Five of France’s best-known buyout firms have launched the first collective effort to reduce carbon emissions among portfolio companies in the latest sign of growing investor demand for improved environmental and social governance.

French firms Apax Partners SA, Ardian, Eurazeo, LBO France and PAI Partners have launched Initiative Carbone 2020, aimed at cutting CO2 emissions and publishing portfolio companies' carbon footprints by 2020, according to a statement.