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Monday, December 19, 2011

Design Specifications & Shelter Intensity

***Please see my latest book, The Science of City Design: Architectural Algorithms for City Planning and Design Leadership, on in both e-book and paperback versions.***

NOTE: This essay has been rewritten in 2017 under the title, "Comparing Shelter Design Decisions" to correspond with the updated format and equations in the book referenced above.
Within the Shelter Division of the Built Environment, design specification values define intensity. This is the relationship of project open space to gross building and pavement area per buildable acre available. When design specification values are entered in the template of a forecast model, embedded equations use these values to predict a site plan intensity option. When one or more specification values are changed in a forecast model, it predicts a revised option, but unrestrained values can produce excessive intensity. From this perspective, design specification values represent the DNA of shelter, but it is not a gift with the natural power of adaptation. It is our responsibility.  

Development Capacity Evaluation v.2 is a software collection of forecast models attached to Land Development Calculations, 2.ed. (LDC). They predict the site plan intensity implications of values entered in their design specification templates, and the results have larger Built Environment implications as well. When these templates are related to land use plans, they represent a city design for activity, intensity and urban form. This gives us the potential to achieve physical, social and economic objectives within the sustainable limits of a Built Domain.  

Generic site plan options fall into two land use families and are distinguished by their method of providing parking. Table 1 lists some of the decisions that lead to a forecast model. The complete set of decision trees is presented in “Improving the Argument for Architecture and City Design”. Each forecast is a function of the model chosen, the core area available (See Diagram 1) and the design specification values entered in its template.  

Core area is simply the land remaining for building cover (footprint) and parking cover after a project open space percentage is subtracted from the buildable land area available. Buildable land is the land remaining after unbuildable areas and public right-of-way dedications are subtracted from the gross land area available. 

Forecast models predict gross building and parking area potential per buildable acre based on the values entered. The intensity predicted indicates shelter capacity and activity for a given land area, but it can be overdone. Since design specification values define intensity, they represent the instructions required to shelter activities within the Built Environment. There are an infinite number of potential value combinations, however. Existing context evaluation will be required to appraise values and select options to produce a restricted Built Domain that protects its source of life – The Natural Domain.
Figures 1-4 are photographs of two projects based on the CG1L forecast model, but with different design specification values. The model pertains to non-residential land use activities (C) that use a grade parking lot around but not under the building (G1) when the gross land area (L) is given. This model includes a project open space allocation (S) and a parking space allocation (s) in its design specification template. Both provisions make open space a conscious decision rather than an afterthought assembled from left-over land. 

Fig 1 Office Project Aerial View

Fig 2 Office Project Parking Lot

Fig 3 Corporate Office Aerial View

Fig 4 Corporate Office Entrance

The green open space in Figures 1 and 2 is a rather typical quantity found in office projects around the globe, and is more generous than many. The green open space in Figures 3 and 4 is part of a corporate office park that is not typical, but present in many communities. 

The two projects do not look the same, but they share the same design specification template. The difference is represented by the values entered and the appearance applied. When appearance is ignored, the geometry is called building mass, or “massing”, and the relationship of mass and pavement to project open space is called intensity. Intensity can be measured and is defined by the contrasting values in Table 2. The values (s), (a) and (S) are indicators of the differences beneath appearance. 


The design specification values in Table 3 define the project in Figure 1. The planning forecast table at the bottom of this table also displays the options that were available if greater building height had been considered. Table 4 defines the project in Figure 3 and also displays the options that were available. Both tables are based on the forecast model CG1L, and a change in any design specification value would produce a new forecast of options. These value categories are the DNA of CG1L design. Value decisions represent DNA instructions that can lead shelter construction toward the goals of a Built Environment within the limits of a Built Domain. 

The parking lot areas shown in Figures 2 and 3 are often expanded to increase development capacity at the expense of project open space. Their internal parking open space may also be compressed to increase the number of spaces provided. This increases gross building area per buildable acre, or intensity, but decreases the project’s contribution to a city’s physical, social and psychological quality of life. Its economic contribution over time also comes into question when the building is placed in the middle of an asphalt parking lot, since it will rarely attract employment centers with the greatest revenue potential and appears to have a greater tendency to deteriorate.  

When a low value for (s) is entered in a design specification template, the forecast provides less area per parking space and must use it all for pavement. Higher values include internal area for landscape improvement to reduce parking intensity. The parking lot open space implied by the total value (s) combines with the project open space (S) specified to determine the relationship of people to the building and parking intensity created. (See "Parking Lot Design Implications”) This open space combines with the Open Space Division of the Built Environment and the expansion area of the Built Domain to define the fabric of a city and its weave into the Natural Domain of its host.  

The photographs and statistics for Fig 3 reveal another parking lot option however. The value (s) is low indicating that only pavement has been provided for the parking lot, but every parking bay is separated by a project open space finger that reduces the collective intensity of parking and provides a separate pedestrian route to the building entry for every parking space. Therefore, the area allocated per parking space (s) combines with the project allocation (S) in this design to reduce parking intensity, since ultimate intensity produces a sea of asphalt that has too often been considered an adequate substitute for project open space. 

This is the dilemma in a nutshell. More open space means less shelter capacity given the same building height and parking requirements, but we have not been able to predict the options available; and when you cannot predict you cannot anticipate nor plan for coexistence that protects our sustainable future. Design specification values are at the heart of the shelter issue. They are virtually unregulated, however, because independent zoning requirements do not anticipate the implications of interaction. The equations of Development Capacity Evaluation v.2 have been written to define this interaction, but context research and analysis is needed to define value limits that will offer lifestyle options while protecting our health, safety and quality of life. Context research therefore represents the potential to distill urban DNA to treat unsustainable growth on the face of a gift we cannot replace. 


The Natural Domain is at risk from our Built Environment. This domain is being threatened by site plans that multiply without the restraint of Built Domain limits; but if there were limits, internal growth of the Built Environment could not be guided by zoning regulations that are unequal to the DNA required. They are simply hurdles in the path of sprawl.

The Built Environment contains Movement, Open Space and Life Support Divisions that serve a Shelter Division. A site plan for shelter construction is the city design equivalent of cellular growth within this environment. Site plans in the Shelter Division contain various degrees of open space within their project limits, but shelter is the primary objective. The Open Space Division within the Built Environment contains, but is not limited to, agriculture and parks. Environmental open space is a separate Natural Domain. In other words, the Built and Natural Domains depend on open space because it is their common foundation for survival. From our standpoint, open space within the Built Environment, the Built Domain and the Natural Domain protects us from oppressive cities and an unsustainable future.  

The term “Built Domain” means the entire area available for the Built Environment. The Built Environment is an organism evolving within the Built Domain. At the present time there is no meaningful distinction between the Built Domain and the Natural Domain.  

The entire classification system for the Built Domain can be found in Appendix A of Land Development Calculations, second edition, published by The McGraw-Hill Companies, 2010. The Open Space Division is meant to include undeveloped expansion areas within the limits of a Built Domain, but these areas must be distinguished from agricultural areas to be preserved and a Natural Domain to be protected.  

Open space in the Built Environment is at risk from overdevelopment. Open space in the Built Domain is at risk from annexation and speculation. Open space in the Natural Domain is at risk from sprawl that continues to consume the face of the planet.  

It’s easy to imagine a separation of domains that protects the planet’s ecological and environmental systems, but more difficult to imagine a Built Domain that can shelter population growth within limits that are physically, socially, psychologically and economically sustainable. The devil is truly in the detail of design decisions, since they must lead to the birth of a symbiotic future.  

In science, coexistence is a symbiotic state we are attempting to enter with environmental awareness. There are many facets, but the sprawl of our Built Environment is an underlying threat unchecked by city plans focused on internal risk from land use conflict and building construction. The sprawling result has now expanded to threaten a Natural Domain that does not compromise with ignorance. 

There are two fundamental questions: (1) what are sustainable limits for the Built Domain and (2) what are the physical, social and economic relationships within a Built Environment that can shelter population growth while protecting its health, safety and welfare?  

DNA is a frame of reference. In the world of Biology it is a leadership plan, a set of instructions and a measurement system that defines physical limits, operational responsibilities and functional relationships, but these definitions have been a gift at birth. It is our responsibility to define a similar plan for the organism we create within a Built Domain that will not threaten its natural host. At the present time, the physical limits of the Built Domain are unrestrained; and healthy relationships with the Natural Domain are as mysterious as anatomical relationships in the Middle Ages. We now have satellite images of urban anatomy on the examining table, but the patient is alive and we are staring at growth that is out of control with an inadequate regulatory system.  

Sustainable geographic limits for the Built Domain can only be defined by the science of many cooperating disciplines. Some geographic issues are obvious, however. For instance, building over jungles, forests, swamps, fault lines, wetlands and flood plains, below sea level and on the beach is not sustainable; nor is the continuous consumption of agriculture for shelter, the obstruction of migration paths, the disruption of spawning patterns and the diversion of rivers and streams -- not to mention pollution, resource depletion and energy consumption. Looking at each of these issues separately is scientifically essential because detailed information is required, but failing to treat them as overlays to reveal the land remaining for our Built Domain is an unsustainable habit. In the end, design is required, and it is the ability to imagine the forest after memorizing the trees on a tortured path of discovery.

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