This thesis aims to discuss ways of opening up the design brief when designing for extreme environments such as intensive care units and remand prisons. Focusing on “designials” (fundamental forms of design being), the methodology intends to illustrate the fact that objects may directly impinge upon certain “existentials” (fundamental forms of human being). Moreover, the method is a form of critical design that enables designers to shift focus, from analysis of the functionality of a design in use, e.g. by performing a functional analysis, to analysis of the form of being human that a design in use defines. More importantly, this thesis considers what may happen if we do not take into account this aspect of design; in other words, the “dark side” of design thinking.