Calgary has finished replacing 80,000 street lights with LED bulbs more than a year ahead of schedule.

The project cost $32 million and is expected to save the city approximately $5 million a year in electricity costs.

The new LED fixtures focus light on a more narrow area, the city said, concentrating illumination on streets and sidewalks and reducing light "spillage" upward, thus reducing light pollution.

Astronaut Scott Kelly tweeted a photo of the city from orbit  in November 2015 that showed the transition in progress.

City roads director Troy McLeod said the energy savings will be used to do lifecycle maintenance on other streetlight infrastructure such as light poles and underground wires.

Some of the city's underground wiring is more than 50 years old.

There are about 90,000 street lights in Calgary.

The city says it is still looking at ways to convert the remaining 10,000 to LED bulbs but noted many of them are "decorative in nature" and require more specialized fixtures.