Facades are an essential aspect of architectural design. They envelope interior spaces and protect them from climatic conditions. Since facades are the first part of the building that people interact with, designers must consider aesthetics, maintenance and, of course, implementing sustainable materials. Below are some unconventional yet beautiful materials that can be used for facades to enhance the climate resilience and spatial qualities of buildings.

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“Yakisugi” timber facades

Across the globe, timber is a very common material used in construction. Depending on the geography of the region, various types of timber can be easily accessed and utilized for construction, especially for structural and cladding purposes. One traditional Japanese treatment for timber cladding is particularly unique. It is known as “shou sugi ban” or “yakisugi”, which can be translated as “burned cedar.” This charring process alters the chemical composition of timber to allow for increased durability and resistance to pests.

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The traditional “yakisugi” process features three boards of Japanese cedar that are bound to create a tall triangular form. A fire is lit at the bottom of the column and spreads upwards using the stack effect. It takes approximately five minutes to char 3-4 millimeters of the outer layer which is optimal for cladding, but this can vary depending on the moisture content of the slats. The result of the burning process is blackened wood with beautiful textures. To maximize “yakisugi’s” sustainable benefits, it is best if the wood is sustainably-sourced and/or reclaimed.

The heat treatment enhances the wood’s longevity by limiting rot and maximizing insect repellence and fire retardancy. “Yakisugi” cladding also does not need preventative maintenance. While “yakisugi” traditionally features Japanese cedar, the preservation techniques can be used for other species of timber found around the world. These various properties make the cladding a useful option for facades, as they are low-maintenance and long-lasting. The dark wood slats also evoke an elegant, monochromatic feeling on the building’s exterior.

A gabion wall on the water

Gabion walls

Gabion walls are common in landscape architecture because of their incredible structural properties as retaining walls. However, they are also gaining popularity as a form of masonry for building exteriors. Gabions consist of metal mesh cages filled with loose, locally-sourced materials like stones, sand and soil. Over time, gabion walls become even more structurally sound, as spaces between the stacked cages and gaps within the loose material fill with silt and vegetation.

Gabion walls are quick, easy and cheap to build because they use limited materials that can easily be sourced from the site. The materiality can also be selected to achieve various aesthetic qualities through deliberate choices of filler sizes, colors and textures. By controlling the porosity of the gabions, the walls can also provide natural cooling effects on interiors as air passes swiftly through narrow gaps. 

Because of their ease of construction and versatility, gabion walls are an interesting choice for building facades. They have several sustainable advantages, especially with regard to cost-effectiveness, which aligns with their sturdiness and intricately textured appearances.

Cork facade paneling

While the use of cork in architectural design is not new, cork panels are typically used for flooring or insulation. However, in recent years, granulated cork waste (from by-products of bottle cork production or recycled bottle corks) has been used to make facade panels.

Cork is made from the bark of cork oak trees, where the bark is gently peeled off the tree without damaging it. While the bark regrows, the trees absorb up to five times more carbon from the atmosphere than they would usually sequester, to help regenerate the bark. For every kilogram of raw cork produced, approximately 55 kilograms of carbon dioxide is sequestered from the atmosphere.

Meanwhile, the bark is a useful renewable resource that can be harvested to create bottle corks and facade panels. The raw material is lightweight, making it easy to transport and utilize. Cork trees also are low maintenance and do not require fertilizer, pesticides or pruning.

Cork paneling is a useful material for exterior facades. The raw material’s natural resins, which are released during the fusing process, allow cork products to be durable yet lightweight. These resins also allow for mold resistance without artificial additives. Because cork is hydrophobic, its products also take on water-resistant properties. These qualities make it a sustainable and versatile material for external surfaces while giving facades an attractive speckled look.

Green wall made with plants and a neon signs that says "and breathe"

Green walls

Incorporating plants into the built environment is a strategy that has been used for centuries. Green infrastructure, like roofs and facades, are practical yet beautiful solutions to regulate temperatures and enhance air quality.

Green facades are gaining popularity, but have historical roots. Over 2,500 years ago, the Babylonians pioneered vertical gardening through their hanging gardens. In the 17th century, countries like England and the Netherlands used fruit walls to regulate temperatures. Plants would grow up masonry walls, absorbing heat and creating a microclimate. 

There are three primary systems that green facades can employ. The first uses self-adhesive planting, which features plants that have tendrils, twining stems or suckers. These attach themselves to the wall and grow upwards from the ground. The second system uses climbing plants that grow vertically along the wall from the ground level and extend upwards. The final system is a cassette system that features plants that grow out of substrate pockets that cover a wall vertically. While this system requires more intensive care and maintenance, it also allows for more lush vegetation.

Green facades are excellent at regulating urban temperatures and purifying the air we breathe. The flora emits water vapor that cools the surroundings and increases humidity. It protects the interiors from direct solar radiation and acts as a form of insulation throughout the seasons. This allows for less reliance on active heating and cooling systems. Green walls are also useful for absorbing harmful substances like volatile organic compounds (VOCs), particulate matter, carbon dioxide and nitrogen from the air. These substances can cause health problems like respiratory diseases and other illnesses.

Using these facades

Sustainable buildings are more than concrete boxes with glass curtain walls that are plastered with solar panels on the roof. By utilizing some unconventional yet versatile materials for facade design, architects have the power to make our buildings sustainable and beautiful at the same time. Through meticulous material selection, facades can enhance well-being of living organisms, maximize cost-effectiveness of construction and boost climate resilience in urban spaces.

via Japanese Woodcraft Association, Zhuoda Metals, Yuzu Magazine and Urban Green-Blue Grids

Lead image via Wikimedia Commons (License), body images via Unsplash