Household energy use in Prince Edward Island has dropped in the past two years, according to a national watchdog group.

The Canadian Energy Efficiency Alliance rates how each province encourages energy conservation.

Results are released every two years, and this year, P.E.I. improved its grade from a D to a B.

The Alliance said household energy use on the Island dropped 20 per cent thanks to programs implemented by the Office of Energy Efficiency.

Over the past two years, that office has done 4,000 energy audits and handed out grants to reduce home energy use.

But advocates for the environment say there is still room for improvement.

"We're seeing a shift toward more energy-efficient home construction," said Matthew McCarville of EcoPEI. "I think that's a trend that will continue and, hopefully, at an increasing rate."

Another reason for P.E.I.'s improved performance was the introduction of vehicle emission standards, which start this fall.

Environment Minister Richard Brown said a contractor will test emissions on all government and commercial vehicles.

Vehicles with the Department of Transportation and Public Works are already being tested.