"How important is safety to the CEO of a company?" Robinson said. "I find if they're paying attention to that, they're also paying attention to other aspects of responsibility."
How To Invest Sustainably
Some sectors, such as energy, present challenges to the sustainable investment approach.
Regarding its energy holdings, Allen said Parnassus generally invests in U.S. companies due to better corporate governance policies. It tends to favor natural gas because it's cleaner, but avoids companies plying the Marcellus Shale natural gas field in the Northeast due to water pollution concerns caused by hydraulic fracturing drilling, or fracking.
As such, Allen said Parnassus invests in gas companies in North Dakota and West Texas it has identified as drilling in a responsible way.
Elsewhere in the energy space, he said Parnassus frowns on coal and absolutely avoids nuclear.
Dalheim said Calvert sees natural gas as a bridge to address climate and national security issues, and it invests in companies involved with fracking. "Our approach is to engage them and ask them to be more forthcoming with foreclosure, and we've had some success with Devon Energy and Anadarko to improve their disclosure" about their fracking process, water disposal methods and the chemical makeup of their fracking solution.
"It's a difficult issue because natural gas is domestic, it's a lower-carbon fuel and it's a positive thing, but there are significant concerns regarding water quality," Dalheim said.
Robinson says Winslow looks at the alternative energy space from both production and consumption perspectives. "It's not just about producing wind, solar or geothermal, it's what can you do to reduce the consumption side," he said.
On the production side, Robinson likes First Solar, which he called the leading solar company both in terms of its technology and manufacturing processes. He also spotlighted a small Ft. Wayne, Ind.-based geothermal company called WaterFurnace that makes geothermal heat pumps for shallow geothermal operations. He noted the company consistently produces return on equity of 40%, and it pays a dividend.
On the consumption side, he spotlighted a small Canadian company called Pure Technologies that--among other things--measures water leaks in municipal water systems to help reduce wasted water.