Generative Microhousing
type | ARCHITECTURE // BIOPHILIC DESIGN status | COMPLETED year | 2019
in partnership with | SAYALEE GOLATKAR / NISHANT PAI
Fractal Concept
Using mathematical concepts to create an "ideal" built form (both in the aesthetic sense and structurally) is not a novel notion. For centuries, Western Architecture has inculcated the Golden Ratio (phi, the ratio of 1:1.618) into spatial organisation, or the proportions found in fenestrations. Fractal architecture has arguably been around for far longer than that. Fractal laws such as self-similarity, repetition and scale are found in a myriad of Hindu temples and Buddhist monasteries, along with various tribal settlement typologies.
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In the structure of a Ba-ila settlement (Ba-ila is an indigenous tribe in Zambia), as seen in the image below, the spaces are organised in a fractal manner, each space creating a series of ellipsoids. In level 1 of the fractal, the largest ellipsoid forms the outer boundary of the settlement. In level 2 of the fractal, the mid-sized ellipsoids form the main living spaces, arranged around the periphery of the largest ellipsoid. Around each living space, a series of smaller ellipsoids form level 3 of the fractal, small spaces that are used to store personal possessions and food.
Fractal organisation of the Ba-ila settlement, via Eglash, Ron. (2005). Fractals, Complexity, and Connectivity in Africa.
Using a similar concept, Generative Microhousing is a development of form by repeating and rotating individual modules to create local clusters, which are repeated and rotated to form communal clusters. The communal clusters undergo the same operations to form a supercluster. The open areas formed in the negative spaces of the generated building increase by degrees from the local cluster to the supercluster - where the smallest public space will serve a cluster of three housing units, the mid-sized public space serves nine housing units, and the largest public space serves all twenty-seven housing units. This organisation is seen in the diagram below.
Spatial organisation built up with fractal growth form, mimicking the build up of a leaf through organelles, cells, tissue and leaf form
Housing Units
Three kinds of housing units, from left to right: the worker's unit; the single family unit; and the double family unit (4 individuals)
The proposed housing is designed to accommodate one hundred and eight individuals in twenty-seven units. Our target demographic was the migrant worker population in Mumbai. Several kinds of migrant workers flock to the city from rural areas in search of economic security. Of these, we narrowed our demographic to three principal kinds of migrant workers: the individual workers, the family, and the nuclear family.
The individual worker's unit can house men or women who have travelled to the city, leaving their family in the rural areas. The family unit is designed for those workers who migrate to urban areas with their families, or start a family while they have jobs in the city. This unit accommodates one family of four individuals. Finally, the double-family unit houses two families of two individuals each.
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Each unit is designed with a kitchen and living area and two toilets on the ground floor - and depending on the type of unit, the bedrooms are organised in lofts or as part of the living area. The kitchen and living areas open partially into the community space shared by three units, enlarging the area used for family or neighbour functions. While the external form and layout of each unit is largely the same, amounting to about 350 sq. ft., the internal spaces are modulated to provide relevant spaces for each kind of worker, as per their requirements. Lofts in the family unit, for example, are designed as a study area for children. In the double-family home, both the lofts are bedrooms and the area beneath becomes a semi-private living area for each of the families. By modulating the spaces within the units, we're able to create a repeating framework with several functions - which means all units are largely similar, and can be used as individual elements to build the larger fractal geometry.
Supercluster Layout
A rendering of all 27 units arranged as a supercluster, showing all the public spaces arranged by increasing scale of the fractal.
The units seen in the previous section are arranged to form a congruent cluster using two commands: replicate and rotate by (+-) 90 degrees. These two operations, performed twice, generate level 1 of our fractal organisation - three units strong.
Further, we use a third command that is applied to the cluster and it's commands: repeat. By repeating the same commands with the whole cluster, we can do not need to create a new set of rules governing the cluster - the same two commands, performed twice, will generate a mid-sized cluster nine units strong - level 2 of the fractal.
And when the same rules are applied once more, to the mid-sized cluster, that gives us a total of twenty-seven units, the supercluster - level 3 of the fractal - housing one hundred and eight people in total.
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One of the main issues with mass housing in the city is the fact that once you scale up or attempt to replicate the same form over and over, you create buildings with very little open space, light and ventilation. However, no matter how many times this concept is scaled up or repeated, assuming the same three commands are followed, the generated building form ensures that all units have more than two open facades. The reason for this, theoretically, is that as we add more iterations (level 4, eighty-one units, level 5, two hundred and forty three units, and so on), the associated open space increases exponentially, and what seems like a volume at a lower level takes on the appearance of a "skin" at higher levels. And mathematically, because of the fractal nature of the form that we are generating, the proportion of surface area to bound volume (i.e., open spaces) keeps getting larger. In a sense, this is a Koch snowflake generated in reverse. In a Koch snowflake, the area (a 2-dimensional entity) encompassed by the curve increases by an infinitesimal amount, while the length of the line (a 1-dimensional entity, the "skin") increases by an infinite amount. Theoretically. As an exercise in architectural realism, this concept would probably fall through or have to be re-modelled for larger scales - however, it does give us a straightforward solution to the issue of lighting, ventilation and open spaces for a large volume of people.
Delineating Services
As established, fractally generated designs are helpful because they eliminate the need to design complex master-plans whose design changes at each iteration or scale, and they can also be taught easily to be assembled by any labour force, whether it is skilled or unskilled. Generative design also ensures that individual units get the same amount of public space, area, ventilation and light as all others.
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The advantages of a generated design means that all kinds of services can also be organised using the three commands, i.e., replication, rotation and repetition. Below are a set of four diagrams showing how water services, stormwater drains, greywater discharge systems, and public spaces or areas for capital generation are organised around the fractal housing form.
Water supply pipes, following a fractal branching pattern
Greywater discharging into reed beds for each unit
Public spaces and areas for generating income organised accommodating the scale of each cluster
Rainwater collection of the entire site including a small tank for three units, a mid-size tank for nine units and a cluster tank for the whole area
A site plan showing all the housing units clustered around the various scales of public spaces generated by the fractal form.
Material Tectonics and Structure
Considering the fact that the influx of migrant workers into the city is only increasing, and the building is designed to replicate, or "generate" itself fairly easily, we considered a very low-tech material palette that can be sourced and worked on by both skilled and unskilled labour with ease. In addition, using primarily natural materials, with very little concrete and steel, and upcycling parts from decommissioned shipping containers, we are able to reduce the carbon footprint of construction of each unit to nearly zero.
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The main structural framework is made using built-up bamboo sections and box girders from the frame of a shipping container, organised as five bamboos (in the case of columns) and the box girder as the beam.
The slabs are roller-deck slabs, reducing the amount of material and reinforcement necessary to construct them. The deck of the slab is made from pre-cut portions of shipping containers that are reinforced with built-up beams made of recycled steel. On the deck, there is a layer of insulation that levels the surface and creates a plane for a bamboo structural lattice to be placed, onto which a level layer of composite adobe and lime flooring is applied. This is an entirely zero-concrete slab.
The infill walls and external walls are respectively single- and double-layer prefabricated wattle-and-daub clay sandwich panels, constructed by fixing a wicker weave onto a bamboo framework, and applying a layer of mud plaster to each side. This panel is then allowed to dry in the sun and treated with waterproofing layers and fitted into the bamboo and steel framework.
The roof, like the slab, is constructed using bamboo purlins and a pre-cut decking sheet from shipping containers. However, because of the high volume of rainfall in Mumbai, the roof above the decking is a mix of concrete and mud, "mudcrete", topped off by a layer of clay shingles.
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All the panels, slabs, structural elements, and roofing systems are designed as modular elements that make up the entire unit. This ensures that all units are entirely self-similar in construction and there are no minor discrepancies that could throw off the alignment of two units. Manufacturing the panels and slabs in higher numbers is more cost effective, and even if there is an excess of these modules, they can be used in further expansion of the building, or maintenance.
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Moreover, among the primary functions in the public spaces are those that are dedicated to manufacturing or building these panels using raw materials from the bamboo groves and the clay beds that are on site, making this an extremely sustainable building in terms of resource usage and waste generation. A detail of how all the parts fit together is shown below.
A typical wall section through the external walls of one of the units, showing each element used and its composition and structure
A section of the whole cluster, showing material tectonics and the articulation of single and double-height spaces