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Abstract.
No other material displays the true character of a sustainable resource
more convincingly than wood. Forestry and modern wood technology, therefor,
deserve high priority in the development of mountain regions. As a
renewable, natural product wood presents an impressive spectrum of unique
properties. Its application as universal construction material and energy
supplier offers a tremendous economic, ecological and social potential.
Yet, forest growth by far exceeds wood use in alpine countries such as
Austria, Switzerland the Bavarian Alps or Slovenia. This paper focuses on
innovative wood use as construction material in alpine regions. The
examples, however, can only reflect a small fraction of the considerable
and still not fully appreciated potential of wood in sustainable
development.
1.The economic and social significance of wood in alpine regions.
Wood has an enormous economic and social significance for European
mountain regions , as illustrated by the Austrian example:
- Wood is Austria´s most important export product. In 1996, Austrian
wood exports represented roughly 4 ½ Billion €.
- 7000 energy centres in Austria utilise wood as an energy resource,
generating 22. 000 jobs for the installation, use and maintenance of
thermal power stations, covering an estimated 10 % of Austria´s
energy requirements
- A significant part of Austrian Economy relies on medium and small
size companies engaged in such fields as logging, wood building and
construction, wood furniture, or the pulp and paper industry. The same
accounts for other countries with large forested alpine areas such as
in Switzerland, Italy, Germany, France or Slovenia.
2. The ecological significance of wood.
The tremendous significance of our forests has fortunately been recognised
in European alpine countries, Their vital function as filters for clean
air, for the protection of water reserves and balance, their contribution
to the prevention of erosion, landslides, avalanches, rock falls or
inundation, and, last but not least, their contribution as habitat for
species and securing biodiversity is self explanatory and not subject of
this paper. As far as wood itself is concerned, three ecologically
relevant aspects should be kept in mind:
- Even though the Integrated CO2-balance of wood still leaves some
room to scientific dispute, it can be maintained that wood as a
renewable raw material is in essence CO2-neutral. The wooden Roof of
the Expo 2001 pavilion (now a protected wood monument) in Hannover
stores 1.200 tons of CO2 for the next century
- Wood can easily be recycled or alternatively, it can finally be used
as a valuable source of energy.
- Wood growth is tremendous: In Austrian forests it amounts to 1 cubic
metre per second, (in Switzerland for comparison 0,3 cubic metres per
second)!
3. Problems and drawbacks impeding wood use.
Notwithstanding excellent prerequisites as a source of highly qualified
technical material wood has to cope with considerable handicaps:
- European forest volume increase is higher than the increase in
domestic wood utilisation. Forested Surface in Europe has gone up from
175 million ha (1960) to above 200 million ha at present. Only 70 % of
wood growth increase is used in Austria, and not more than 60 % in the
rest of Europe.
- Within the quantities used, the predominant part of wood is utilised
for low priced applications and only offers a very modest added value.
- Despite considerable innovative progress achieved in wood
application technology and particularly in technical construction,
companies involved in large scale wood construction, wood bridge
building, private wood house dwellings or other applications still
deplore considerable prejudice against the utilisation of wood as an
alternative to brick, steel, concrete or plastic.
- The situation described is similar in practically all alpine
countries.
What are the reasons responsible for such a development, and what can
be done against it? To generate appropriate answers, ALPENFORUM carried
out an inquiry last year, providing interesting answers and viewpoints to
the questions posed. It is, however, not the purpose of this paper to
elaborate on details of this survey. One essential conclusion however
should be stated at this point: Public opinion clearly reflects a
remarkable deficit in proper judgement concerning the merits and
shortcomings of wood as construction material as compared to brick,
concrete, steel or plastic. Fire hazard attributed to wood, for instance,
is generally overestimated. Similar prejudice accounts for durability and
a number of other performance parameters. On the other hand, existing
shortcomings of wood constructions, such as unsatisfactory wind tightness
or humidity diffusion, may frequently be overlooked.
This situation given, intelligent marketing strategies based on sound
information and communication are paramount for a better public
appreciation of wood use. The results of our personal interviews signal
heavy shortcomings in this respect. Though considerable efforts are
presently made to alleviate the problems involved, there remains a lot
more to be done. It is interesting to note that the Austrian
Delphi-Report, when elaborating on the innovative use of wood and its
perspectives, arrives at quite similar conclusions.
4. wood construction technology and innovative application
Our alpine ancestors have developed characteristic versions of wood
architecture and a sophisticated knowledge of wood construction and
engineering. Wood in alpine lifestyle played a key function. Dwellings,
barns, bridges, churches or even fire stations were built of wood, which
was considered as an easily accessible and highly satisfactory indigenous
resource. Centuries ago it was realised that wood should be cut when low
in water content, and properly dried prior to processing. Buildings made
of wood in this manner proved stable and stayed that way an amazingly long
time. Much of this knowledge, unfortunately, got lost in the course of the
last century. Concrete, steel or plastic more and more replaced wood.
Prejudice voiced claims wood to be less durable. This certainly has
something to do with more modern, less time consuming lumbering practises
and the increasing disregard of seemingly old fashioned forestry and age
old wood technology experience. More recently, however, a change of mind
can be observed. Wood is regaining popularity, almost lost experience is
revitalised. Modern pioneers in wood application are combining sound wood
experience with modern technical concepts, other construction materials
and sophisticated solutions
The key answer to success in modern wood house construction is the
combination of comatible construction material, attractive architectural
design, high quality and functional performance . These are the essential
prerequisites to generate both market acceptance and added value required
The following examples present a small selection of such more recent
developments.
4.1 "Massive wood"
Modular construction elements and a high prefabrication status
characterise the predominant tendencies in modern wood building. The high
stability of such elements allows even multistorage construction. It has
become apparent that conventional blockwood construction does not meet
modern housing requirements satisfactorily, and upright housing, therefor,
has gained reputation.
One of the newer developments in this context is the so called massive
wood element ("Holz 100" ). The Thoma wood construction campany
in its Goldegg Research centre, developed a simple, yet ingenious system:
Upright wood posts are arranged in several layers and a compact manner
without interstitial space. A calculated screen of dry wood dowel pins
treated with natural casein glue penetrate the wood elements with great
pressure. The pins absorb residual moisture within their new location and
swell, irriversibly compounding the element parts. The final element
corresponds to a monophase structure, 100 % wood. Such elements are
extremely resistant against damage, mold or condensation. They are highly
wind- and waterproof, expel excellent thermal insulation- and sound
attenuation properties. The same accounts for protection against high
frequency radiation. This type of wood element is practically the only
material able to carry a multistorage house and at the same time achieve
the insulation values required for a .low-energy house (k-value 0,22
W/m²K) without the aid of additional insulating layers. Massive elements
for upright construction do not generate condensation problems and are
extremely effective insulators with correspondingly high k-values. This
can be explained by imprisoned air cushions in the interior of the rough
wood structure.
Another feature of such massive elements is their excellent flame
retardant property. Elements with 40 cm width can accomplish flame
retardant properties above F 90. After flaming for 150 minutes, the
element has still regained its full bearing strength. Collapse of ceilings,
as observed with concrete, never takes place with such wood elements.
After 60 minutes temperature exposure at 900 °C, the backside of this
massive wood element displays a temperature increase of merely 3 to 10°
C, a value far better than the F 30 required . Anybody questioning the
durability of such constructions should remember that wooden Japanese
temples are more than 2000 years old and still perfectly intact!
An alternative concept to achieve improved wood performance is the
KLH-system. Wood boards are positioned and glued crosswise, thus obtaining
massive elements that are easily assembled to larger wall or ceiling
modules. Insulation and stability is less favourable than obtained with
wood elements as described previously, but perform better than ordinary
wood constructions. The system allows for improved load distribution in
every direction and time saving assembly.
4.2.Room climate
Another important feature of wood dwellings is their (interior) room
climate. Massive elements perform very well because of their high
insulating value (10,0 - 0,1 W/m²K) combined with their high specific
density (400- 500 kg/m³) .
4.3 Security
When studying modern wood construction developments, an amazing spectrum
of innovative applications are encountered. Security is an example. The
Freisinger wood company in Tyrol developed a highly successful
anti-burglary system for its wood window panels. Essential features of
this system are: Strengthened, multiplied lock bolts, solid screw joints
for all fittings, reinforced glass panels, careful assembly. Freisinger´s
"Antiknack" window panels withstand rough handling with
pointweights up to 300 kilos, 80 kilo sandbag drops from 80 cm height,
professional burglary efforts with wedge gibs, screw drivers or pliers, (standard
test period 3 minutes). It is assumed that the occasional burglar will
then give up his efforts and possibly try his luck elsewhere.
4.4. Energy saving
Still another aspect concerns energy saving. So called low energy houses
do without separate heating systems under the windows. This is only
possible with heat transmission coefficients of such windows below 0,8
W/m²K. Freisinger´s wood window system meets this requirement by using
in its window panel an inner layer responsible for the complete window
function itself, a middle, non carrying cork insulation layer and an
exterior, protective layer, which is easily removed by twisting, and can
be either repaired or exchanged whenever necessary. Windows in wood can
display a remarkably esthetic appearance . The exterior layer mentioned is
made of larch, pine or oak, all durable wood types that require little
surface treatment or none at all.
The so called solar facade is another energy saving wood element. The
module is mounted on a post-bar construction. The range spacer between the
exterior wood layer and the post-bar is thermally separated and consists
of a wood fibre insulation and wood carrier. The glass pane weight is born
by statically calculated glass clips.
4.5. Protection against electro smog
A technical development in Southern Germany (Baufritz wood company ,
Allgäu) concentrates on wood dwellings protected against Electro-smog.
Ubiquitous cell phones, high voltage power lines, transformers, radar
stations, electric train ducts or mobile wireless facilities, all of these
and many others can generate radiation. Science, so far, is not in a
position to clearly assess the possible human health damage caused by
electromagnetic exposure. As protective or at least preventive measure,
Baufritz developed a panel of natural gypsum lined with a thin layer of
carbon. These panels can be installed against wooden walls or roofs and
earthed. Measurements at the German army´s university in Munich confirmed
high frequency radiation screening up to 94 %. Massive "Wood
100", as a matter of fact, equally displays similar or even better
screening values, as found by recent measurements at the already mentioned
institute in Munich.
5. Final remarks
Wood innovation and architecture, design and technical application is
the pride of numerous developments. The construction examples given
illustrate the value of "niche"-services in sustainable wood
development and the marketing strategies required to promote such a
development. Wood compounds, wood houses or other wood facilities are
steadily gaining reputation
- The community of Murau built the largest European wood bridge).
- Production facilities in different regions of the Alps have been and
are constructed.
- Functional premises such as fire houses have regained
popularity.
- Modern, well built wood houses promote the quality of life for an
increasing number op people.
- The expansion of Health centres or solar facades .
This is encouraging. If sustainable development is our choice, then by
all means we should support and promote the use and innovative application
of wood.
St. Georgen ob Murau, Austria
Dr. Ian c. Meerkamp van Embden
Tel.: 0043-3537-20020
Fax: 0043-3537-20022
e-mail: ALPENFORUM@t-online.de
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