"The companies interested in long-term incentives, mostly foreign subsidiaries, are now accepting that they have to do it on a cash basis, with the cost consequences that entails, " says Robert Sperl, a compensation consultant at WatsonWyatt London.

FORBES: Capitalism is contagious

But projects such as the Bahnstadt show the energy revolution and European efficiency goals "have put very low energy buildings much more strongly in investors' focus, " said Stephan Sperl, a spokesman for German state lender KfW Bankengruppe, which offers low-interest construction loans for energy-efficient residential buildings.

WSJ: German Project Aims to Save Energy