In Taiwan’s dense cities, concrete is giving way to green as buildings and public spaces embrace plants to beat the heat.

STORY AND PHOTOS BY LILLYGOL SEDAGHAT AND CORY HOWELL HAMADA

Framed by lush foliage, the Kaohsiung Main Public Library stands as a showcase of energy-saving innovations. The eight-story building, adorned with more than 700 trees in and around its perimeter, is topped with an accessible green roof and anchored by eight mature Asian bayberry trees that ascend through a central glass atrium.

The library is part of a growing wave of “urban greening” architecture, a concept that incorporates plants, shrubs, and trees into building designs. This trend offers a range of benefits, from cleaner air and enhanced support for urban biodiversity to reduced energy consumption through natural temperature regulation.    

“There’s been a great deal of consideration around energy savings in the entirety of the design from the inside function to the use of outdoor space,” says Kaohsiung Public Library Director Lee Chin-yang. By optimizing natural ventilation, sunlight, and insulation, the building conserves energy while providing a pleasant experience for visitors. “We want people to feel like they are in a comfortable environment,” she says.

According to the World Meteorological Organization, 2024 was the hottest year on record. Urban areas bore the brunt of the heat, with temperatures amplified by the urban heat island effect, a phenomenon in which cities absorb more heat than surrounding rural regions and release it more slowly, elevating temperatures. Additionally, a 2024 report by the Columbia Climate School at Columbia University found that air conditioning alone contributed 7% annually to global greenhouse gas emissions, nearly 80% of which came from the energy used to power cooling systems.

In Taiwan, where average summer temperatures hover around 29°C, cooling systems are among the largest consumers of energy. According to the international journal Sustainable Cities and Society, air conditioners account for the greatest share of electricity use in Taiwan’s residential sector. The study also found that between 30% and 50% of household electricity consumption during the summer is tied to climate change. Notably, electricity usage from cooling systems increases by 5% for every 1°C rise in temperature during the summer months.

As global air conditioning emissions are projected to double by 2030 and triple by 2050, the United Nations and European Commission have identified urban greening as “one of the most essential nature-based solutions for mitigating and adapting to urban warming.”

Designing buildings as trees

Completed in 2014, the Kaohsiung Main Public Library is the world’s first column-suspended green building – an achievement that is as much an architectural innovation as it is an environmental one. Massive columns elevate the structure above ground level, minimizing its footprint and creating space below for breezeways, green courtyards, and gardens.

Aesthetically, the shaded open spaces and soaring columns evoke the feeling of a tree canopy. During early planning stages, the city government conducted a survey asking residents what they envisioned for the new library. Many said they wanted a space that felt like reading beneath a tree.

“Our design concept is trees inside the library, and the library inside trees,” says Lee. This vision guided the creation of a place where nature and community, both deeply meaningful to people in Taiwan, quietly overlap. “We think of ourselves as a cultural living room for all the citizens of Taiwan,” she says.

One of the library’s most visible features is its western façade, where rows of trees are planted directly into the third to eighth-floor balconies, forming a multi-level green wall. The library estimates that the surface temperature of the glass behind the trees is 3°C lower than the outside air, saving over 1,400 kWh of electricity in daily air conditioning use.

“When you compare a building with plants and without, a building with plants can reduce surface temperature on the building by 15°C to 30°C, reduce outside temperatures between 2°C and 4°C, and decrease inside temperatures by between 2°C and 3°C,” says Fang Chih-fang,  associate professor of landscape architecture at National Chin-Yi University of Technology (NCUT). She adds that the use of green walls like the library’s western side and green roofs can reduce a building’s total energy use by 6%.

More leaves, less heat

Recent residential developments, such as Taipei’s Tao Zhu Yin Yuan – also known as Agora Garden, completed in 2018 – have similarly embraced greening strategies to enhance energy efficiency and promote a more livable urban environment.

Built to model a double helix, the Xinyi District high-rise is “energy self-sufficient,” meaning the complex generates as much energy as it uses. Its vertical gardens – comprising 23,000 plants along with a variety of trees and shrubs – envelop the building’s entrance and are found on each of its 21 spiraling floors. The design has been shown to lower ambient temperatures by around 4°C in the summer and cut air conditioning use by roughly 30%.

According to a statement co-authored by architect Cheng Hsiu-Lin and Design Director Yang Chia-Wen from SED-IA Architects, a firm focusing on architectural design services and the local architecture partner for Agora Garden, the idea was conceived in 2009 from a desire to reduce emissions in the built environment. “At that time, energy conservation and carbon reduction had become an international trend, and carbon emissions from the construction industry accounted for about 40% of global emissions,” note SED-IA architects in response to questions for this article.

As part of the building’s cooling strategy, plants and shrubs with high leaf density were chosen for their elevated leaf area index – a measure of leaf coverage relative to ground area – which enhances the shading effect and contributes to greater temperature reduction.

Tree coverage above or surrounding buildings is particularly notable for its potential cooling. A 2021 study in the Journal of Sustainable Development of Energy, Water and Environmental Systems – also cited in Nature, one of the world’s most prominent peer-reviewed journals – found that trees could provide “a 1.8-4°C cooling effect on roofs and up to 15°C for indoor temperature reduction,” creating a significant decrease in energy needs during summer months.

Aside from the impact on individual buildings, the benefits of utilizing vegetation to regulate urban temperatures and reduce energy consumption are increasingly being acknowledged. Singapore’s Green Plan 2030, for instance, aims to plant one million more trees and add 1,000 hectares of green space to counteract the rise in urban heat. Likewise,  Australia’s Greening Sydney Strategy sets a goal of achieving 27% tree canopy coverage in the city by 2050 – an effort that could lower ground temperatures by as much as 10°C.

“The more leaves, the better the energy savings,” says NCUT’s Fang.

In Japan, the ACROS Fukuoka multi-purpose commercial complex exemplifies integrating greenery for both aesthetic and environmental purposes. With a height of 60 meters, the stepped “urban mountain” was originally seeded with 37,000 trees from 76 species. In addition to offering panoramic views of Fukuoka City and Hakata Bay, the building has helped reduce surrounding temperatures, according to a study by Kyushu University.

While research suggests that the temperature-regulating efficacy of green coverage is similar internationally, Fang says that one of the major challenges to urban greening is choosing “the right plant for the right place.”

“Singapore has a lot of green walls, but we realized that if we used Singapore’s style of building green walls, it wouldn’t work in Taiwan,” says Fang. “Taiwan has typhoons and earthquakes, and the west and south sides of the island experience drought for much of the year. So if you want to build green walls, your structure and planning must be sound.”

Even within Taiwan, urban greening efforts are tailored to local environmental conditions. At the Kaohsiung Main Public Library, proximity to the ocean requires the use of plant species that can withstand salt air. In Taipei, the vertical greenery of Agora Garden must be adapted to the city’s climate and engineered to endure strong winds at higher elevations.

Fang points to the cost and maintenance of greening projects as another major hurdle to implementation. Vertical greening is expensive, often requiring complex irrigation systems and ongoing maintenance. Replacing dead plants, for instance, can be particularly labor-intensive. But according to Fang, selecting appropriate vegetation, such as low-maintenance vines or climbing plants for walls, can help mitigate these challenges and improve long-term sustainability.

“Vertical greening in high-rise buildings requires regular maintenance and management such as pruning, fertilization, and pest control,” reads the statement from SED-IA Architects. “If the right plants aren’t chosen, the original goals of energy saving cannot be achieved.”

Cultural considerations also play a role in promoting the widespread application and general acceptance of urban greening in Taiwan. In Eastern cultures, the principles of feng shui – centered on creating harmony and balance within a space – play a significant role in plant selection for both indoor and outdoor environments. Certain species are chosen to enhance positive energy, while others are avoided for their perceived negative influence. The banyan tree, for example, is rarely used in urban greening designs because it is believed to attract “yin energy,” which is associated with spirits and thought to disrupt the harmony of a home.

Modern approaches to wall greening can sometimes run up against traditional beliefs. In the past, vegetation growing on wooden houses was thought to compromise structural integrity, promoting wood rot, trapping moisture, and potentially causing illness. These associations continue to influence perceptions, despite advancements in building materials and moisture management systems.

Still, public attitudes toward urban greening – particularly vertical greening – have become increasingly favorable. A 2014 survey shared by SED-IA Architects found that 85.4% of respondents supported the promotion of vertical greening in cities, while 75.2% expressed a willingness to implement it in their own homes.

On a policy level, Taiwan supports urban greening from the perspective of increasing air quality, promoting biodiversity, absorbing carbon emissions, and improving urban livability. Meanwhile, local governments have increasingly embraced urban greening as part of broader energy-saving strategies.

Programs such as Kaohsiung’s “House Design and Rewards Program” and Tai-chung’s “Feedback Measure for Encouraging the Installation of Livable Building Facilities” offer clear guidelines and incentives to encourage the adoption of green façades. Similarly, Taipei’s city-wide cooling plan leverages urban greening to enhance building energy efficiency and reduce carbon emissions.

As cities around the world embrace urban greening, the human benefits of access to green space are also significant. Numerous studies point to improved physical and mental health, lower stress levels, and greater social cohesion when people live near greenery. Taiwan’s adaptation and acceptance of this architectural trend across its cities can help support and solve many of its urban issues – all that’s needed is a little less gray and a little more green.