Parametric Design as a tool for Mass Housing Development in
Ethiopia
Rajendra Kopil Kunwar1, Dr. Sheeba Chander2, Yonas Assefa3
1
Assistant Professor, Faculty of Architecture & Planning, Arba Minch University, Arba Minch, 21, Ethiopia,
email: architectkunwar@gmail.com
2
Professor, HOD, Department of Architecture, Hindustan University, Chennai, 600001, India,
email: sheebac@hindustanuniv.ac.in
3
Lecturer, Faculty of Architecture & Planning, Arba Minch University, Arba Minch, 21, Ethiopia,
email: yonas.assefa3@gmail.com
Abstract — this exploratory paper takes prefabrication as a design solution to mass scale housing production.
This paper tries to review the physical hindrances surfaced in the mass housing strategy for social housing
adopted by the Government of Ethiopia. Condominium housing which has become the face of the housing
fulfillment initiations for the masses has been evaluated for the physical failures. Condominium projects
have received mixed reactions from both public as well as professionals in the country. The major questions
have been raised on the cost and the intended target user group.
Parametric design has been a major force worldwide to push architectural design and construction industry to
new horizon. This paper tries to evaluate the aspects of parametric design which can help on the cost
reduction process of construction mainly through prefabrication techniques. This paper evaluates the
computational techniques that will be most relevant in the process of cost reduction in mass housing like the
condominium.
The paper comes up with a concept model under which the digitalization process will be done through use of
computer software’s such as Rhino and Grasshopper with various plugins. The outcome is a prototype which
will establish the feasibility as well as workability of the model. Finally the paper concludes how this
digitalization process under parametric tools will enhance the prefabrication strategy for mass housing.
(Keywords: Parametricism, Condominium, Social housing, Pre-fabrication)
1.
INTRODUCTION
Housing forms an indispensable part of ensuring human dignity since it is essential for health, privacy and personal
space, security and protection from inclement weather, and social space. In every country children, men and women
sleep on sidewalks, under bridges, in cars, subway stations, and public parks, live in ghettos and slums, or "squat" in
buildings other people have abandoned. The United Nations estimates that there are over 100 million homeless people
and over 1 billion people worldwide inadequately housed [1].
In Ethiopia, these problems are felt broadly and in depth throughout urban centers across the country due to various
reasons. One major cause is the irregular pattern of urban growth leading to the emergence of slums’ and homelessness.
This is especially true for the situation in Addis Ababa where housing is a serious problem in terms of availability and
quality. The accumulated housing backlog is estimated to be 300,000 units. Moreover, 60,000 units are needed to
accommodate the population increase of 7-8% p.a. mainly as a result of migration from rural areas. [1] Many other urban
areas such as Gondor; Dire Dawa and Harar; Mekelle, Adigrat, Shire Endasillasie, Maichew and Humera; and Ambo
also have similar housing problems [1].
The government of Ethiopia is implementing Integrated Housing Development Program (IHDP) since 2005 (World
Bank, 2015:34). But it has been criticized regarding its effectiveness in terms of affordability and others aspects. The
UN-Habitat publication on 2011 about “Affordable Land and Housing in Africa” put Ethiopia as a prominent example
for the challenge of insufficient affordable urban land and housing provision to accommodate thousands of new urban
dwellers who move to cities in search of the greater opportunities cities can provide. It states that: ‘Ethiopia currently
has a relatively small urban population (16.6 percent in 2010), yet its expected urbanization growth rates are above 3.76
percent for the coming 15 years (2010-2025). Such growth will place additional housing pressure on Ethiopian cities,
such as Addis Ababa; that already have serious housing problems, evidenced by the current high proportion of urban
slum dwellers, 79.1 per cent.’ (UN Habitat, 2011:4). One statement also adds that “It needs a system that deals with the
case that, “affordable housing is inadequate and adequate housing is unaffordable” (UN Habitat, 2015).
Ethiopia also looked towards condominium housing as one of the major factor under the IHDP to achieve its ambition.
But various studies have shown that even if addressing the needs of low and middle income inhabitants are the main
objectives of the program. That’s why the government took a lot of action to minimize the price of condominium house
in favor of the target class. The support delivered by the government by two means firstly by making free payment like
provide land with free of lease payment, duty free for imported construction material, free from value added tax and
secondly by means of full coverage of certain cots like cost of main road building, cost of infrastructure building, cost
of main road water installations, cost of sanitary line installations, salaries and regular expenditure. Even though all the
above supports expected to reduce the cost of the condominium houses significantly, but still people are complaining
the price is unreachable to target groups. In the current status of the project there is affordability problem in terms of
cost, convenience and quality of the houses.
1.1
AFFORDABILITY OF CONDOMINIUM HOUSES:
When the 40/60 condo housing schemes began in 2013, AASHDE set the price at 2289, 3300 and 3860 birr per square
meter for one, two and three bedrooms respectively. But in the first and the last 40/60 condo lottery the agency
transferred the price increase of two bedroom apartments by 91,470 Birr while 3 and 4 bedroom apartments faced a
110,650 Birr and 124,000 Birr price hike respectively. While in the recent 20/80 condo draw, Studio houses were sold
at 2,483 birr per square meter while one, two and three bedrooms sold at 3,438 birr, 4,394 birr and 4,776 birr
respectively [2].
Tigist Ayele Gebrewold in her thesis titled “Condominium dwellers housing quality perception and satisfaction in
Addis Ababa” studies the cost and affordability factors in major condominium project sites in Addis Ababa ( Jemo II,
Bole Ayati I, Gotera, Lideta ). The findings reveal a clear scenario of cost of the condominium with its relation to
affordability. The findings are as below [3-4]:
a. The result reveals that majority (60%) of tenants and homeowners spend more than 30% of their income for housing
rent and mortgage. In the extreme 12.6% of homeowners were unable to repay their mortgage and it paid by their
children. According to Cook and Bruin (1994) if the housing cost exceed 30% of income it is considered as burden for
residents. Another study by Elsinga and Hoekstra (2005) show that housing cost has significant influence on lowering
housing satisfaction. UN Habitat (2009) define affordable house, as housing cost do not take up a high portion in their
income. The finding implies that condominium was expensive house for majority of dwellers. It also indicated that high
housing cost was main contributing factor for low affordability index and dissatisfaction.
b. An examination of survey result reveals that most of the respondents were dissatisfied with affordability domain.
This claim is affirmed by the result that shows that 32.7%, of the respondents were satisfied, 52% were dissatisfied and
15.3% were neither satisfied nor dissatisfied. This shows condominium was unaffordable for the majority of
respondents.
1.2
FAILURES FOR COST REDUCTION OF CONDOMINIUM PROJECTS:
The major reasons that are associative to the cause can be elaborated as follows [3-4]:
1. Professional incompetency of the contractor: the contractors lack enough skills for construction to finish the given
project on due date. This creates a delay in the schedule thereby resulting in huge differences in the change of the cost
of materials. Therefore professional incompetency is one of the problems that lags condominium construction harshly
and made the project ineffective in terms of cost, quality and time.
2. The Procurement process: Creating efficient and effective procurement system is very crucial activity for such type
of time bounded and scheduled activity. In condominium construction process there is huge mobilization of material
resources but still expeditious procurement processes does not exists yet as required. The procurement process is greatly
extended and the necessarily input material is not delivered timely.
3. Lack of Micro and Small Enterprises: Micro and small enterprises are participate in the condominium construction
program as a sub-contractor ,as a supplier that provide basic input of the building like ditch , precast, terrazzo etc. In
each condominium blocks (40 %) of the construction portion is covered by them. So there efficiency is very vital in
speed and quality of the construction. However studies shows that the MSE also have their own contribution on delay of
the cost of construction process and the poor performance project office.
1.3
PREFABRICATION AS A TOOL TO COST REDUCTION:
In the present condominium designs in Ethiopia the government has adopted prefabrication to a small extent. Still the
potential of prefabrication is not exploited fully. Only few elements in the construction such as staircase, common
corridors, doors and windows and roofing have been applicable to prefabrication techniques. But when we try to
invested similar projects we see a huge gap which could well provide a key to the cost reduction of condominium
projects in Ethiopia drastically.
Goodier and Gibb [5] stated that prefabricated building can be generally classified into five levels according to the
prefabrication degree applied on the product. However, to clarify classification, the original term “pre work method,”
which consists of “prefabrication,” “preassembly,” and “modularization,” should be initially defined. Modularization
generally refers to pre constructing a complete system in a location away from that on the job site, and then transporting
the completed system to the site [6]. It is categorized as a Fourth-level “Modular System” [5]. According to Lu [7],
modular systems are generally similar to hybrid systems; however, they typically consist of multiple rooms with 3D
units. Modular systems can be complete factory-built houses or apartment blocks, which are constructed and
preassembled.
Industrialization describes all pre work forms (prefabrication, preassembly and modularization), which relatively
implies the use of fully integrated and automated project processes [6]. Uttam et al. [8] stated that industrialized
building systems refer to the complete integration of all subsystems and components into a general process that fully
applies industrialized production, transportation, and assembly techniques. Cost, schedule, quality, and safety issues are
the primary motivations in employing prefabrication and preassembly.
Prefabricated building has a relatively low uptake in construction industries worldwide despite its inherent economic,
environmental, and social benefits. Although motivations in using prefabricated building help determine its use as an
option, the decision to implement such technology is influenced by the balance between potential benefits and
impediments. The possible barriers to prefabricated building adoption are industry practices and techniques, supply
chain management and logistics, professionalism of the industry, and construction market risks. Meanwhile, many other
aspects involved in adopting this technology require attention. Transforming the use of prefabricated building into
economic rewards requires training, organizational changes, and procurement arrangements in the construction
industry. Thus, implementing prefabricated building technology requires a complete restructuring of the construction
industry. The government should encourage and motivate the private sector to participate in developing such structures.
PARAMETRIC DESIGN:
1.4
Parametric design is a process based on algorithmic thinking that enables the expression of parameters and rules that,
together, define, encode and clarify the relationship between design intent and design response. [2]Parametric design is a
paradigm in design where the relationship between elements is used to manipulate and inform the design of complex
geometries and structures. The term parametric originates from mathematics (parametric equation) and refers to the use
of certain parameters or variables that can be edited to manipulate or alter the end result of an equation or system. While
today the term is used in reference to computational design systems, there are precedents for these modern systems in
the works of architects such as Antoni Gaudí, who used analog models to explore design space [9].
Parametric modeling systems can be divided into two main types:
•
Propagation-based systems where one computes from known to unknowns with a dataflow model.
•
Constraint systems which solve sets of continuous and discrete constraints [10].
Form-finding is one of the strategies implemented through propagation-based systems. The idea behind form-finding is
to optimize certain design goals against a set of design constraints [10].
Generative design is an iterative design process that involves a program that will generate a certain number of outputs
that meet certain constraints, and a designer that will fine tune the feasible region by changing minimal and maximal
values of an interval in which a variable of the program meets the set of constraints, in order to reduce or augment the
number of outputs to choose from [11]. The process combined with the power of digital computers that can explore a
very large number of possible permutations of a solution enables designers to generate and test brand new options,
beyond what a human alone could accomplish, to arrive at a most effective and optimized design. It mimics nature’s
evolutionary approach to design through genetic variation and selection. Parametric modeling is a modeling process
with the ability to change the shape of model geometry as soon as the dimension value is modified. Parametric
modeling is implemented through the design computer programming code such as a script to define the dimension and
the shape of the model. The model can be visualized in 3D drafting programs to resemble the attributes of the real
behavior of the original project. It is quite common that a parametric model uses feature-based, modeling tools to
manipulate the attributes of the model.
2.
THEORETICAL FRAMEWORK
It is evident that Ethiopia is facing a grave problem of housing sufficiency. The backlog in housing supply is too huge
to be met with the current policies and construction processes. Also researches clearly show the hindrances in cost
factor optimization which directly influences the affordability factor of housing supply. Combined issues of various
degrees in construction industry as well as policies framed around the construction of condominiums clearly shows the
unreliability aspect of the present construction practices right from procurement, skilled labor availability, project
management and implementation as well as timely execution of the task. All these have been a major contributor to the
cost addition aspect in the condominium projects.
Hence the need of an alternative approach of construction is evident. The expectations from this alternative will be cost,
schedule, quality, and safety. Pre fabrication approaches completely succeeds on all grounds and proves to be the best
possible solution to trim down the housing deficiency as well increase the supply rate at phenomenal pace so that the
housing sufficiency can be achieved at the earliest. But prefabrication cannot be only applied solely as the alternative as
pre fabrication can be associated with major design challenge of modularization of the requirements and demands.
Parametric approach is the latest trend which comes in support of the prefabrication ideology so that it can be quantified
and measured to the needs and demands that should be met to the end users. As the goal of parametric design is to add
the dimensions and any other specific information needed for functionality and manufacturability it will be the best
associative tool for the design for prefabrication. The specific material is also selected if it has not previously been
designated. In other words, parametric design supplies all the dimensions, tolerances, and detailed materials information
critical to the design consistent with Engineering Design Specification.
3.
PROPOSED ACTION PLAN
The procedure of parametric-generative design constitutes the four major elements as presented below [12].
a. Start conditions and parameters (input)
b. A generative mechanism (rules, algorithms, etc.)
c. The act of generation of the variants (output)
d. The selection of the best variant
The paper targets to establish the fact that parametricism can be applied as the most efficient tool through developing
design inclusive of variants which helps parameterizing the dimensional modular co-ordination principles which in turn
will facilitate and enhance the implementation of prefabrication construction methodology in Ethiopia. For the purpose
of achieving a fully automated parametric outcome Rhino and Grasshopper software packages were used in integration
as a computer tool to test the working of the proposed model. Rhino is a 3D modeling software that authorizes the
designer to link the layout to its underlying parameters by a plugin called Grasshopper. Grasshopper is regarded as the
most suitable parametric modeling platform embedded in Rhino for developing the design variant algorithms due to its
powerful parametric programming capabilities [13]. This is a graphical algorithm editor tightly integrated into Rhino 3D
modeling tools and features an advanced user interface. The main window consists basically of the component
‘palettes’ and the ‘canvas’ or the user interface. The major interface of the algorithm development in Grasshopper
deploys a node-based editor in which data is processed from a component by connecting wires which always connect an
output grip to an input grip where data can either be defined locally as a constant or imported as a variant parameter.
This paper aims to create a model for mass housing development across the nation irrespective of regions. The model
accomplishes its objectives through three progressive development stages namely:
1. Basic unit developments (studio types, 1BHK, 2BHK & 3BHK)
2. Block developments
3. Site development
The model’s ideology will be tested through the proposed fully digitalized parametric model output which can also be
described as a working prototype that can establish the success expectations from the parametric approach for mass
housing.
Fig. 1 Stage 1 development model
Fig. 2 Stage II development model
Fig. 3 Stage III development model
Fig. 4 Flow chart diagram for work process
1.
BASIC UNIT DEVELOPMENT:
The fundamental ground on which the model stands is the dimensional co-ordination to be achieved that can facilitate
prefabrication strategy as a whole. Hence it is extremely important to create a modular co-ordination within different
units within the condominium. The primary unit building block will be established and further then these units will
come together to create the best effective basic unit whichever needed studio type, 1BHK, 2BHK or 3BHK.
2.
BLOCK DEVELOPMENT:
The basic units which will be defined with various modularization concepts will be interweaved according to new set of
modular data such as corridor width, staircase, building footprint and so on. Also space associative aspects such as
orientation, lighting, ventilation etc. will be merged into the grids so as to achieved better realistic and workable
outcome.
3.
BLOCK DEVELOPMENT:
The blocks which were developed in stage II of the process will be again taken as a input and remodeled for
multiplication according to set requirements under various variables as built space, un built space, access, block
spacing, infrastructure etc. Finally this stage will give us a complete outcome of site, building blocks and block details
which can be used to generate prefabrication inputs for the industry.
4.
PROTOTYPE DEVELOPMENT & STIMULATIONS
Although parametric design isn’t a new phenomenon, it emerged 50 years ago when Sketchpad was created by
Sutherland, it has become an area of considerable interest over recent decades. As Sutherland observes: “It is this ability
to store information relating the parts of a drawing to each other that makes Sketchpad most useful” [14]. We have a
hunger for far greater computer power to allow the multi-parameter decision-making to take place in real-time [15].
This algorithmic model is developed with a simple linear rectangle with fixed range of area parameters in order to be
occupied.
Units
Studio type
Area Requirements
30-35m2
One Bed Room
(1BHK)
45-50m2
Two Bed Room
(2BHK)
60-65m2
Three Bed Room
(3BHK)
90-95m2
Fig. 5 Number sliders
The above figure shows number sliders in order to decide the triggers to change the center of movement and rotation.
Through fixed decide the triggers to change the center of movement and rotation through fixed range of algorithmic
number.
Fig. 6 Defining specific housing per unit area in the block
Inputs for the linear rectangle are defined and after that it is associated to the specific housing per unit area in the block.
The next stage is to get the geometry from the area parameters which are fed as fixed range of parameter in order to get
the shuffling probabilities of a length and width of the Rectangular area. The data for the area requirement is to be filled
manually with its fixed range of parametric statistic data.
Different arrangement layout for a single unit (generation of a variant output):
A possible flow and circulation are fed as a parameter of room instances with the area requirements as a bubble. The
following process was adopted further for generative design:
-
A range input of maximum and minimum number of areas needed via a Magnetized FPG where the user is
able to organize the area requirements of the floors (room instances) dimensions and their order
-
Assembling Bubbles side by side with their flow chart and circulations
-
Evaluating the possible outputs of arrangement parameterized through movement rotation and possible
pixilation through flexible Range and Domain
-
Extracting the module dimensions of each surface
Fig. 7 Studio type unit
Fig. 8 1BHK type unit
In the fourth step, an algorithm was established in order to apply module dimensions generated floor plans and connect
them through cross-lines on Block development. This was through using algorithm in both horizontal and vertical
components in which the procedural instruction of horizontal components was described representatively by parameters
to define the computation with minimum circulation and best possible solution.
Implementing Studio and 1BHK reference preferences in vertical modularization through number sliders to extract
variety of module coefficients
As a result of developing the algorithms to parameterize the arrangement and adjacency and compute the suitable
circulation analysis of a space in a least possible set of arrangements, this three significant issues raised as a standard
for preference frequencies along with three datasets of Area requirement alongside total number of spaces to be
stretched along horizontal and vertical frequencies were obtained.
Fig. 9 Optimization solver
Galapagos was launched and the data logger was set to record the results within the range of the Domain. Within this
range, the minimum and maximum of required area recorded at different values of variables to optimize the total need
of space for all the blocks to be generated. The data was then further associated with other variants to generate a block
layout.
Fig. 10 Block development
5.
SUMMARY & CONCLUSIONS
This paper has described computational design methods to achieve parametric solutions which can improve the
solutions for modular mass housing projects. The parametric approach is controlled under the aim of achieving
dimensional co-ordination so as to very well facilitate the prefabrication strategy which in turn will help to achieve
faster and cost efficient means of delivery system. Software aid has been used to depict the efficiency of the model as
well as giving a prototype outcome that can verify the reach of the prescribed model.
The output prototype concludes that parametric modeling facilitates the logical process of across field communication
and therefore assists with interrelation of multiple variables which can inter loop under guidelines to give an outcome. It
also establishes that being able to evaluate design problems in an integrated way using multiple variations would only
further improve the process in addition to enhancement in performance of design solutions.
The research establishes that such parametric approach will help in ensuring an integrated system of design that will
ensure a smooth transition from design to execution to construction. It also enables a complete control over the modular
aspects so that it will facilitate an organized and cost efficient outcome for prefabrication. It can be also argue
theoretically that parametric approach has benefits related not only to prefab construction but also towards space quality
enhancement and organization.
Furthermore this research creates multiple windows for further researchers from the field of construction management,
urban planning, urban design etc. Also designers are left with lot of space where research can be carried out in
individual stages of the entire model. Having defined and testifying the application potential it is not wrong to state that
we are looking into the new future of our urban cites where we can acclaim to be motivated by sustainable achieved
goals.
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