3M's Embarcadero Center case study is the number worth knowing: 345,000 square feet of solar control film, paid back in under twelve months through reduced cooling load. It's a big-tower example, but the mechanism scales down without changing.
Cooling cost isn't driven by average temperature, it's driven by peak load. West and south glass dumps its heaviest solar gain into the building in the same afternoon hours your chiller is already working hardest. Flattening that spike is worth more per dollar than almost any other envelope improvement you can make without touching the structure.
There's a comfort argument too, and it's the one tenants actually complain about. Window-side desks cook while interior offices sit cold, so somebody drops the thermostat and now you're overcooling the whole floor to make one row of desks bearable. Film narrows that spread.
Add 99.9% UV rejection and the merchandising benefit shows up on its own: menus, packaging, upholstery and signage in a display window stop bleaching out.