Introduction

If science is a theoretical approach to understand nature, construction is a practical approach to make the most of what we have in nature. In this way, construction is a moment we face directly with nature, our environments as they are. Thus we build things: it is an artificial set-up to confront and reconfigure the essence of design.

Construction in this module is not such as to take whatever materials at hand and build whatever we want, but it puts emphasis on making the most use of materials, this case zurich specific yew tree, and come up with smart use of them within specific duration and cost. Therefore we need to negotiate with these constraints in construction, and decide the way to maximize materials, construction processes and design solution.

Certainly construction is not only allowed for human being but for other species. For example, beavers construct dam (the biggest length is 1.8km) infrastructures out of irregular tree branches, and even sometimes they transform natural environments. Also ant is another genius in a smaller scale. From the tectonic points of view, only thing differentiating human being from any other could be the notion of standardisation in construction.

Standardization was a modern material production placing importance on efficiently producing uniform, homogeneous artefacts from natural, irregular materials. With the aid of contemporary design techniques however, it is now possible to have material design make use of, and even feature explicitly, the imperfections of natural materials with minimal impact on production efficiency. Through the use of digital scanning and robotic fabrication, proposes to take material irregularities as design input, to distinguish and create meaningful order from material ‘noise’. Instead of materials adapting to production processes, it is an inversion: construction adapting to materials, from top-down design to bottom-up design.

 

Organization of the module

The module consists of three phases:

1. Individual design development for the assignment (1-2w)

2. Design selection and detail design development (1w)

3. Construction (3-4w)

 

Ingredients for design assignment

The material (yew), construction facilities as well as technical challenge, design subject and cost/time constraints are described as followings.

Material: Yew

The yew is a small- to medium-sized evergreen tree, growing 10–20 metres tall, with a trunk up to 2 meters  diameter, but usually 20-40 cm. It is relatively slow growing, and can be very long-lived, with the maximum recorded trunk diameter of 4 metres probably only being reached in about 2’000 years.

Yew is especially associated with Wales and England because of the longbow. Yew was the wood of choice for longbow making; the bows are constructed in such as way that the heartwood of yew is on the inside of the bow while the sapwood is on the outside. This takes advantage of the natural properties of yew wood since the heartwood resists compression while the sapwood resists stretching. This increased the strength and efficiency of the bow.

Today European yew is widely used in landscaping and ornamental horticulture. Due to its dense, dark green, mature foliage, and its tolerance of even very severe pruning, it is used especially for formal hedges and topiary. Its relatively slow growth rate means that in such situations it needs to be clipped only once per year. The slow growth is also fatal to the yew. The young trees are chewed by deer which are immune to the poison. Therefore the yew is a protected tree that is almost extinct in the forest.

 

The Zurich tree

At Zurich’s Uetliberg thrives the last great refuge of 80’000 European yew (as much as throughout Germany). Why just in the Albis, Uetliberg area? Thanks to Napoleon, after the French Revolution hunting was not restricted in the forests around Zurich. With the result that in 1860 the deer was almost eradicated. A great time of yew began and most of the Uetliberg yew are from that time. While in most parts of Europe yew is almost extinct and strictly protected, yew from Uetliberg is available at a reasonable price.
But as yew dropped out of the international wood market, there is no domain for this highly capable wood – it is used for securing the Uetliberg infrastructure (e.g. poles, stairs, timbering), but not in construction or carpentry. Zurich faces the situation to offer in comparatively large amounts a kind of wood that cannot be found anywhere else.

 

In short, the yew can be characterized as follows:

• toxic (except the bright red aril surrounding the seed)

• slow growth and longevity

• “wood defects”: knotty and twisted

• heartwood resists compression, sapwood resists stretching

• extreme color difference between heartwood and sapwood

• decay resistant

• local in Zurich

 

Assignment

The yew tree is a special tree with a local background that dropped out of the wood market.
The challenge of this course is to approach the yew with information technology, decide for one (or more) of its specific characteristics and make use of it. There is no defined task to do, tasks will develop from the research. Potential fields to work in are:

• Ornament 2D
  The twisted and knotty growth is very prominent in the surface of planar yew boards thanks to the color difference between the heartwood and the sapwood. It could be used for ornamental applications.
  Technology: 2D-scanning (or images)
  Reference: Bolefloor, Digitized grain

• Objet trouvé construction 3D
  3D scanning allows to catalog the twisted yew tree elements and develop computational means to apply the cataloged information to new design models.
  Technology: 3D-scanning (Kinect with ReconstructMe, PhotoScan, 123D Make)
  Reference: Smart Scrap, Serial Branches

• Structure
  Yew was the wood for longbow making with the pressure-resistant heartwood on the inside of the bow and the tension-resistant sapwood is on the outside. The small diameter, the twisted growth and the knots require a careful selection of material, but the decay resistance allow for long-lasting outdoor uses.
  Technology: Schlieren KUKA robot, Braun holtzwerk
  Reference: Long Bow, Reciprocal Frame Structures, Leonardo Bridge

 

Design subject

Although the module is open for design proposals, the module can offer a subject: a temporary bus stop of Verkehrsbetriebe Zürich VBZ, either at ETH Hönggerberg at Einsteinstrasse (Bus 80) or Nürenbergstrasse (Bus 33).

 

Schedule

27.05.13 14.00h Competition introduction: Introductory Lecture

28.05.13 10.00h Visit to Albisgüetli, purchase of test pieces (here)

03.06.13 10.00h  Design check point

10.06.13 13.00h Deadline design proposal, project selection (guest: Daniel Bosia)

24.06.13 Detailing and fabrication planning (guest: Christian Derix)

15.07.13 Assembly

 

Literature

Hageneder, Fred: Yew, a history. Stroud : Sutton 2007

 

Contact Person

Hironori Yoshida, yoshida@arch.ethz.ch

Mathias Bernhard, bernhard@arch.ethz.ch

External advisor

Christoph Schindler, christoph@schindlersalmeron.com, +41 (0) 79 257 67 90