Which term is associated with enhancing a facility's existing equipment to perform differently?

The term that best fits the description of enhancing a facility's existing equipment to perform differently is "upgrade." An upgrade typically involves improving or enhancing the functionality or performance of existing equipment or systems, making them more efficient or providing new features. This can involve integrating new technology, adding components, or improving software to enhance overall performance.

Modification generally refers to a change made to adapt or fit something to new conditions but does not specifically imply improving performance. Alteration usually indicates a change in appearance or structure that may not directly relate to enhancing performance. Renovation is broader and often refers to restoring or improving an entire structure rather than just enhancing existing equipment. Thus, "upgrade" is the most accurate term for the enhancement of equipment in terms of performance or functionality.