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Timber for Low Impact Buildings
--Material for Low Impact Buildings
Name: Chenlu Ouyang
Course: ARC6821
Tutor: Lucy Jones
Registration No: 110118622
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Timber In Low Impact Buildings
—— Materials for Low impact Building Essay Type B
Abstract:
The climate change and energy crisis require more sustainable
buildings than before. Timber is a traditional building materials
which is eco-friendly and sustainable and can be used for the
modern sustainable architecture. This essay describes some of the
traditional and modern ways constructions of timber buildings.
Then discuss the possibilities to adopt this material in my
hometown of Hunan Province in China.
Key words: sustainable, local, renewable, recycle, climate
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Introduction:
Due to the climate change and energy crisis, now “sustainable”
has became the theme of this time. Architecture is one of the
important part of energy consumption, and it needs to be much
more sustainable than before. Some modern materials such as
concrete and steel seems can not meet the requirement of
sustainable. In order to minimize the environmental impact of the
buildings, by embodying the low impact building materials is very
helpful especially in minimizing the energy and carbon dioxide
emission.
There are many kinds of low impact building materials such as
straw bales, rammed earth, compressed earth blocks, hemp-lime
blocks, timber. In this essay I will discuss timber as a material for
low impact building and also discuss some new technology of
timber construction and the management of the manufacture for
timber and timber component.
General description of timber:
Timber is one of the oldest building materials which has been
widely used worldwide from ancient time. It is a natural, renewable
material and very easy to use. Timber products can store more
carbon dioxide, and will continue to store it throughout their longsevice life, than the carbon dioxide emitted during their process of
manufacture.
According to the natural characteristics of timber, it is strong in
both tension and compression and has a high strength to weight
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ratio. Almost any size of design structure can be made by timber.
Another important characteristic of timber is that it is light and
versatile, so it can be used not only for the structure, it can also for
interior or façade, including framing, lining, cladding, flooring,
roofing, covers almost every parts of buildings.
Traditional use of timber:
The use of timber in architecture can be dates back to thousands
of years ago. In China, timber structure was in the dominant
position for ancient times and used extensively in traditional
architecture. It starts from the house in the southern part of China
that has a humid climate and rich in timber resources. Then
different
form
of
the
timber
buildings developed and been
widely used in different kinds of
architecture such as palaces and
temples. This may due to the
traditional Chinese philosophy
that the ancient Chinese believes
in reincarnation, and timber is
the kind of the material that has
an endless cycle and represent a
symbol of eternal life.
Though
compared
to
stone,
timber is weaker in ruggedness
and durability, and it will also be
Ancient timber structure of China
limited in the natural size of trees.
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So the ancient timber buildings were usually one or two stories.
While the craftsman has developed a construction system to make
full use of the flexibility of timber. The main structure of timber
building was beam and column system, the main loan-bearing part
is the column and beam, the wall works just as the retaining
structure. In this way even though the wall falls down, the building
will not collapse. This endows the building a good seismic
performance. A complete set of timber construction system has
been developed after thousands of years. At the same time, a
module co-ordinator system is developed. Different components of
the timber structure were made according to the specific module.
Mortise and tenon:
The most common traditional construction techniques for timber
architectures is the mortise and tenon. This technology may be
developed because of the natural characteristics of easy to cut and
handle of timber.
The most simple and basic mortise and tenon
Generally, the mortise and tenon joint is the method to join timber
by working a solid rectangular projection in the one piece and
cutting a corresponding cavity to receive it in the adjoining piece.
There are different kinds of mortise and tenon, and in China, this
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technique has been developed to extreme, it is not only for the
purpose of structure, but also a way of decoration to show the
natural beauty of timber.
Modern use of timber:
The development of timber architecture had been stopped for a
period of time. This may due to the development of technology and
the contemporary construction especially after the industrial
revolution, new material such as steel and concrete has become
the main building material. Another factors is the deforestation
caused by inappropriate logging that prevent the development of
timber construction.
But great quantities of energy or other resources will be consumed
during the process of the modern construction operation and
eventual demolition of buildings that is made by some modern
materials. Take steel as an example, the manufacture of steel
burns non-renewable fossil fuels and releases about 2 tonnes of
carbon dioxide for each tonne of steel produced.
With the increasing awareness of environmental issues, such as
the energy crisis and climate change, much more concern has
been made to the environmentally sustainable development,
especially into the environmental performance of buildings.
Timber, which is readily available and easy to work can be
redeveloped as the sustainable and natural building material for
modern architecture. Another advantage of timber is that it can
store the carbon and has a low embodied energy.
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Obviously, the traditional way of timber construction can’t meet the
requirements of the modern needs, and some natural weakness of
timber should be overcome. So some new technology of timber
developed.
One important progress of timber construction is that to combine it
with some other modern materials. For example the joint of timber
now has combined with steel component to make it more stable
and have a better seismic performance. The timber component will
have a series of special to enhance the ability of fireproof,
moistureproof and anticorrosive.
In traditional timber buildings, the majority way to use timber was
to use it to make the framework.
While the function and form of
modern timber has become more
diverse than ever before such as
timber panels, timber strings, etc. It
can be used in different aspects of
buildings. In the large commercial
building of One Omotesando which
was designed by Kengo Kuma, the
structure is made of steel, the timber works as the decoration both
interior and exterior. In this way , nature has been bring to the
urban space. The purpose of this project was to relocate the
sociation in Tokyo, in order to better display the various
possibilities of timber, and in the hope of reviving its popularity as
an urban construction material.
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Prefabrication of timber:
The traditional way of timber construction is mainly handcrafting. It
is
extremely detailed,
and needs
exacting precision and
craftsmanship. But this way of manufacture which needs intensive
labour and will take a long time that can’t meet the requirement of
modern timber construction. One of the solution is that to automate
the production process, it is also very important to continue the
timber construction. To use the precut technology for timbers,
crafting the holes, pegs, and jointing by modern machinery for
frames in the building industry. The precut system produces
accurate sized timber frames. Logged woods warp, twist and
shrink when moisture evaporates.
One of the successful examples of the prefabrication timber house
is the Japanese Onjuku beach house. It is a example of the fully
automated technology. It was erected only in 1 day by a small
construction team led by two carpenters.
It all starts at the factory, where the architectural drawings are
turned into shop drawings that the computers can read. From here,
the raw wood goes through a series of mills and routers, labeled,
and finally packaged for shipping off to the site. Once the wood
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pieces
arrive
at
construction
the
site,
the
collection of milled beams
and columns can be read
and assembled like a puzzle.
Mortises
and
together
perfectly
allows
joints
tenons
to
fit
which
be
fully
exposed and embraced in
the architectural aesthetic of
the
building.
Furthermore,
this method preserves the
age-old tradition of detailing
and construction with wood
for
future
generations
to
appreciate. ( www.archdaily.com )
The life cycle and forest management:
In order to make timber
to be a truly renewable
material, a new lifecycle
and forest management
should
The
be
trees
developed.
will
be
harvested to exploit their
wood, and have to be
Life cycle of timber
replaced by growing new
trees that will in turn, grow and absorb carbon dioxide. In order for
this, it requires management of the forests in which timber grown.
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Once a tree or forest has reached its limit it can be harvested, the
carbon remains stored in any products produced whilst new tree
can be planted allowing further carbon dioxide to be extracted.
Europe has managed to reverse the issues of forest depletion and
is actually increasing its forested area by approximately 650,000
hectares a year. This is thanks to successfully executed legislation
that demands forest owners to replace harvested trees, as well as
the Forest Stewardship Council [FSC] who promote the
responsible management of forests internationally.
Recycle and Reuse:
Recycling and reuse capabilities are one factor that contributes to
the great potential of timber to reduce the amount of construction
waste going to landfill.
Another benefit comes during the construction, using timber, as
different from using concrete, results in no wet trades, and the
associated waste, on site. It is also possible that all the timber
used in a project can be pre-fabricated in the factory as mentioned
before which means that there is possibly no timber waste
production on site. Any waste created in the factory can be
efficiently recycled or reused.
Besides, timber used in construction has the potential to store
large amounts of carbon, therefore the longer the timber is kept in
use the greater the carbon stored in it. Therefore this requires any
timber products to be reused and recycled wherever possible. For
recycling and reuse of timber to be most effective this requires
most consideration at the design stage, not just once a building is
demolished. Using the specific module may do great help. We
need to be aware that one day the building will become available
as a material stock for potential reuse or recycling.
There are three ways timber can be used after its initial use, that is
material recycling, energy use [as biomass], and biological
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decomposition.
Another reason for carefully designing and detailing of timber for
reuse is that: The demand for services and housing will change a
lot depending on the changing circumstances and development of
the society which requires buildings to be more flexible and
temporary.
We can draw a conclusion that, make timber component able to
recycle and reuse is one of the most important aspect to develop
sustainable timber buildings of low impact.
Timber is Hunan Province:
Timber has been used as the low impact building materials in
many countries and many places, and there are many successful
examples. While in China, where the timber was in the dominant
position of building material for thousands of years, is it possible to
reuse timber as the building materials in a new sustainable and
eco-friendly way? Then I will take my hometown Hunan Province
to discuss how to revival and develop this building materials.
Overview：
Traditional timber construction has been highly developed in
China，but it has been replaced by some modern materials such
as concrete and steel.
With the sustainable requirements of
buildings, timber should be reused and redeveloped in some area
of China. The modern timber architectures has been developed
successfully and been widely use in UK, Japan, Australia, etc.
According to some survey, 47% of the new built house and 20.7%
of the UK new built house were timber house. This evidence
indicates that the traditional material can be revival after modern
technology and construction which we can get some successful
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experience from them, especially on the lifecycle of timber, forest
management and prefabrication techniques of timber.
Hunan Province located in the hilly area in the middle-south of
China. Also this is an area of continental sub-tropical monsoon
climate with four distinctive seasons and abundant in rainfall. The
weather is humid especially in summer. One of the main tributary
of Changjiang River flows across the region and there are
numerous rivers and lakes in Hunan. The climate contributes to
the growth of trees and the forest resource is abundant in Hunan:
the forest coverage rate of Hunan has reached 57.1% these recent
years. Many timber factories has been set up near the forest and
woodland of Hunan Province, which endows this area the potential
to develop new timber industries and timber construction.
As belonging to the traditional Chinese timber construction system,
Hunan has a long history of using timber as one of the local
material as well.
Besides, timber is not only used of building
material in Hunan, but also can be used in different areas. For
example, the timber furniture , the craftsmanship of the carving on
the timber and the mortise and tenon of the joint has developed to
extreme. Now the timber furniture is still very popular among local
people. Some infrastructure are also made by timber as well, such
as the timber bridge, and timber leisure facilities.
Traditional timber buildings of Hunan:
The timber buildings of Hunan started as the stilted style house,
which looked like a bird’s nest that can protect the local people
from the beast attack and the humid ground. Then after years of
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experience, a unique local construction techniques and timber
culture has been developed.
The form of the timber buildings was developed because ancient
Chinese focus a lot on the combination of the climate into
architecture. Chinese believe that the nature and human beings is
a integrated whole part, this idea was also reflected in the
buildings and the organization of the garden and buildings. A
series of theories about the climate and architecture has been
developed to work as the guide of the architecture construction
such as the location of the buildings, the directions of the buildings,
etc.
The
most
common
form of the buildings in
Hunan is the garden
house. This form is
developed according to
the characteristic of the
local
climate.
Since
Hunan has abundant
rainfall, in the typical
garden house there will
be a pool in the inner
garden in the middle of
the building. The gradient of the roof is quite deep than the house
in north China, the slope of the roof is towards the inner garden,
the rainwater will run into the pool rather than remain on the roof. It
also do great help to the ventilation of the house, especially in
cooling down the house in the hot summer.
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Another
interesting
prototype
of
the
timber
house in Hunan was the .
This
prototype
was
developed from the original
stilt style architecture. The
formation of this hanging
house is the combination
the
local
climate
and
topography into the form of
house.
is
because
the
humid weather of this area.
To elevate the ground floor
by stilt could protect the
buildings from the humid
and wet ground especially
Hanging house of Tu-ethnic
in spring. At the same time
this form can also prevent
some insect from destroy the building. The elevated structure can
improve the ventilation as well. This special form of house has
been developed in many areas of Hunan province especially at the
riverside or in the hilly area. This type of house is totally eco-house
that makes full use of the local nature resources, combine timber
with local stone and brick. It shows some of the ancient
sustainable and the willing to keep in harmony with nature of
ancient Chinese.
There is a traditional concept that to make full use of the material,
from large panels to tiny piece of fragment. The ancient Chinese
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has put great importance in stay in harmony with nature that we
should learn a lot from that.
Development Prospects of the Timber Buildings in Hunan：
The modern urban development has ignored some of the local
culture and local context. Overusing the modern construction and
modern material has caused many problems not only in
environmental aspects but also in the local context. In Hunan, the
speed of development is so fast, many highrises and modern
architecture made of steel, concrete and glass has been
constructed in these decades. In order to make space for the
modern architecture, many hills and valleys has been made flat,
which made the local topography being totally destroyed.
The
micro-climate of the urban area has become not that confortable
for people to live in. Also some air pollution and energy crisis made
this situation much worse.
By redevelop and reuse the timber buildings could be one of the
way to solve these problems. For example, take full advantage of
the special and unique prototype of the local hanging house could
be a great way to protect the existing slopes. The local context
could also be brought back by the revival of some of the traditional
architectural language by using the timber. Combine the traditional
construction techniques with the modern technology and materials
to make it more stable and have a better seismic performance. At
the same time overcome some of the weakness of the timber.
Though it is not realistic to make all types of architecture by timber
especially of some large-scale architecture. But it is possible to
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start with some small-scale buildings such as timber residential
buildings at the suburban area which is close to the forest and
nature woodland. The prefabrication manufacture of the timber
component can be introduced into this area, set up a module
system for the timber manufacture could also be a way to recycle
and reuse some of the timber component. Another important and
helpful aspect is introducing the proper life cycle and forest
management that has been mentioned before and develop a
system of a recycling and reuse circulation of the timber materials.
In this way, some of the existing problem about pollution and
climate change might be relieved to some extent. Then with the
development of the timber construction technology, the carbon can
be stored into the fabric of buildings which is the sustainable and
eco-friendly way.
Conclusions:
From the discussion above, we can draw a conclusion that the
modern use of traditional material--timber as the building material
is a sustainable and eco-friendly way to deal with some problems
of climate change and energy crisis. By proper develop
appropriate timber life cycle and the forest management and
prefabrication of timber, it is possible to recycle and reuse of the
timber products, and make it totally low impact and sustainable.
This modern way can also be used in some area in my hometown.
With the help of some of the existing successful experience, by
combining the traditional form of timber house with the modern
techniques could bring new life to the local buildings in Hunan
Province.
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References:
Website:
http://www.archdaily.com/158918/japanese-precut-timberconstruction/
http://oak.arch.utas.edu.au/tbia/article_srch_topic.asp?area=env&t
opic=14
Fu, Phobe and Chapman, John. (2007) Timber Design Journal. Vol 12,
Timber in Ancient China.
Lin, Xiande. (2007) Green Architecture[M]. Beijing, Industrial
Architecture Press.
Zhao, Guangchao. (2006) Buzhi Zhongguo Mujianzhu, Shanghai,
Shanghai Science and Technology Press.
Shan, Deqi. (2004) From Traditional Residential House to Local
Architecture, Beijing, Industrial Arhictecture Press.
Huang, Jiajin and Qiu, Canhong. (2006) Hunnan Traditional Residential
House, Changsha, Hunan University Press.
Lu, Jiansong. (2008) Research on Timber Architecture in Hunan hilly
Area, Changsha, Hunan University Press
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