How does bamboo perform
thermally and aesthetically as screen walls in various climatic locations?
Introduction
There are several famous architects who explored the
potential of bamboo and get inspired in their designs to apply the inherent
properties of this plant in their work. We can see how bamboo structure can produce
various forms and aesthetics. Moreover, bamboo has a greater tensile strength
than steel. Therefore it can be easily bent. The rising concern of bamboo about
rapidly depleting resources is fuelling a bamboo revolution of sorts as this
simple species of grass is being used. Some architects were aware of the finite
resources of our planet and devoted to invent sustainable buildings and
transportation for the people. Some was driven by the simplicity and
extraordinary strength of bamboo as a building component. Since bamboo is a
sustainable and quickly renewable resource, it then involves in construction
projects with pioneered new designs and construction methods for buildings of
all kinds. Some examples are Green School in Bali and Kayu Manis Resto in Bali.
The façade is one of the important components of a building. Not only
does it give an identity to a building but it also plays the vital role of
acting as an interface between the interior space and the exterior (shown in
Figure 1). However, another factor that affects interior and exterior comfort
is the climate. The climate relates to solar heat or solar radiation,
temperature, wind flows, rainfall, humidity and topography. In the climate
issue, temperature is the most important thing to be considered, this is
because temperature mostly refers to comfort which is influenced by other
climate factors. This paper uses bamboo as the constant façade material to
experiment its performances in various climatic conditions. These are all
crucial in ensuring the well-being of the users of the building. The façade and
climate therefore determine how someone feels about a building from the outside
as well as a whole living experience within a building.
Bali Bamboo Wall
Bali region has tropical climate with 2 seasons, rainy and dry season.
The highest intensity of solar radiation is up to 502W/m²; the temperature is
up to 33ᵒC and the average relative humidity is between 70-86% per month. Since
Bali is located near the Equator, it means that daylight hours are consistently
12 hours. The primary concerns of the tropical climate in the warm humid region
are high temperature and humidity. It will need several strategies to prevent
negative impacts and to take full benefits from the climate’s positive impacts.
The main strategies are to provide maximum ventilation and shading to avoid
heat storage.
Tropical climates are hot and humid. Therefore keeping the heat of the
sun off is the top priority. Bamboo-structure building provides a unique screen
that protects the building from intense sun and provides a veranda. The windows
and prefabricated walls are so well insulated that the home’s primary sources
of heat are the occupants and the sun and a heat recovery ventilator provides
fresh air. The temperature difference between the exterior and the interior of
a bamboo-structure building averages 4-5 degrees on a hot summer day.
Bangladesh Bamboo Wall
Bangladesh has a subtropical monsoon climate characterized by wide
seasonal variations in rainfall, high temperatures of 36ᵒC and humidity between
63-83%.
Typically bamboo houses have bamboo mat walls with bamboo posts. Flood
with strong currents can destroy wall panels, get washed away and may be
partially or complete lost, especially if the connections to posts are weak.
Adequate number and size of perforated bamboo mat walls should be built orient
along the prevailing wind flow direction to allow cross ventilation. Currently,
the field study of Bangladesh traditional bamboo houses are done on several
number of bamboo houses at rural and suburban areas in Bangladesh. For
environmental study, temperature and humidity data are taken by thermal data logger
(HOBO). The initial finding of the thermal performance study of the traditional
Bangladesh bamboo house is comfortable at night in hot summer season. The
maximum indoor temperature is recorded 29.5ᵒC when outdoor temperature is 29.95ᵒC.
Indoor minimum temperature was recorded 26.6ᵒC when outdoor temperature is
27.12ᵒC. The indoor temperature is always lower than outdoor space. The
difference between indoor and outdoor temperature decrease because of heat
starts to transmit from hot spaces to cool indoor living spaces. According to
this phenomenon from the tabulation, it is indicated that it has sufficient
difference between indoor and outdoor temperatures.
Yunnan Bamboo Wall
The climate of Yunnan Province is warm, rainy and humid. The annual
average temperature is 21ᵒC. The average temperature is comfortable so there is
no strong demand for thermal and protection from heat. The main concern is to
avoid the humid ground. The Dai area in Yunnan has an abundant rainfall amount
which means the moisture on the ground level of a ordinary house is relatively
higher than the other areas in China. Bamboo buildings have much lighter weight
than the traditional and typical brick structured buildings in North China.
Bamboo in Yunnan has a large productivity among local plants and the growing
speed and productivity is much more considerable than timber. To be advance,
the wall of stilts houses are covered by weaved bamboo strips. The gaps between
the strips make it possible to let wind blow into the indoor space, which can
be considered as a pattern of passive ventilation. Since bamboo has a strong
adaptability to different climate, it is believed that bamboo as a material
itself would not be easily changed in physical quality. Also, the Dai area of
Yunnan is close to the edge of tropical area and locates in the arm and flat rural
area in mountain district, so that bamboo as a main building material is
excellent in consider of strength and budget reason.
Chennai, India Bamboo Wall
Chennai is located on the South-Eastern coast of India and is the
capital city of the state of Tamil Nadu. The weather in Chennai is hot and
humid for most part of the year. Extreme variation in seasonal temperature is
prevented due to its location on the thermal equator and the proximity to the
coast. The temperatures during the day is between 35-40ᵒC and around 20-32ᵒC
during the nights. The relative humidity is high throughout the year with
values higher than 80% during the nights and early hours of the day. During the
day, the relative humidity is around 40-60%. According to studies carried out
in India, the limits of thermal comfort is said to vary considerably. The
thermal comfort of a person is said to lie between 25-30ᵒC with optimum 27.5ᵒC.
The bamboo design proves that thermal comfort for a large part of the year can
be achieved by improved air movement within the building. High rate of natural
ventilation will lead to a situation where the indoor humidity levels follow
the outdoor condition. Relative humidity was not considered in the current
study as literature study shows that high humidity, especially in hot-humid
climate will not affect thermal comfort as the users will be accustomed to it.
The bamboo design manages to achieve a ventilation rate that is more than
required by the standards, hence this criteria has been addressed adequately.
Continuous air flow within the room should help achieve a reasonably good
quality of air.
Western Europe Bamboo Wall
The environmental performance of bamboo used in Western Europe highly
depends on the form in which it is used. In its natural form (the culm), in
several applications, bamboo process more than 20 times as sustainable as the
common western building materials timber, steel and concrete. When used as an
industrial product such as wall panel; the environmental advantages of the
bamboo culm are lost. Compared to most wood-based alternatives, the
environmental performance of the assessed bamboo panel is slightly less
favourable. Nevertheless, with some adjustments in the production process, a
non-bleached sustainable alternative of the bamboo panel is possible.
Furthermore, by applying a bamboo panel, technical problems related to the
geometry of the culm can be avoided. Still, when choosing bamboo for its
sustainability, it is recommended that the culm should be used.
Practical problems when using the bamboo culm in Western Europe are
numerous and have a couple of bamboo-related main sources: the shape of the
material, the irregularity of the material and the lack of knowledge and
building codes. Many of these problems can be avoided through centralisation of
knowledge and development of bamboo building codes. Therefore, many problems in
future bamboo projects in the West can be avoided, thus saving time and money
while upgrading the quality of these projects. Bamboo is a natural product with
irregular shape. It is therefore suggested to be used in temporary buildings or
play a role as a finishing material.
Conclusion
This vernacular architecture has grown out of simpler forms of
indigenous building as done by more primitive cultures, and usually includes
the same set of climate responsive parameters and similar materials but using
somewhat higher technology in the construction. It has been built to reduce the
range of local climatic variations; to avoid some of the heat of the sun in hot
climates, to welcome the breezes when they can provide desired cooling and to
admit light in sufficient amounts for task lighting and to keep out excessive
or unnecessary light. Bamboo, as an alternative building material, helps in
decentralizing the construction process which has both economic and ecological
advantages; to control environment conditions for human comfort.
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