Demko made 31 saves in his return after missing four games in NHL COVID-19 protocol for the Canucks (19-19-6), who have lost four of five.
"They're one of the better defensive teams in the League so a lot of it was them, but I'm used to seeing our team play with a lot more energy so I have to say that some of it was on us," Vancouver coach Bruce Boudreau said. "It's unfortunate, especially when you need the points. They were a beatable team tonight and we didn't take advantage of it."
Vancouver killed off Tyler Myers' match penalty for his check to the head of Trevor Lewis at 13:02 of the first period. Calgary had two shots on the power play.
"Tyler's a big guy. I thought he hit the shoulder pad first, but I'm not there in real time," Boudreau said. "I'll have to look at it a few more times on video before I really have an assessment for you."
The Canucks had a season-low one shot in the first period, coming shorthanded at 15:10 during Myers' five-minute penalty.
Vancouver's second shot came 7:04 into the second period.
"I think they were standing up pretty good in the neutral zone," Canucks forward Tyler Motte said. "When we did get pucks behind them, we weren't first to it. They clogged up quite a bit on us. When we can't get to our forecheck I think we can struggle a little bit. Having one or two shots about halfway through the game just isn't going to do it."