This thesis aims to discuss ways to open up the brief in designing for extreme environments, such as intensive care units and remand prison. Focusing on „designials‟ (fundamental forms of design being), the methodology intends to illustrate that things; objects may directly impinge on certain „existentials‟ (fundamental forms of human being). Moreover, the method is a form of critical design enabling designers to shift focus from “analysing the functionality of a design in use” (Torkildsby 2012, p. 18), e.g. by performing a functional analysis, to “analysing the form of being human that a design in use defines” (Ibid), and more importantly, what may happen if we do not – thus the “dark side” of design thinking. Here I am outlining the existential designial analysis in a design manual and further discussing, through the context of a fictive dialogue, How, Why and When it can be applied to the design of these environments.