LEARNING TO LEAD SHELTER CAPACITY DESIGN DECISIONS

 The G1 Building Design Category includes all buildings with a surface parking lot adjacent to, but not under, a building on the same premises. The maximum gross building area that can be provided to shelter permitted activity is a function of the core land area remaining for parking cover and building cover after all other demands and/or land deficiencies are subtracted from the gross land area given.

When the core area is multiplied by the coefficient in parentheses in Equation (1), the result is a maximum gross building area forecast (GBA) that increases with the floor quantity considered. The equation for this G1 shelter capacity relationship is:

Equation (1):

G1 Building Design Category 

GBA = ((a/f) / (a + (fs))) * CORE

 When: 

GBA = gross building area

a = total parking lot area per parking space in sq. ft.

f = floor quantity

s = parking lot area per parking space in square feet

CORE = land area remaining in square feet for parking cover and building cover after all other demands and/or land deficiencies are subtracted from the gross land area given. 

The values (a), (f), and (s) in Equation (1) are variable design decisions. The importance of accurately defining the core area available for use in this equation is imperative and will be discussed.

The forecast model for Equation (1) is included as Table 1. Lines 3-33 are devoted to the derivation of the core area (CORE) remaining in cells F33 and G33 for parking cover and building cover after all other demands and/or land deficiencies are subtracted from the gross land area given. This includes the percentage of unpaved open space (S) to be subtracted from the buildable land area in cell F11. It is a critical decision because it offsets the amount of building cover, parking, and pavement (impervious cover) that produces storm water runoff; and that must be accommodated by the storm sewer capacity planned or present. It is also a critical factor contributing to the amount of physical intensity introduced to a given land area. These Table 1 decisions produce the shelter capacity, intensity, intrusion, and context implications calculated in cells F44-J53.

Table 1 has been discussed many times. It is used to find the G1 shelter capacity of land based on the design specification variables entered in the shaded cells of its G1.L1 forecast model. It has been customized for this example by entering one acre in cell F3 and zero in all other shaded cells except F3, F11, A35, A36 and A44-A53. The combination represents a land area unencumbered by land deficiencies and miscellaneous pavement provisions.

In other words, the core land area (CORE) found in cell F33 is equal to the gross land area given minus the unpaved open space quantity specified in cell F11. This is the greatest the core area can be, unless the unpaved open space percentage entered in cell F11 is reduced.

The values entered for (s), (f), and (a) in cells A35, A36, and A44-A53 are needed to calculate the coefficient in parentheses in Equation (1). A change to one or more of the values entered changes the coefficient and the gross building area options calculated. Since no miscellaneous pavement area percentages are subtracted, the gross building area predictions in cells B44-B53 are maximum forecasts based on the values entered and the core area defined.

The point is that G1 shelter capacity on a given land area is the product of its core area multiplied by a coefficient that is formed from three design decisions. When a gross land area of one acre is given and an unpaved open space percentage is subtracted from the buildable land area to find the core area remaining, the coefficient indicates the percentage of the core area that will equal the gross building area capacity of any given land area when considering the G1 building design category. Table 2 has been created to illustrate the point along with a few observations below. Be careful to note in this example that the core area example is equal to the one acre given minus the unpaved open space percentage noted with each schedule of the table.

The values entered in the gray cells of Table 2 indicate given information. The coefficients calculated in the white cells of each schedule in the table indicate the fraction of any core land area that can become G1 gross building area given the conditions chosen to identify the coefficient multiplier at their intersection. Obviously, the accurate definition of core area for use with the coefficients in each schedule is critical, and the temptation to reduce unpaved open space (S), increase the gross building area planned or permitted per parking space (s), and increase the floor quantity (f) under consideration will increase potential gross building area. The temptation to overlook unbuildable, unstable, environmental, historic, archeological, woodland, water, public roadway, wetland areas and so on can also increase since their subtraction reduces the core area available for building footprint area. However, considering any of these areas as part of the core area available represents an attempt to artificially inflate the shelter capacity of a given land area. The increasing intensity and intrusion calculations that result would represent a decline in the context anticipated.

Keep in mind that Table 2 is meant to display maximum possibilities based on a core area that has no miscellaneous pavement percentage estimate subtracted. It has been omitted because it cannot be consistently predicted, but an estimate should be subtracted from the core area available before gross building area prediction when a specific project makes a more accurate forecast possible.

Table 3 has been included to illustrate the increase in gross building area percentages of core area (coefficients) that occur when the incremental unpaved open space allocation declines from 40% to 20%.

A comparison of the coefficients in Tables 2 and 3 should illustrate a very limited picture of the tug-of-war that has occurred between architects, planners, urban designers and real estate interests when the shelter capacity, intensity, intrusion, and context implications of design specification decisions could not be measured, predicted, and evaluated on a uniform scale for comparison, and leadership direction. Equation (1) has made it possible to find common ground.

Tables 2 and 3 are a very small window into the spectrum of shelter capacity decisions that can lead us to shelter the activities of growing populations on geographic areas scientifically limited to protect their quality and source of life. I have written “The Equations of Urban Design” to crack the window for those who may be interested in pursuing the measurement, evaluation, knowledge, and decisions required to lead us in a direction that will respect the planet’s unwritten Law of Limits. Opinion without measurement and evaluation on a consistent, comparable physical scale of shelter capacity evaluation will not get us there.

Walter M. Hosack, June 2025

PS: Density is a social measurement that has attempted to lead physical decisions without the comprehensive shelter capacity specifications and mathematical correlation required. This essay has attempted to offer a glimpse of the building design categories, design specifications, algorithms, master equations, and implication predictions involved with urban design decisions and discussed in detail in the book just mentioned. I am leaving research, measurement, evaluation, knowledge acquisition, and leadership decisions to those interested in applying the vocabulary and language provided.