Pressurized Stairwells

What is the criteria that determines if a building will have a pressurized stairwell?  What about elevator shafts?

The smokeproof enclosure provisions apply to stair enclosures of buildings that serve stories where the floor's surface is located more than 75 feet above the lowest level of fire department vehicle access or more than 30 feet below the level of exit discharge. Both the Life Safety Code® and the International Building Code® have provisions that apply to smokeproof enclosures and pressurized stairways. In the Life Safety Code® check the applicable occupancy chapter first as well as section 7.2.3. Check section 1020.1.7 and 909.20 in the IBC.