When the global financial crisis brought the economy to a standstill, real estate moldered. The so-called built environment was already rife with functionally obsolete structures. But when a wide swath of buildings suddenly became financially distressed, strapped owners did not have the capital or available financing to invest in care and maintenance, let alone bring their edifices up to modern grade.

The financial expenditure that was available went mostly to class A core properties (those considered safe harbors by investors), while class B and C assets (particularly in secondary markets) aged away: no external cosmetic treatments; no internal rejuvenation.

The speed of functional obsolescence has increased in pace for some property types, depending on location and technological innovation brought to market. There are also changing logistical patterns as global trade evolves and the lines between retail and industrial formats are blurred by e-commerce.