Allometry and built form: revisiting Ranko Bon's work with the Harvard Philomorphs

Ranko Bon's Master's thesis at Harvard was devoted to the phenomenon of allometry in the forms of buildings. The concept of allometry comes from biology, and refers to changes in the forms of organisms as they alter in size. For example the ratio of volume to surface exposed to the air (including the lungs) is of great functional importance to animals, and tends to remain constant as they get larger. Bon studied allometry in residential buildings, and showed that both the ratio of surface to volume and the ratio of circulation length to floor area were preserved over a wide range of building sizes. Bon's work is revisited from a theoretical point of view, using a new method for representing large numbers of theoretical but realistic built forms, all derived from a single 'archetypal building'. By choosing default dimensions typical of dwellings, Bon's original results can be reproduced. By varying these dimensions of plan depth, numbers of storeys and widths of courts or light-wells, it is possible to show what precise kinds of allometric relationships are likely to be found in other types of day-lit buildings besides dwellings.