Open Space Metrics

“Can the lessons of European squares be translated into metrics?”

Pete Pointer

Metrics will evolve from the measurement, comparison, and evaluation of many existing conditions when a consistent method of calculation is adopted. In my opinion, measurement must take the two and three-dimensional characteristics of any study area into account. I suggest that we look beneath appearance to begin with, and measure a project area in acres that includes the buildings surrounding the space. The entire set of measurements would include:

Total project area in sq. ft. and acres: TPA

Total building cover in sq. ft. and acres: BCA

Gross building area in sq. ft. and acres: GBA

Social pavement area in sq. ft. and acres: SOPA

Service pavement area in sq. ft. and acres: SEPA

Unpaved social open space in sq. ft. and acres: UPA

NOTE: In order to find gross building area around the piazza, all buildings would first be converted to building mass. (Mass is an imaginary envelope that encompasses all architectural detail.) Mass would be divided into horizontal slices at 12 foot or 3.658 meter vertical intervals. The area in each of these slices would be added to find gross building area. This includes the campanile.

The following calculations would be based on the previous measurements (SF=sq. ft.; AC=acres):

Shelter capacity SFAC = GBASF / TPAC

Shelter capacity percentage SFAC% = GBAC / TPAC

Impervious cover percentage IMP% = (BCAC + SOPAC + SEPAC) / TPAC

Intensity% = (GBAC + SEPAC) / TPAC

The intensity percentage suggested above is a simplified version of the universal intensity calculation I have suggested in my book. The formula for this intensity index is:

INT = SFAC * IMP% / 10,000

The equation says that the shelter intensity present in a project area, and imposed on a surrounding area, is equal to the shelter capacity in the project area times the impervious pavement percentage planned or present divided by 10,000. The use of 10,000 is introduced to make the universe of intensity options manageable and presentable in a single table of relative intensity. This table is included as Table 1.

Walter M. Hosack, March, 2018