By Kenneth Hilario, Philadelphia Business Journal

The Philadelphia Convention & Visitors Bureau on Friday reported 2015 as its highest booking year ever with 856,663 room nights secured last year for future years, up 1.2 percent from the previous year.

The number of bookings are estimated to generate more than $1.1 billion in economic impact to the city and the region, according to PHLCVB.

About 75 percent of the room nights booked are related to meetings and conventions that will take place at the Pennsylvania Convention Center. The remaining room nights are related to meetings taking place at regional hotels and other venues.

Antiquated work rules at the Convention Center held back the city's growth in the convention circle because major groups had been canceling their annual meetings from Philadelphia or avoiding the city altogether.

Only in May 2014 did things start to turn around when new work rules were put in place, signed by four of the Convention Center's six labor unions.

The new work rules, according to meeting planners, were more cost-effective, streamlined and friendly.

Since the new work rules were put in place, several groups that previously canceled, changed course and rebooked the center. Most recently Lightfair International, which will come back in 2017, decided on the Convention Center.

About 69 percent of the future conventions that were secured last year are returning customers, according to PHLCVB, including the Biotechnology Industry Organization, or BIO, which will generate more than $41 million in economic impact.

The 69-percent figure is up from 45 percent in fiscal year 2013, the last full-booking year before changes were implemented, according to PHLCVB.

This year, the PHLCVB has 275 meetings and conventions booked from Jan. 1 to Dec. 31.

Those meetings and conventions will consume 552,269 total room nights, generating more than $730 million in economic impact for Philadelphia, according to PHLCVB.