Flat-Vertical
Princeton Envelope Group (PEG): Envelope Categories
The category of the flat-vertical envelope, better known as a slab, (x<y=z) includes those envelopes whose predominant dimensions are parallel to gravity and distributed along a line. Flat-vertical envelopes are generated by the horizontal displacement of a section of space, which, in order to support a specific function, optimizes density, daylight, ventilation, structural constraints, and the building’s relationship with public space and infastructure. Land uses and orientation are crucial drivers for this envelope type. Most mid-rise residential and many office buildings are probably in this category, as they respond to the need to host a large volume of homogenous program. The flat-vertical envelope is primarily determined by the facade-to-facade or facade-to-core depth, hence its laminar organization. Modern urban fabrics are predominantly matrices of flat-vertical envelopes combined in various configurations suited to a particular climate, use, and culture. The flat-vertical envelope usually has a high level of enviornmental performance and a relatively low level of expressive performance.
The building envelope is possibly the oldest and most primitive architectural element. It materializes the separation of the inside and outside, natural and artificial; it demarcates private property, land ownership and social exclusion; when it becomes a façade, the envelope operates also as a representational device, in addition to its crucial environmental and territorial roles. The building envelope forms the border, the frontier, the edge, the enclosure and the joint: it is loaded with political content. At a time when energy and security concerns have replaced an earlier focus on circulation and flow as the contents of architectural expression, the building envelope becomes a key political subject There is no such a thing as a unitary theory of the building envelope in the history of architecture. Previous embodiments of envelope’s theory have addressed either representation or construction technologies. The traditional split between wall and roof construction has prevented the discipline to look at the envelope in a more holistic way, as a single object of analysis. The Princeton Envelope Group aims to develop a general theory of the contemporary building envelope. The research will be tested through symposia and publications, and finally collected in a Manual of the Building Envelope. The Princeton Envelope Group produces concrete architectural proposals with a prototypical format, testing them in concrete scenarios. The research is aimed to produce a series of prototypes to explore the global aspects of the envelope design, and has been structured in 4 different envelope groups, characterized by their aspect ratios: flat-horizontal, spherical, flat-vertical and vertical. The work aims to a prototypical output format. The projects we have identified to be developed in this first edition of the Princeton Envelope Group have been: - Atlas for Sustainable Mixed-Use High-rise Floorplates - Prototype for the American Embassy of the Future. - Manual for the Sustainable Walmart - Catalogue of High-density Residential in Hot-Humid Climates
Vertical footprint
1.0
Taipei 101
Commerzbank
Petronas Towers
Lippo Tower
Chicago Spire
Torre Agbar
Marina City
Aqua Tower
Silver Towers
860 880 Lakeshore Drive
Circle
0.8
Square
Facade RaƟo
Triangle
7m
The vertical envelope has a predominantly vertical dimension and, unlike the flat-vertical (x=y=z) type, a multidimensional orientaiton in plan. The specificity of this envelope category is an intense relationship between physical determination and performances. Because of its scale and technical complexity, functional and enviornmental performances such as daylight penetration and natural ventiliation need to be maximized, while the formal qualities of the envelope play a crucial role in the building’s structural stability. The vertical envelope’s geometric determiniation crucially impacts both the spaces that it encloses and its surroundings. In addition, the visibility of the vertical envelope makes its particularly conducive to iconographic performance. If in the spherical envelope the gap between representative and enviornmental performances reaches a maximum, in the vertical envelope both sets of performances are at their highest level. The collusion between extreme technical performance and high visual impact produces the maximum tension between efficiency and expression, a condition that runs deep in the history of this building type.
1.2
occupiable floorplate
17.6 m
20
m
16 m
12.7 m
16 m
14.6 m
0.6
Cross (1/3, 1/3, 1/3)
Silver Towers
Cross (2/5, 1/5, 2/5)
8m
11.2 m
10.3 m
Rectangle (1:5)
Y Tower
860 880 Lakeshore Drive Torre Agbar 0.4
Star
Petronas Towers
Rectangle (1:10)
Commerzbank
Lippo Tower
džŝƐƟŶŐ dŽǁĞƌƐ
Aqua Tower Marina City
core to perimeter: 20.0 m
core to perimeter: 17.6 m
core to perimeter: 16.0 m
core to perimeter: 14.6 m
core to perimeter: 16.0 m
core to perimeter: 12.7 m
core to perimeter: 10.3 m
core to perimeter: 11.2 m
core to perimeter: 8.0 m
core to perimeter: 7.0 m
Chicago Spire
Taipei 101
0.2
naturally lit floorplate
0.0 0
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
Tower Footprint Area (m2)
floor area : 2160 m² w.o. access to daylight: 787 m²
floor area : 3321 m² w.o. access to daylight: 2683 m²
floor area : 2047 m² w.o. access to daylight: 782 m²
floor area : 1515 m² w.o. access to daylight: 640 m²
floor area : 1120 m² w.o. access to daylight: 482 m²
floor area : 2628 m² w.o. access to daylight: 425 m²
floor area : 1140 m² w.o. access to daylight: 320 m²
floor area : 1762 m² w.o. access to daylight: 480 m²
floor area : 726 m² w.o. access to daylight: 72 m²
The above graph shows the relationship between floorplate area and facade ratio for towers with different footprint shapes. All the curves assume a 3.3 meter floor to floor height typical in residential tower construction. The points represent existing towers showing how real life cases
floor area : 640 m² w.o. access to daylight: 114 m²
correspond to the idealized model. The circle is the tower footprint with the smallest facade area per unit area of interior. As shapes become more elongated or corrugated the facade ratio per unit area of interior increases.
Spherical The spherical envelope’s dimensions are approximately equivalent in all directions; cubic, spheroidal, and polygonal geometries are also (x=y=z) particular cases in this category. In principle, the spherical envelope has the lowest ratio between its surface and volume it contains. The specificity of this type is the relative independence that the skin acquires in relation to its programmatic determinations, as functions are not strongly determined by adjancency to the outside and, therefore, by the form of the envelope. This often implies a wider variety of programs inside and a hetrogeneous enviornmental content. Sperhical envelopes generally enclose a wide range of spatial types with specific functions, rather than a single spatial condition. Unlike other envelope types in which the border between public and private occurs on the surface of the container, the spherical type often contains gradients of publicness. Spherical envelopes often correspond to public buildings that gather a multiplicity of spaces, such as city halls, courthouses, libraries, museums, and arenas. In the spherical envelope the gap between expressive and enviornmental performances is at a maximum, with low enviornmental and high expressive performances.
Aldo van Eyck Orphanage Double House
Farnsworth
SA / V (m2/m3)
Toledo Glass Museum Taipei 101 MASP
Westin Peachtree
Free University Mpreis McCormick Campus Center
Nexus Housing
Aplix
Torre Agbar Centraal Beheer Office Building
Casa da Musica Villa VPRO
Laban
London City Hall shows the three different types of spherical buildings as The above diagram Aqua Tower Gifu Housing Unite determined by the previous graph. Examples of each type are shown below. Silodam
Stansted Airport Jeddah Golden Resources
Baker House
Pentagon
Tokyo Opera House
Mall of America
Water Cube Mies Convention
The graph above establishes the definition of the spherical building type. The red line shows the surface area to volume ratio of a perfect geometric sphere. The black line shows the surface area to volume ratio of a perfect cube. The dotted black line shows the empirically determined variability in the type while still being close enough to the ideals to be considered spherical.
The gray shaded region is the area of the graph that is considered spherical. No geometric shape can have a smaller surface area to volume ratio than a perfect sphere so the gray region never goes above the red line. Deviations from the ideals beyond a certain threshold cannot still be considered spherical and therefore the dotted line bounds the bottom of the gray region.
Buildings are plotted as points indicating their surface area to volume ratio. Buildings that fall within the gray region are considered spherical and shown as black dots. Buildings of the tower type are shown as red dots, flat horizontal buildings are shown in green, and flat vertical buildings are shown in blue.
The zoomed out graph on the left shows that spherical buildings don't get as large as flat horizontal or flat vertical buildings. Also the largest buildings on the graph, the Mall of America and Mies' Chicago Convention center have relatively large surface areas for their enclosed volumes.
This graph defines the three different scales for spherical buildings. The ideal cube and sphere are plotted as in the previous definition graphs but here the surface area to volume ratio is plotted relative to the rough diameter of the building. When the diameter of a building is small the surface area to volume ratio increases and when the diameter is large the surface area to volume ratio
Wal - Mart #1800
Glass Box
Flat-Horizontal
decreases. This can be understood by inspecting the equations for the volume and surface area of a sphere. Because of this change in surface area to volume ratio based on building scale a program to scale correspondence exists. The two scale thresholds are indicated by vertical dotted lines.
Residential Sphere
Big Box
Corrugated Box
Mat Building
Mothership
0.6
Mat Building (proliferation of courtyards, general edge irregularity; i.e. Van Eyck’s orphanage) Mother Ship (monolithic figures; i.e. Mies’ Convention Center, Water Cube, Jin Yuan Mall) Donut (single, large, central courtyard; i.e. Pentagon, Jeddah)
Jin Yuan Mall
Mall of America
The Pentagon
Early figures produced by examing SA/V ratios in relation to P/(2X+2Y), our method for calculating invagination, seem to bear out this thesis. It is, however, not the identification of evolutionary stages that interests us but rather in that of its gaps and overlaps and the limits of the FH type, for identifying these areas will provide opportunities for more focused inquiry as to their origins, be they programmatic, economic, social, etc.
Mothership
Mat Building
Donut
Aldo van Eyck Orphanage Aldo van Eyck Orphanage
0.5
Double House
Broken Box (small courtyards begin to appear, corrugation of edges occurs; i.e. Aplix Factory)
FBU
Tokyo Opera House, Jean Nouvel
0.6
0.5
Big Box (featurless facade, some skylighting, i.e. Wal-Mart) Aplix
Program Detached from Envelope
Casa Da Musica, OMA
Donut
Flat Horizontal building types from small to large: Glass Box (prismatic form, large expanses of facade glass, impermeable roof; i.e. Farnsworth House)
Civic Sphere
Double House, MVRDV
Corrugated Box Big Box Glass Box
Wal - Mart #1620
Laban Centre
MAAB
The category of flat-horizontal envelopes includes those in which the horizontal dimensions are considerably larger than the (x=y>z) vertical. Buildings like airports, train stations, factories, trade fairs, convention centers, markets, and retail and leisure complexes generally belong to this category. The political performance of flat-horizontal envelopes lies in the delimitation of edges, frontiers, and boundries, and in the sheltering of large-scale atmospheres operating primarily through the articulation between natural and artificial. Since a comprehensive perception can only be obtained from an aerial perspective, flat-horizontal envelopes are experienced in a fragmented manner are, therefore, less concerened with representation and figural performance than with the organization of material flows: traffic, ventilation, daylight, security, etc. The flat-horizontal envelope usually presents relatively low affective and environmental performances.
21st Century Museum
Double House
0.4
0.4 Farnsworth
Farnsworth
SA / V (m2/m3)
21st Century Museum
21st Century Museum
SA / V (m2/m3)
0.3
0.3
Toledo Glass Museum
Toledo Glass Museum
Taipei 101
Baker House
MASP
Westin Peachtree
MASP Gifu Housing
Free University
0.2
McCormick Campus Center
London City Hall Silodam
Villa VPRO
Aplix
Centraal Beheer Office Building Casa da Musica
Centraal Beheer Office Building
Casa da Musica
Gifu Housing
Mpreis Nexus Housing Silodam McCormick Campus Center
Aplix
Torre Agbar
0.1
Free University
0.2
Mpreis Nexus Housing
London City Hall Villa VPRO Laban
Laban
Aqua Tower Unite
Stansted Airport Jeddah
0.1
Westin Peachtree Torre Agbar Aqua Tower Unite
Golden Resources
Baker House
Pentagon
Taipei 101
Pentagon
Tokyo Opera House
Tokyo Opera House
Golden Resources Mall of America
Water Cube Mies Convention
Mall of America
Water Cube
Stansted Airport
Mies Convention
0
0 139
1555
1800
2603
3180
3650
4235
4290
7549
9278
9308
30000
32045
35000
35344
48400
56000
176000
197449
1102500
0
50000
100000
Footprint (m2)
Flat Horizontal
Flat Vertical
Vertical
150000
200000
Footprint (m2)
Sphere
Flat Horizontal
Flat Vertical
Vertical
Sphere
250000