Civil Engineering Reference
In-Depth Information
ADISA-constructions are easily separated into piles of identical components and materi-
als during demolition.
First principle: Separate layers
A building consists of several parallel layers (systems): interior, space plan, services,
structure, skin (cladding) and site (see Figure 1.3). The main structure lasts the lifetime of
the building - 50 years in Norway and Britain and closer to 35 in the USA (Duffy, 1990) -
while the space plan, services etc. are renewed at considerably shorter intervals. In mod-
ern buildings the different layers are often incorporated in a single structure. Initially this
may seem efficient, but the flow in the long-term cycles
will then block the short-term cycles, and short-term
cycles will demolish slower cycles via constant change. It
is, for example, normal to tear down buildings where
installations are integrated in the structure and difficult to
maintain.
Space plans can be so specialized and inflexible that,
for example, in central Tokyo modern office buildings
have an average life span of only 17 years, (Brand,
1994).
We are therefore looking for a smooth transition
between layers (systems), which should be technically
separated. They should also be available independently
at any given time. This is a fundamental principle for effi-
cient re-use of both whole buildings and single compo-
nents.
Second principle: Possibilities for disassembly within
each layer
Single components within each layer should be easy to
disassemble. Figure 1.4 shows three different princi-
ples for assembling a wall cladding at a corner. The
shading shows where the mechanical wear and tear is
greatest, from people, furniture, wind and weather. The
normal choice today is the first solution, (a), where all
parts are the same quality and permanently connected.
When the corner is torn down the whole structure fol-
lows with it. In many expensive public buildings, solu-
tion (b) is chosen. By increasing the quality of the most
worn area, the whole structure will have a longer life-
time. This is usually an expensive solution and makes
changes in the space plan difficult, unless the whole
structure is demolished. In solution (c), worn compo-
nents can easily be replaced separately. The used
component can then be re-used in another corner
where the aesthetics are less important, or it can be
sent directly to material- or energy-recycling.
Figure 1.4: Three principles for connecting
walls.
