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Archive for February, 2010
Tree Walls and Towers
Feb 27th
Research Group Baubotanik at the Institute of Theory of Modern Architecture and Design in Germany has been heavily researching the use of plants in construction. The idea is not new, but it still needs more testing before becoming a viable eco-friendly construction alternative. They just put up a Baubotanical green tower made of living trees. This prototype structure is located in southern Germany and is going to act as a way to test the construction method’s practicality.
Green Wall Tower
Baubotanical research covers designing load bearing architectural construction using living plants that slowly evolve over time into strong, fully grown trees. This is different from installing living fences or green screens or curtains in that the trees will support heavy structures. The tower above was made of hundreds of young 6 foot tall plants. The plants at the bottom of the tower are in the soil while the rest are planted in containers going up the structure. The containers are resting on temporary steel scaffolding which will be removed once the trees are strong enough to support the platforms themselves. The purpose of the multiple plantings is to speed up the growing process. Just using the trees on the ground might take several decades for them to be tall and strong enough to perform the purpose, but by growing them on multiple layers, the trees can be grafted into each other to grow to be one organism. Using this technique, the growth time is shortened to between 8-10 years. via Science Daily.
That idea would help further a project thought up by the Massachusetts Institute of Technology
Team H.E.D. [Human Ecology Design] including Mitchell Joachim, Ph.D., Lara Greden, Ph.D. and Javier Arbona, M.S.: Fab Tree Hab.
Fab Tree Hab
The Fab Tree Hab is designed to be grown out of native trees and grafted into shape by reusable scaffolding. The trees would involve arboreal farming and production and keep accountable of the life cycle of the dwelling as a whole. You can see from the image the large trees would be the main frame and support for the house, but even the walls would be made up primarily of living trees.
Fab Tree Hab
That thick green weave you see in the picture would be created from pleaching the trees together. Pleaching is an older technique of encouraging trees to grow into each other by weaving tree branches to create lattices or green screens. Elm, Live Oak and Dogwood would be used as the main load bearing trees and their branches would be weaved together to help form the lattice. It would be helped by vines as well as plants grown in pockets of soil throughout the wall. The overall process would create a dense foliage for the walls.
Fab Tree Hab
Water would be the heart of the structure. It would be collected in a basin in the roof, used by humans and would leave by transpiration. The water would have two streams: one would water the garden and the other would be filtered by a living filter consisting of beneficial bacteria, fish (like in aquaponics) and plants (the roots of the plants help clean the water). The water used by the housing vegetation eventually evaporates which cools the home.
Biowalls Explored in More Detail
Feb 25th
Biowall
A 24-square meter plant wall – more specifically a “biowall” – was built in the Robertson Building. The biowall was planted with a variety of exotic and native indoor flowering plants. Each plant has its own pocket in a special planting material (they don’t tell you the exact fabric they use). Water filters through the material to the plants’ roots and fresh air is continually pumped into the room via the living biowall.
The biowall purifies and cleans the air. The plants were chosen for their ability to tolerate indoor lighting conditions and their ability to improve indoor air quality. Some of the common contaminants come from traffic outdoors as well as off-gassing from furniture, paints, drywall, photocopiers, and human fragrances in the building.
The biowall helps filter Volatile Organic Compounds or VOC’s. VOC’s are actually a group of pollutants indoors and out. While small concentrations of these chemicals aren’t dangerous, over time they can contribute to “sick building syndrome,” which can include eye, nose, and throat irritation, headaches, and dizziness.
The biowall only needs typical plant maintenance including occasional dusting and removal of wilting foliage. Two 1000 watt lights provide supplemental lighting.
Living Biowall
A separate biowall was installed in the IL Centre. It’s 3 stories high and is aesthetically pleasing as well as acting as a biofilter which removes the VOCs and CO2 from the air.
Plants are easily swapped if they don’t thrive. The plants that work on the wall will vary depending on its requirements. Leafy ferns do better than Hibiscus, and orchids have done very well. Here’s a rundown of the plants used in the biowall:
- Aglaonema (Algaomema commutatum) & Spathiphyllum spp. (mixed aroids)
- Spider plant (Chlorophytum)
- Croton (Codiaeum)
- Cordyline
- Dragon Plant (Dracaena)
- Ficus (verigated)
- Rubber Plant (Ficus Elastica)
- Ivy (Hedera)
- Palms (Dypsis, Howea, or Chamaedorea spp.)
- Maidenhair Fern (Adiantum)
- Philodendron (several species)
- Snake plant (Sansevieria)
- Purple Heart (Setcreasea pallida, similar to the common Tradescantia)
- Umbrella Plant (Schlefera)
Diagram of basic biowall setup
Two layers of a porous material make up the fabric attached to the concrete wall. It’s 1 inch thick and is made of loosely woven plastic screwed to the wall in pieces. The top layer has slits cut into it where the plants are placed. The roots hold the plants in place and grow between the layers. The plants chosen don’t spread pollen and the constantly running water and fresh air prevent mold. A vapour barrier was installed in front of the concrete and behind the drywall to prevent moisture from spreading. What makes this vertical garden into a biowall are the fans that draw the air from each of the three floors to circulate through the building. You can see an informative flash image at queensu.
