A system for maintaining thermal separation between first and second adjacent rooms or spaces. The system includes a vestibule with at least a first compartment, and other embodiments may include two or more compartments, such that the vestibule provides a passageway between the first and second rooms. At least one blower draws air from the first room through an air intake, and back into the first room through an exhaust. The system further includes an exhaust port from the first compartment in fluid communication with the exhaust, to exhaust air from the first compartment into the first room. During operation, a vacuum is formed within the first compartment that provides thermal separation between the first and second adjacent rooms.