To what degree can bamboo
technology control the environmental conditions of interiors and semi-interiors
compared to industrial building materials?
Introduction
From the external perspective, as objects for the eye of a distanced
beholder, bamboo buildings appear first as works of art, as arrangements of
volume and void and colour, as sculpture. The eye is pulled by the building’s
appearance into its plan into its use; emphasizing the most important
dimensions of buildings lie inside. The experience of the interior makes the
provision of internal spaces to shelter people and help them order social
occasions. None of these developed in
extreme climates.
We humans have desire a certain minimum level of comfort inspite of the
weather or location. The major elements of climatic environment which affect
human comfort are air temperature, air movement and humidity through our bodily
heat transfer of heat gains and heat loss and noise level. Therefore, shelter
is the main instrument for fulfilling the requirements of comfort. It modifies
the natural environment to approach optimum conditions of livability.
The building envelope is the physical separator between the interiors
and exterior of the building. Components of the envelope are typically walls,
fenestrations, roofs and floors. In this paper, a brick-concrete building is
selected as a baseline with the same floor area and window ratio as the bamboo-structure
building; is compared to distinguish intrinsic differences of the technical
potentials of the environmental conditions of interiors and semi-interiors.
Thermal Insulation
Envelope insulation being assessed through energy use and carbon
emission is identified within the boundary of the functional requirements of
the building.
According
to Dongwei Yu et. al., they indicate the bamboo-structured building has an
embodied energy or carbon of 3003.4Mj/m² and a thermal resistance of 168.9kg
CO₂/m²; in contrast to having a brick-concrete building of 3532.90Mj/m² of embodied
energy used and 326.1kg CO₂/m² of thermal resistance.
Wind Pressure
Roof with walls that pass breeze but not rain is the
most ideal for building by maximising natural ventilation. Both positive and
negative pressures occur simultaneously when wind interacts with a building. The
differences between a bamboo-structure building and a brick-concrete building are
the open eaves and porous bamboo slats for walls and floor that maximize natural
ventilation. The most extensive use of bamboo in construction is for the walls
and partitions. They are the major elements that carry the dead load and live
load of the building. An infill between framing members is required to complete
the wall to protect against rain, wind, animals; and to provide in plane
bracing to ensure the overall stability of the overall structure when subjected
to horizontal forces.
Wind can cause an increase or decrease in pressure within the building. Internal pressure changes occur because of the porosity of the building envelope (eg, openings of doors and windows, air infiltration through walls that are not absolutely airtight).
When a building is pressurized, the internal pressure pushes up on the roof. This push from below the roof is combined with the suction above the roof, resulting in an increased wind load on the roof. The internal pressure also pushes on the side of the rear walls. This causes the roof cover damage (eg. Metal edge flashing lifted) and window damage (eg. Outer panes of windows broken) occur due to the pressure of the aerodynamic forces. The monitored wall section was subjected to air pressure differentials, outdoor-to-indoor, within ±18 Pa, which is typical for most brick-concrete buildings.
When a building is depressurized, the internal pressure pulls the roof down, reduces the amount of uplift exerted on the roof and pulls in the windward wall, which increases the wind load on external wall. Therefore, the air pressure differential outdoor-to-indoor reduces to the range in between -9 to +2Pa.
Solar Shading
Acoustic
Bamboo-structure building is also a sound barrier that
drowns out noise. But, the screen must be dense and at least 3 to 8 feet wide;
thus depending on the cause of the noise. According to forestry experts, bamboo
has a reflection, absorption and blocking effect to sound wave. It can greatly
reduce noise level by 10-15 dB. Therefore, bamboo-structure building creates a
unique sound environment and soundscape. But brick-concrete building has a
higher noise transmission loss of 32-36 dB. It is already known for its
specified for noise barriers. According to Anderson (1984), Effects of
vegetation on human response to sound, a 10 dB reduction makes a sound appear
to be half as loud as our human ear does not perceive sound in a linear way.
Therefore, bamboo-structure building is sufficient to reduce noise at the
surroundings.
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.
