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Monday, December 19, 2011

Predicting Shelter Options within a Limited Built Domain

The capacity of land to shelter human activity is a function of its core area. The core area is hidden in plain sight and makes it possible to forecast hundreds of intensity options in the time it takes to sketch one. (See Fig 1) This is relevant because we must learn to predict and evaluate shelter options for growing populations within a limited Built Domain that does not threaten its source of life – The Natural Domain. 

Core land area equals the land remaining for building and parking after open space, unbuildable areas, rights-of-way, loading areas and miscellaneous pavement are subtracted from the gross land area GLA available as shown in Figure 1. Table 1 explains the arithmetic implied by Figure 1. Five gross acres is given. Ten percent of this area is estimated for rights-of-way and pavement, thus reducing the GLA to a net land area NLA of 4.5 acres. A further 20% of the GLA is subtracted for an unbuildable marsh, thus reducing the GLA to 3.5 buildable acres BLA. Arrows 1-6 in Table 1 point to values that further reduce BLA to determine the core area remaining CORE for development. Arrow 3 points to a 30% project open space provision that offsets building mass and pavement within the BLA. Arrow 8 points out that 64.3% of the BLA remains for development and Arrow 9 points out that this is 45% of the GLA purchased. In both cases the column to the right of Arrows 8 and 9 notes that 98,099 sq ft of core development area CORE remains from the 5 acre (217,800 sq ft) gross land area purchased.

The Planning Forecast Panel of Table 1 explains the development potential of this core area based on the design concept represented. (In this case, the model represents a non-residential building using a grade parking lot around, but not under the building.) The FLR column lists building height options from 1-15 floors. The gross building area column GBA predicts the building area produced by increased building height. The GBA column shows that the biggest building area gain occurs when building height increases from 1 to 2 floors. The gain from 3-5 floors becomes increasingly less, and the gain from 5-15 floors is practically irrelevant.  

The BCA column (building cover area) explains how the floor plan shrinks as the parking lot area increases in the PLA column to serve increased building height and area. The parking space increase is shown in the NPS column. Intensity is expressed as gross building area per buildable acre SFAC available, and is compared to the more traditional but less accurate, and far more arbitrary, floor area ratio FAR.

If a developer is not satisfied with the gross building area forecasts calculated, his only option is to increase the core area by altering his design specification values, and open space S is often the first reduction. Any such design specification alteration could easily involve variance requests, but its implications are difficult to assess without development capacity evaluation. 

Our ability to shelter human activity within environmental limits depends on our ability to accurately predict development intensity options for every core area within these limits. It also means that we must understand the impact of these intensity options, since our history has proven that the potential spectrum has physical, social, psychological and economic consequences that can threaten the health, safety, and welfare of any population.  

Population growth continues to place the built environment in competition with its natural partner. The extent of its land consumption for growth is a function of the planning decisions made to satisfy our need for shelter, since the movement, open space, and life support divisions of the built environment respond to serve this catalyst. The core area of every shelter project answers this demand, and our ability to forecast development capacity options, evaluate intensity, and offer variety will determine our ability to coexist with a natural partner that tolerates our presence within limits. 

Architecture can be designed, remodeled or converted to shelter any activity. It must simply respect the building and zoning codes that pertain. It can also assume any appearance. The shelter it provides, however, is an element of survival. The amount that can be provided is a function of the core land available. When land use allocation is combined with a three-dimensional strategy for core area shelter capacity, the result will be city design that has a chance of achieving symbiotic success. The architecture and context that emerges will again stand in mute testimony to the level of awareness reached.

Portions of this article were excerpted and edited from Development Capacity Evaluation software attached to my book, Land Development Calculations, ed. 2, published by The McGraw-Hill Companies, 2010.

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