Reyner Banham’s introduction to The Architecture of the Well-Tempered Environment is a polemical correction to architectural history’s most persistent blind spot: its privileging of visible form over the invisible systems that make buildings habitable. Banham argues that architecture became intellectually impoverished when it separated “architecture” from “technology”, relegating heating, ventilation, lighting, sanitation and environmental comfort to engineers, plumbers and consultants rather than recognising them as central to architectural practice. His critique is not anti-technology; it is anti-amnesia. Conventional history could absorb iron, steel and concrete because they extended familiar narratives of structure, but mechanical ventilation or electric lighting disrupted the discipline’s aesthetic habits. The case of Louis Kahn’s Richards Memorial Laboratories and Frank Lloyd Wright’s Larkin Building, illustrated in the introductory pages, shows how historians noticed service towers or ducts only when they produced a monumental exterior effect, while largely ignoring the deeper transformation of occupation, comfort and environmental control. Banham’s method therefore replaces the cult of the “first” invention with the study of typical buildings in which technologies became architecturally consequential. This position remains crucial in an age of energy anxiety: sustainable architecture cannot mean nostalgic retreat into masonry, nor uncritical dependence on machines, but a rigorous rethinking of environmental performance as architectural substance. Banham’s conclusion is uncompromising: those who shaped comfort, climate and servicing belong inside architectural history because they helped define the practice of architecture itself.