Rollimarchini Architects and G8A Architects have designed a factory in Vietnam with three linear kilometers of stacked, green planters about its perimeter to naturally cool the building. The custom trellis system integrates products manufactured by the factory’s well-known parent company, Jakob, which include architectural tension cables and metal mesh.
Jakob Rope Systems is a Swiss manufacturer and supplier of wire ropes and rope nets that are respected in the architecture industry for their elegant engineering and high-quality detailing in stainless steel and inox. The family-run company was founded in 1904 and has created durable products used the world over in projects ranging from high-profile buildings, to bridge systems and animal enclosures.
While many of Jakob’s products are manufactured mechanically, some, including its popular metal mesh, must be handmade. For such a product to be viable on the international market, the company relies on production in Vietnam where workers are highly skilled yet labor costs lower than those in Europe.
When Jakob expanded its operations in 2015 to include a second Vietnamese factory in an industrial park near Ho Chi Minh City, it engaged Bern-based Rollimarchini Architects and Geneva-based G8A Architects to design a new facility that embodied the engineered precision of its own products. G8A, while headquartered in Switzerland, opened an office in Hanoi, Vietnam, in 2007, and has extensive experience designing projects suited to Southeast Asia’s tropical climate.
The 30,000 square meter site of the Jakob factory is located in an industrial park some 50 kilometers north of Vietnam’s economic capital, Ho Chi Minh City. It consists of a series of buildings housing work spaces and parking, arranged in the shape of a square to enclose a central courtyard much like the form of typical Vietnamese villages. The buildings make use of an intelligent, porous and generously planted facade which allows breezes to enter and cool its workspaces.
A new form of industrial factory
Vietnam’s recent rapid growth has resulted in the development of large industrial parks near to urban areas. Many factories have been built quickly and poorly, sprawling single-story constructions with large footprints that harm their local environments. To counter detrimental and polluting practices, Jakob’s management envisioned the construction of a green, environmentally-friendly facility.
“The CEO Peter Jakob sought to realize a building that was high quality and which could bring social value to its workers,” says Grégoire Du Pasquier, a partner and co-founder of G8A. “The brief was ambitious, and from the beginning he was looking for the most intelligent project for this factory, something that makes sense in the context.”
Rollimarchini and G8A conceived an open-air factory of stacked working zones to reduce its development area, making use of a massing that could offer workers access to outdoor landscaped spaces. According to the architects, the factory was the first in Vietnam with fully naturally ventilated manufacturing floors.
Responding to a tropical climate
Temperatures remain about 30 degrees Celsius year-round in Ho Chi Minh City. Any project built in southern Vietnam must contend with the region’s humidity and heat. Achieving thermal comfort for workers is vital in all building types, and passive design solutions can be hugely impactful for realizing comfortable spaces while also reducing electrical cooling needs. This is especially the case for factories, where operational hours are long and energy requirements are high.
“We started off by thinking about a work environment that is totally open and naturally ventilated, but at the same time protected from rain and sun,” says Du Pasquier. The architects developed a concept for a simple open-plan floor surrounded by a one-meter circulation space that would provide the needed depth for sun shading. The central manufacturing floor could be closed off from this perimeter space by sliding polycarbonate doors when needed, but would otherwise remain open on all sides for natural ventilation. The circulation space was wrapped by three linear kilometers of shallow stacked planters, filled with low-growth plant species native to the tropics.
Plants and passive cooling
Aside from giving the Jakob factory a soft and natural aesthetic, the planters filter rain and sun, and lower the atmospheric temperature by reducing the amount of direct sunlight hitting the building surfaces. The plants also act as air purifiers and dust particle binders to improve air quality for building users.
Plants are known to improve thermal comfort and are often applied to roofs, balconies, courtyards and facades with varying degrees of impact on a building’s microclimate. Plants can be used to control wind velocity and direction, as well as contribute towards cooling an area as water on their leaves evaporates into passing breezes. In the case of the Jakob factory, open facades on all sides allow the building to capture breezes from any direction.
Although cooling with the help of plants could lessen a building’s energy costs, it is worth noting that the cost of special maintenance – such as constant pruning, cleaning, soil replacement – could become more complex and expensive in urban locations. Due to maintenance requirements it is also considerably easier to integrate plants within the envelopes of low-rise buildings. In tropical climates, where rainwater supply is constant, green facades are often more viable as they rely less on pumping water from a city’s grid for plant care.
Detailing the planters
The planters are stacked the full height of the Jakob factory - up to three stories and some 12 meters in elevation. The vertical spacing of a little over one meter was dimensioned to allow for greenery to grow lushly while maintaining space for air flow into and across the deep factory floors.
The typical detail that was developed for the envelope includes both high- and low-tech material solutions to yield a sophisticated and visually light construction in which the planters seemingly float along the building edge, despite the considerable combined weight of the soil and planters. The system is structurally suspended using two layers of Jakob tensioned steel cables which extend from a concrete beam at the building foundation, to a pair of steel beams at the top of the facade. “The tension is quite high,” according to Andrea Archanco, an associate architect at G8A. “We had to work with the engineers in-house from Jakob to determine the values.”
The shallow and radial planter includes several layers of geotextiles, egg shell drainage, an antiroot layer and soil to support the plants and adequately distribute and collect water. A metal net also produced by Jakob is used to hold the buildup together. “We used Jakob’s own products to create a sort of showroom,” says Du Pasquier.
A mockup was produced for the project to test different materials for the planter including stainless steel and HDPE pipe made of high-density polyethylene. HDPE is a recycled, impermeable and flexible plastic often used for stormwater and drainage systems. It was ultimately chosen for its ability to bend to the shapes demanded by the project, while maintaining continuity. HDPE is also significantly lower in cost than stainless steel.
Consideration was given to each component’s ability to withstand constant humidity. The planter frame, cables and down pipes, as well as fixations, were all specified as stainless steel so as not to be corroded by water. “And when we specified the food for the plants, we had to request that it does not have a certain acidity to prevent corrosion,” says Archanco. “They have to be careful with chemicals.” Various drainage solutions and connections between planters were also tested. 160mm downpipes are spaced at 25 meters and used to drain the planters as well as the roof.
The entire planter buildup gives the building a textured, layered quality. Strong horizontal lines are expressed by the Jakob inox structure topped by thick greenery. This is overlaid with a crisscrossing series of thin tension cables which tie one floor to the next. Entrances into the building are marked by large thresholds which define the building’s scale.
Selecting plant species
The mockup produced by the architects was also used to test plant species onsite during a period of several months. “Some didn't work and some worked very well,” says Archanco. The plants selected for the project vary according to facade orientation. Species include tropical leafy and flowering plants such as rhapis excelsa, chamaedorea elegans, lemongrass, heliconia psittacorum, schefflera octophylla, ornamental trees such as yellow areca, Hawaiian areca, areca small trumpet and many more.
One of the main requirements for the plants was that they be able to bear the shallow planter depth. Plants were also selected according to height, with three categories for variation: low, medium and tall. “Due to ventilation needs the plants can’t grow too high, because space needs to be maintained between them for air flow into the factory,” says Archanco.
An automatic irrigation system with sensors is distributed about the facade to detect which plants are in need of watering, preventing dehydration and efficiently managing water use. Due to the building’s orientation, west-facing plants are irrigated more often. Water distribution also varies by planter elevation because shadows are cast on the building by surrounding structures.
Maintenance and long-term care
The plants are accessible directly from the factory floors, with rolling scaffolding required to maintain only the highest level of planters. Maintenance includes frequent pruning and weeding. “This is a tropical country and it is amazing how fast this greenery grows,” says Archanco. “Two people, full time, maintain the plants every day, cutting them section by section. They finish the three-kilometer length and then start again from the beginning.”
Landscape employees also check to ensure the plants are not waterlogged and that they water evenly. The average amount of water used is 5 liters of water per square meter per day. Cutting is periodic and maintained at regular intervals to help plants produce leaves while also limiting the growth of fungi and the breeding of mosquitoes and other pests. Every two years, it is recommended that a new layer of nutrient soil be added to the planters, refilling them to cover plant stumps and roots exposed due to erosion.
Lasting results
According to the architects the passive design strategies used in the Jakob factory help to reduce air conditioning use by 30 percent. Air conditioning is only used on the ground floor for a limited number of workday hours. “The temperature is really pleasant when you are there in the morning or afternoon,” says Archanco.
The project was completed in 2019 and, according to the architects, the facade system has not degraded. The design team is currently working on an extension for a second factory space adjacent to the existing project. Du Pasquier believes there are other interesting opportunities to make use of the facade in the future expansion. “One idea is to grow edible plants like lettuce for the factory canteen,” he says. “There is still more to experiment with here.”
