WASHINGTON—At least 3.1 million Americans are employed in green jobs, a sector that now accounts for about 2.4 percent of the nation’s total employment, the Labor Department says.

HUTCHINSON, KS—Siemens’ wind turbine nacelle assembly plant here has been awarded LEED Gold Certification for its environmentally responsible design and energy-efficient operating systems.

KARIYA, Japan―Denso Corp. has developed a new, more efficient radiator that is 40 percent smaller and lighter than previous models. The radiator’s tank is molded from a plant-derived resin.

DUBLIN, VA—Volvo Trucks’ assembly plant here is the first U.S. manufacturing facility to be certified to the ISO 50001 standards for energy efficiency.

POUGHKEEPSIE, NY—Linuo Solar Group Co., a Chinese manufacturer of solar panels and water heaters, is investing $100 million to convert an old IBM factory here into its North American headquarters. The company plans to hire up to 1,000 people by 2014.

FREMONT, CA—Before LEDs can be as cost-efficient as incandescent or fluorescent lighting, engineers must solve the problem of “efficiency droop.”

ALBANY, OR—A new factory here will produce super-fine carbon materials that can improve the performance of ultracapacitors, lead-acid batteries and other energy storage devices.

NORTH CHARLESTON, SC—Boeing’s new assembly plant here is getting much of its power from a 2.6-megawatt solar panel array on its roof. The largest rooftop solar installation in the Southeast, the array generates enough power for 250 homes.

FAIRLESS HILLS, PA—Gamesa Technology Corp. completed and shipped its 1,000th nacelle assembled at its factory here.

CHATTANOOGA, TN—Volkswagen’s assembly plant here has become the first automotive manufacturing facility to earn LEED Platinum certification.