Firefighters rappelled down the Palliser South tower on Aug. 29 to secure a pane of glass. Firefighters rappelled down the Palliser South tower on Aug. 29 to secure a pane of glass. (Submitted by Eric Vondran)

Shards of glass that fell from a Calgary building under construction had nothing to do with unsafe work practices, says a city investigation.

A window on the 20th floor of the Palliser South tower at 140-10th Ave. S.E. shattered on Aug. 29, sending shards onto the sidewalk and cars below. No one was hurt.

The glass in question may have been fractured along the edges, and a crack may have spread due to "inconsistent pressures and temperature fluctuations," concluded Kevin Griffiths, the city's chief building official, in a statement released Thursday.

"Proper safe work practices were in place," he added.

City and occupational health and safety officials have been busy probing a string of construction-related incidents in the downtown area.

A mobile crane at the Bow complex on Centre Street between Fifth and Sixth Avenues S.E. fell off the third storey on Saturday, smashed into some windows and was left dangling over the construction site.

That same day, a piece of scaffolding blew off the 19th floor of the Penn West Plaza building on Ninth Avenue. No one was hurt.

On Aug. 1, Michelle Krsek, 3, was killed after being struck by a piece of corrugated metal. High winds had blown the roofing material from the 18-storey Le Germain hotel and condo site at 112 Ninth Ave. S.W.