A wind farm close to Almere, the Netherlands. Eneco has invested heavily in wind power, in part so that it can assure environmentally minded customers that their power comes from cleaner sources.
Credit: Ilvy Njiokiktjien/The New York Times

AMSTERDAM — When Eneco, a major Dutch utility, tested a promising energy monitor in several dozen homes, things could not have gone much worse. The company making the devices failed to deliver enough of them, and some of those provided did not work.

But when Eneco sent workers to recover the monitors, something strange happened — a tenth of customers refused to open their doors. “They wanted to keep it,” said Tako in ’t Veld, a former Eneco executive who now leads the “smart energy” unit at Quby, the company that makes the energy meter. “They were so happy with the energy insight.”

The test in 2010 was part of Eneco’s efforts to adapt to upheaval in the energy […]