The search for a scale that can measure the level of
pressure imposed by shelter, movement, open space, and life support within the projects,
neighborhoods, and districts of our urban world continues. I believe this human
scale has at least five measureable components; and that they combine to give
an initial indication of urban health within the urban anatomy. These factors
and terms are relatively unknown, so let me begin with an explanation.
CAPACITY
Shelter capacity (SFAC) is the gross building area (GBA) in
sq. ft. provided per buildable acre (BAC) to shelter any activity. We tend to
refer to buildings by the activity within, such as a bank building; but a
building can be remodeled to suit many activities. The significance of the
building is the amount of land it consumes per thousand sq. ft. of gross building
area, since this is land removed as a source of life.
SFAC = GBA / BAC
INTENSITY
Building capacity is a measureable factor that can be
multiplied by a surface pavement percentage to produce an intensity measurement,
but the impact of the measurement must be evaluated in addition to three other
factors that combine to affect our physical, social, psychological,
environmental, and economic quality of life. Like the first blood pressure
readings, however, these measurements will have little meaning until evaluated correlated
within a database of accumulated research.
Shelter capacity produces building mass. In this context,
the first sentence in this section can be rewritten to say that the product of
building mass times the percentage of impervious pavement present in a
buildable land area is a measurement of physical intensity. Building mass is
represented in this context by a massing ratio equal to shelter capacity per
acre (SFAC) divided by one acre in sq. ft. to make the calculation a manageable
statistic. In mathematical terms:
MAR = SFAC / 43,560
INT = MAR * IMP%
The Theory of
Relative Intensity
A range of potential building mass values has been placed along
the y-axis of Table 1, but the ratios do not indicate the impact of related
two-dimensional pavement. Impervious cover ratios are represented in ten
percent increments of buildable land area along the x-axis to complete the matrix.
When an impervious cover percentage is multiplied by a massing ratio, the
result is a level of intensity within a given buildable land area (BLA). Table
1 presents the entire range of shelter intensity options available to planners,
architects, and designers in a single table. The fact that a value is in the
upper left hand quadrant of Table 1 does not automatically mean that it is
desirable, however. Table 1 simply defines the entire spectrum, and many
options are undesirable. The challenge is to measure, evaluate, identify, and
locate existing success and failure within the table.
Shelter capacity is produced by six shelter design
categories that can be occupied by any permitted activity. These categories
comprise the Shelter Division of The Built Domain and are listed Table 2. Three
examples of the residential activity group are shown below these design
categories to illustrate the relationship between a design category and an
activity group. The classification illustrated is part of the language needed
to pursue the science of city design, and begins with the recognition that
there are two worlds on a single planet: The Natural Domain and a Built Domain
that contains Shelter, Movement, Open Space, and Life Support Divisions.
Informed annexation and land use allocation can only occur
when there is a mathematical ability to correlate the shelter capacity options
for land with the economic yield implied by potential activity per buildable
acre. When correlation becomes feasible, land use allocation, capacity, and
intensity options for economic security will become a subject of digital
planning and evaluation. The knowledge gained will give planners the
credibility to persuasively debate the issue and pursue new revenue that is not
based on old assumptions, opinions, and mistakes.
INTRUSION
Intrusion (INTR) is a calculated value used in a building
dominance calculation (DOM). It is building height in floors (f) divided by
five to avoid the unwieldy calculations produced by skyscraper heights. (When
there are two or more buildings in the same project area, varying heights must
be weighted to reflect the composition.) Intrusion is introduced as a
calculation because a taller building is considered to be more intrusive when
all other site planning topic values are equal.
DOMINANCE
Shelter dominance (DOM) is the sum of shelter intensity
(INT) and intrusion (INTR) within a project, neighborhood, or district. In
mathematical terms:
DOM = INT + INTR
When the constituent topics of intensity and intrusion
equations are substituted in the dominance equation above, it becomes:
DOM = ((SFAC / 43,560) * IMP%) + (f/5)
In more general terms, shelter dominance within a project,
neighborhood, or district land area is a function of: (1) the buildable land
area available; (2) the gross building area constructed; (3) the percentage of
buildable land area occupied by impervious cover; and (4) the building height
introduced.
Table 3 has been created to illustrate the spectrum of
potential building dominance options. Intensity options are arranged along the
y-axis and intrusion options are arranged along the x-axis. Adding the two
options produces a matrix of dominance values that represent the spectrum of
design options available, and not all are desirable. The challenge is the same
as that presented by the intensity matrix in Table 1. Existing success and
failure must be measured, evaluated, identified, and located in the table.
IMPACT
Impact is the correlation of traffic with shelter dominance in
an urban area. A traffic ratio (TRR) is equal to the average daily traffic (ADT)
in a neighborhood block divided by 1,000 to make the statistic manageable. Impact
is measured by adding a shelter dominance measurement to a traffic movement
statistic. In mathematical terms:
TRR = ADT / 1,000
IMPACT = DOM + TRR
IMPACT = ((SFAC / 43,560) * IMP%) + (f/5) + (ADT/1,000)
In other words, if you can calculate shelter capacity and
impervious cover, you can calculate the shelter intensity present on a given
buildable land area. If you know intensity and building height, you can
calculate building dominance. If you have calculated building dominance and know
the average daily traffic present or predicted adjacent to the land area, you
can calculate physical impact. (A larger number indicates greater impact.)
An impact measurement includes capacity, intensity,
intrusion, dominance, and movement statistics. The spectrum of possibilities
represents a graduated human scale that can indicate the health of an urban
area in relation to the surrounding activity present. The actual spectrum raises
a fundamental question for further research:
What impact limits are
needed to protect our physical, social, psychological, environmental, and
economic quality of life within a geographically limited Built Domain that is
economically stable and ecologically symbiotic?
Answers to this question will begin to define the context,
composition, pattern, and appearance required to protect a growing population’s
source and quality of life. Answers must be found because Mother Nature simply
does not compromise with ignorance.
POTENTIAL
The decisions we make concerning the shelter capacity of
land is a first tier consideration. It affects the composition, context, and
capacity of the cities we inhabit and the scope of land removed from its
symbiotic purpose. The activity that takes place within shelter capacity, and
the surrounding relationship of these activities, varies as building occupancy
changes. This physical and social equation adjusts at a very slow pace, but we
have enough experience to know that they can affect a city’s psychological,
environmental, and economic vitality when they cannot be forecast to prevent a
declining quality of life.
Up to this point the discussion has focused on the
measurement of existing conditions. The objective, however, is to learn from
these conditions; to repeat success; and to avoid failure. This means that we
must be able to use the knowledge gained to lead future policy, strategy,
tactics, and performance. Table 4 is included to explain how this can be
accomplished using the G1 Design Category as an example.
The G1 Category includes all buildings with surface parking
around, but not under the building. It seems to be the most popular shelter
category in use today, and is occupied by a wide range of activities with an
equally wide range of economic potential. The purpose of this example is to
demonstrate how shelter capacity options for a given land area can be
accurately predicted. This forecasting potential is the key to strategic city
design evaluation and decisions that can be specified with the item values
adopted in a design category forecast model.
In other words, shelter category and capacity decisions come
first. They establish the composition and context of an urban pattern that must
be designed to protect our quality of life. Occupancy determines the economic
potential of the shelter resource provided.
Gross land area is given in cell F3 of Table 4 and shelter
capacity options (GBA) are predicted in Column B of the Planning Forecast Panel
based on the building height alternatives in Column A. The values entered in
the boxes of the table represent the design decisions that were correlated to
produce the forecast. This template should make it clear that a single value
cannot hope to lead to the results predicted.
A change to any value in any box of the template would
produce a new forecast. The values predicted in Columns C-G of the Planning
Forecast Panel are functions of the shelter capacity predictions in Column B.
They are a small sampling to the predictions that can be made once the shelter
capacity options in Column B can be forecast. For instance, construction cost,
population, traffic generation, and the economic implications of occupant
activity are just a few of the predictions that are a function of the square
foot options forecast in Column B of the Planning Forecast Panel.
The values entered in the template specification boxes of
Table 4 represent a definition of human scale. There are 15 specification boxes
and 10 building height alternatives that can be evaluated for a total of 25
optional design decisions. Measured values from an existing project could also
be entered in these boxes for evaluation. The intensity levels calculated in
Column G of the Planning Forecast Panel present the implications associated
with these decisions. They are like blood pressure readings without a frame of
reference, however. The condition of the patient cannot be placed in perspective.
At the present time Table 4 represents potential. It is not
an answer but part of a vocabulary and language that can be used to search for
graduated levels within a human scale that will protect our quality and source
of life. I won’t discuss Table 4 and its design category companions in greater
detail because they are covered in my new book, The Science of City Design.
It is available in e-book and paperback from Amazon.com. The book is my attempt
to expose the potential to define human scale in terms that can define past
decisions and lead to a symbiotic future.
THE SYMBIOTIC
IMPERATIVE
When the architect Louis Sullivan mentioned that form
follows function he was actually referring to a fundamental organic principle,
in my opinion. His student, Frank Lloyd Wright, adopted the concept and
referred to “organic architecture”. I believe they were both pointing to a
symbiotic imperative that they could only express at the time with fine art. I’ll
repeat Sullivan’s poem here and let you draw your own conclusions.
"It is the
pervading law of all things organic, and inorganic,
of all things
physical and metaphysical,
of all things human
and all things super-human,
of all true
manifestations of the head, of the heart, of the soul, that the life is
recognizable in its expression,
that form ever
follows function. This is the law."
Louis Sullivan, 1896
The phrase “form follows function” was interpreted during
the Industrial Period to mean that the function of an invention is reflected by
its form and appearance, but this led us to overlook the symbiotic imperative that
rules our presence on the planet. It would not have been so easy to overlook if
the last line in Sullivan’s poem had read, “that
form ever follows (symbiotic) function. This is the law.” We began
converting and consuming the land with our inventions, and recognized that the
forms and objects we created were a function of the purpose we defined. It was
easy to assume that we took precedence over the symbiotic imperative until ecological
failure began to appear.
We will not correlate our presence on the planet with its
symbiotic imperative overnight, but I believe most of us recognize that we cannot
consume the planet with a blanket of sprawling pavement, or co-opt its natural
functions, and survive. The form of shelter capacity, intensity, and dominance
is one issue. It affects our ability to live within a limited Built Domain that
protects our quality and source of life – The Natural Domain. The symbiotic
function of The Built Domain is a separate issue. Both must be solved. There is
no option. This is what Sullivan meant when he said, “This is the law”. Cities
will not flower until they build symbiotic roots. The human scale is a
contribution to the growing number of tools that can be used to build knowledge
and lead city design toward the goal.
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