Building Investment (Jan - Feb 2017)

Special Feature
Plug and Play Precast: Design for flexible
prefabricated housing in tropical country
Contributed by Dr Foo Chee Hung, Construction Research Institute of Malaysia (CREAM).
REDUCING construction costs while meeting consumers’ various
needs for housing quality are the foremost challenges faced by today’s
house builders. This is well demonstrated in the affordable housing
development as this type of housing is solely designed and built based
on the economic concepts of housing. These houses might meet
the minimal shelter requirements but they possess a limitation of
sustainable architectural design theory. Most of them are criticised for
their lack of storage area, small size and deep location of the kitchen,
complicated partitions, less cross ventilation, inhabitable and small
bedroom etc. To ensure that both the affordability and sustainability
are embedded in the affordable housing development, a design
system that incorporates open plan, standardisation of construction
elements, as well as responding to the social requirement and local
climate condition, is necessary. In this sense, the Divergent Dwelling
Design (D3), which is a combined housing design and construction
system that makes use of the prefabrication construction to
produce a variety of housing design options that meet possible user
requirements not yet identified at the design stage, while retaining
principal uniformity to facilitate the execution of simple but accurate
construction with a minimal initial cost, is introduced.
D3 adopts the open plan concept and utilises the Industrialised
Building System (IBS) construction method. Its basic architectural
plan is a square shaped plot, having a plurality of “dynamic” space lots
(where the bathroom, kitchen, and other dwelling services are located)
arranged peripheral of the plot so as to be in contact with the outdoor
environment; and a plurality of structures such as the dining room,
bedroom, or any other spaces located in the “core” space lot which is
capable of being arranged, modified, and customised in plurality of
designs according to the user’s needs (Figure 1). Every D3 building is
designed and built in such a way that both the structure and infill of
the building are treated as separate entities in order to optimise the
efficiency of building assembly and modification. The basic layout
can be configured into various plans, simply by partitioning the core
space lot or rearranging the location of bathroom and kitchen within
the dynamic space lot (Figure 2). This is similar to the automotive
industry, where each individual functional unit is freely bonded with
the core structure to serve different occupants’ requirement. In terms
of sustainability, D3 fully incorporates the passive design strategies
that respond to the tropical climate. In D3 housing, cross ventilation
is optimised by having an elongated dwelling shape together with
minimal partitions or interior walls. This is not only allowing for
easy passage of air and cross-ventilation, but also encouraging a good
lighting of the interiors, as well as the flexible use of space. Besides,
the parallel arrangement of windows and the placement of high
louvres on the internal walls of each bedroom also ensure adequate
wind flows through the house. By setting back the exterior walls 2.1m
from the peripheral of the dwelling, no walls are exposed directly
to the outdoor environment. Solar radiation is, thus, effectively
controlled with the large thatched upper floor ceiling that acts as
the overhang. Together with the installation of adjustable louvres or
grilles as building façade, a barrier is created which not only provides
good shading and protection against driving rain, but also to some
extent maintain the quality of openness for ventilation and outdoor
views. The setback also creates an open porch that makes it possible
for occupants to enjoy the open-air landscape. With careful planting
or selection of vertical green, the open porch can function as a buffer
corridor that aids in air circulation. The presence of air movement
will then enhance the evaporative and convective cooling from the
Figure 1: Various shapes of D3 basic dwelling unit.
Figure 2: Different variations in the arrangement and partitioning of D3
basic dwelling unit.
16 Building & Investment | www.b-i.biz