1. A rooftop HVAC assembly comprising HVAC equipment and a screening system, the HVAC equipment being mounted operably on a roof of a building by a support that is a roof curb or set of equipment rails, wherein the screening system does not contact the roof of the building and is not attached to the roof curb or set of equipment rails but rather is attached to the HVAC equipment, the screening system being assembled operatively so as to surround the HVAC equipment, the screening system including a screen panel that is adjustable between a lower, closed position and an upper, open position by moving at least part of the screen panel selectively upwardly or downwardly, and the screen panel comprises a fabric screen formed of an opaque fabric that is substantially impervious to wind.