparks for the Nationals, Twins, Yankees, and Mets. The difficulties include massive peak energy demands, substantial parking requirements, CO2-spewing game-day traffic, and all-or-nothing usage patterns. “And passive solar is hard because there are only so many ways you can orient some stadiums,” she adds.

HOK and others are working with the U.S. Green Building Council to adapt the emerging a la carte LEED system to take into account what’s required to green sports facilities. Apart from the smart growth wisdom of locating a stadium or arena in an urban setting with access to decent public transportation, designers can green these buildings by increasing the amount of natural ventilation, installing on-site energy generation systems, and treating storm water run-off—all standard tactics. HOK’s sports-specific playbook includes using landscaping that requires less water and chemicals to maintain, building permeable parking surfaces, and sharing parking within multi-use complexes.

Given that individual teams operate different business models, presenting them with an array of sustainable choices works best. “Many teams obtain a lot of revenue from parking fees. Mass transit and carpooling could bite into that. Bottled water is another example,” explains NRDC senior scientist Allen Hershkowitz. “Each team is not going to be maximizing every environmental element.”

Whatever approach they take, one thing is certain: Big league sports teams have always obsessed over numbers—stats, attendance figures, salaries, TV ratings—now they’re beginning to run the numbers on carbon footprints, fuel prices, electric meters, and LEED scorecards.