I am enrolled in an online permaculture course where the goal is to achieve a permaculture design certificate at the end of 1 year or sooner depending on how much I want to study. An important permaculture idea that I want to focus on today is the idea of "stacking functions". I think this idea is generally useful to know about so will be sharing some of my research.

One of the permaculture books I consulted is Gaia's Garden: A Guide to Home-Scale Permaculture (2009), 2nd Edition, by Toby Hemenway.

Hemenway introduces the concept of "stacking functions" by way of a home gardening example:

...every part of the garden does more than just one thing. Permaculture designers have a bit of a jargon to describe this. They call it "stacking functions". Nothing in nature has only one function; it is furiously efficient in this way. A shrub, for example, doesn't just cast shade. It feeds winter-staved birds with its berries, offers shelter, mulches the soil with its leaves, provides browse for hungry deer and porcupines, blocks the wind, holds the soil with its roots, collects and channels rainwater, and on and on.

Nature always stacks functions, because that shrub, or any living thing, represents a big investment in matter and energy, two things that nature husbands with immense stinginess. Nature is supremely skilled at getting the most bang for the buck, squeezing every erg of energy out of that shrub, tying it into lots of other cycles to maximize the return... By making plants perform multiple functions, nature users her energy investment very efficiently. (p. 33)

.... The two aspects of function stacking - each element performs multiple functions, and each function is served by multiple elements - can be used throughout the garden, on many levels, to align the landscape with nature's might. (p. 35)

Ben Falk, in his permaculture book, The Resilient Farm and Homestead (2013), uses a nice down-home wood cookstove example to convey the idea of "stacking functions":

Ben has this to say about how his wood cookstove stacks functions:

The homestead's most important power plant is our wood cookstove. It is pictured here in typical midwinter action performing multiple functions simultaneously: boiling tea water; cooking a multiday meal of venison, lamb, squash, potato, seaweed, shiitake, sunflower seed, kales, and garlic; boiling gone-by squash for the ducks; baking cookies; simmering chage-reishi chai for desert; heating all the hot water needed by two people for bathing and dishes; and heating fifteen-hundred square feet of space to 72F on a 20F day. (p. 220)

Gloves appear in the drying rack so I would add "drying out clothes" to the list of functions that Ben's wood cookstove provides. Ben's stove is not just functionally stacked, it is literally stacked with objects that carry out the different functions through their relationship with his "power plant".

These are good examples to use to grasp the concept of "stacking functions", however, it is interesting to note that Bill Mollison, in the primary text for the field of permaculture, Permaculture: A Designer's Manual (1988), does not appear to use the jargon of "stacking functions" explicitly in "Chapter 3: Methods of Design" where much of his discussion on the importance of functional design first takes place (it is also not listed in the book's index as such). Perhaps the "stacking" metaphor puts too much focus on the object attributes rather than the relationship between object attributes. This is what Bill has to say at the beginning of chapter 3:

3.1 INTRODUCTION

Any design is composed of concepts, materials, techniques, and strategies, as our bodies are composed of brain, bone, blood, muscles, and organs, and when completed functions as a whole assembly, with a unified purpose. As in the body, the parts function in relation to each other. Permaculture, as a design system, attempts to integrate fabricated, natural, spatial, temporal, social, and ethical parts (components) to achieve a whole. To do so, it concentrates not on the components themselves, but on the relationship between them and on how they function to assist each other. For example, we can arrange any set of parts and design a system which may be self-destructive or which needs energy support. But by using the same parts in a different way, we can equally well create an harmonious system which nourishes life. It is in the arrangement of parts that design has its being and function, and it is the adoption of a purpose which decides the direction of the design.

Definition of Permaculture Design

Permaculture design is a system of assembling conceptual, material, and strategic components in a pattern which functions to benefit life in all its forms. It seeks to provide a sustainable and secure place for living things on this earth.

Functional design sets out to achieve specific ends, and the prime directive for function is:

Every component of a design should function in many ways. Every essential function should be supported by many components. (p. 36)

I'll end my permaculture study today with this. Hope you find this discussion of stacking functions useful in thinking about what good design might consist of.