obsolesce . . . Many buildings are demolished early if their outdated systems are too deeply embedded to replace easily.
Space Plan: The interior layout—where walls, ceilings, floors, and doors go.
Stuff: Chairs, desks, phones, pictures . . . all the things that twitch around daily to monthly.
Imagine what each of these layers could represent when mapped to a particular product. To briefly illustrate this idea the following list uses the layers to examine the Apple iPod and iTunes product/service system mentioned earlier:
Site: computer integration, URL, sound
Structure: docking port, headphone jack, scroll wheel, screen
Skin: color, materials, headphones, graphical user interface
Services: cabling, disk dive, song formats, software architecture
Space Plan: navigational menus, song information, display windows
Even this quick analysis exposes how components in a product can be logically grouped by rate of change. Think about how this could be applied to other products—what is the Stuff layer of a microwave or the Services layer of a web site?
Each layer can change at a different rate but its speed is not completely divorced from the others, slower layers tend to constrain the faster ones. Brand describes, “How a room is heated depends on how it relates to the heating and cooling Services, which depend on the energy ef iciency of the Skin, which depends on the constraints of the Structure.