Giraffe works out your building areas as you design, so you can check GBA, GFA, and saleable area against zoning limits and your feasibility numbers without leaving the model. Each value below shows how Giraffe calculates it from a geometry’s footprint, levels, and usage settings. Use these values to understand the numbers in Urban and to pick the right property when you build a calculation in Analytics.
To count toward Building Areas, certain properties must be set:
Floor to Floor
Levels
To count toward GFA or NRA, you further need to set the following:
Efficiency
Sell Efficiency
If you set a value to height, the geometry's areas will not be calculated toward building areas.
Gross Building Area (GBA)
Only building sections count toward Gross Building Area (GBA). A building section is a geometry with the usage type Building, Dwelling, or Basement, with Levels and Floor to Floor set. Giraffe calculates GBA on each building section as area * levels. In Analytics, use the grossBuildingArea property for GBA.
Other geometries have no grossBuildingArea. Landscape, paving, roads, land use, and generic or 3D geometries never add to a GBA total. A building section with a Height value, or a basement with a Depth value, has no GBA either.
Gross Building Area (GBA) is the total enclosed floor area of a building, measured from the outside face of its exterior walls, and it includes all levels, even unfinished or unheated ones like basements, garages, and mechanical areas.
Net Area (GFA)
Calculated on each building section as area * levels * efficiency. Only Building, Dwelling, and Basement geometries have a net area.
Gross Floor Area (GFA) is the total floor space within a building, including all levels, typically measured from the inside faces of the exterior walls. The definition may vary by municipality.
Saleable Area (NRA)
Calculated on each building section as area * levels * sellEfficiency. Only Building, Dwelling, and Basement geometries have a saleable area.
Saleable area is the total floor area that can be sold or rented to a buyer, including the usable space inside the unit and sometimes the area of balconies and terraces. Saleable Area directly affects dwelling counts in massing calculations.
Roof Area
Calculated as area - area of geometries with higher stack order in the same building.
The area of the exposed top face of a geometry.
Facade Area
Calculated as perimeter * floorToFloor * levels, minus any wall shared with a touching geometry on the same layer.
Facade area is a measurement of the surface area of a building's exterior front. It is calculated by multiplying the length of the façade by its height, including elements like overhanging soffits, cornices, and protruding columns, as seen in a vertical plane
Facade is quite simple to compute for standalone building sections. However, this becomes more complicated when geometries touch.
Giraffe will attempt to figure out where the sides of geometries should count as interior or exterior walls. The facade settings in analytics and urban control the function.
Parti Wall Area
Calculated as length * floorToFloor * levels where two geometries touch
A party wall is a common dividing structure, such as a wall, located on the boundary line between two adjacent properties, owned by different parties, that serves as support for both structures.