AECOM Roof Garden: From Corporate Garden to Nature Space Advocacy, Part 3

by Lee Parks, International ASLA, and LIAO Jingjing

Teamwork to revitalize the roof garden / image: courtesy of Chen Liang

This is the final installment in a three-part series on the evolution of AECOM’s green roof in Shanghai. Click here for Part 1 and Part 2.

2021 Revitalization, Stage 2

In 2021 the roof garden vision was updated to: “increase amenities, encourage outdoor garden use by employees, increase contact with nature and fresh air.” In line with corporate environmental, social and, and governance (ESG) strategies, the roof garden offered a real opportunity for employees to protect the environment, socially interact, to have equitable access to nature, and to govern the garden for the benefit of people, place, and nature. The increasing biodiversity also demonstrated the roof’s potential as an ecological stepping-stone for a greener community.

Improving the garden included plans for a range of quiet, semi-private spaces and open multi-functional spaces to create more attractive and engaging places for employees. This included new vibrant colored moveable tables and chairs to activate lunchtime use. Additional plant containers were added to increase nectariferous species for greater ecological and social benefits for employees, our community, and for wildlife.

The 2021 improvements focused on people, place, and nature, increasing amenity and ecological aspects of the roof garden. / image: courtesy of Lee Parks, AECOM
A custom-made workspace table was proposed in the 2021 revitalization plan. / image: courtesy of Lee Parks, AECOM
A ping-pong table was also proposed in the 2021 revitalization plan. / image: courtesy of Lee Parks, AECOM

With limited budget, the priorities balanced on environmental and social improvements and once again drew attention to the roof garden with a revitalized Roof Garden Committee and refreshed social media group. Many employees took part in building containers, planting out new species, and adding labels to plants in Latin and Chinese for identification. What was once proposed as a high-end barbeque area had now become more akin to an allotment garden shed, housing garden tools and accessories. To the end of the garden a composting facility was added to manage garden waste and provide habitat for a wider range of beneficial insects, such as beetles, to assist in breaking down organic matter to form garden soil. Bamboo, planted in 2015, had now established well and each spring, new shoots emerging could be harvested for bamboo canes to support taller perennials.

Explaining planting techniques / image: courtesy of Lee Parks, AECOM
Writing plant identification labels / image: courtesy of Lee Parks, AECOM
Teamwork to revitalize the roof garden / image: courtesy of Lee Parks, AECOM
Labelled plants / image: courtesy of Lee Parks, AECOM
Labelled plants / image: courtesy of Lee Parks, AECOM
New parasols and moveable tables and chairs in vibrant yellow color / image: courtesy of Lee Parks, AECOM

The increases in plant diversity included a mix of native and non-native plants to test ecological fit to Shanghai’s climate. Like the previous revitalization efforts in 2018, the 2021 initiative experienced a cycle of employee interest followed by declining interest in summer. Shanghai’s unforgiving heat and humidity was only eased by the provision of shade from new parasols. The moveable tables and chairs became more frequently used, with some employees moving chairs to specific locations in shade for solitude, quiet lunches, or as a place to relax and chat with colleagues. In conjunction with the 2021 improvements, AECOM participated in a Community Garden Festival, opening the roof garden to visitors including Tongji University Professor Liu Yuelai (a key advocate for community empowerment, social equity, and community gardens) as well as guests and media.

Visit by Professor Liu Yuelai, guests, and media as part of a Community Garden Festival / image: courtesy of Lee Parks, AECOM

During 2021 and the early part of 2022 other higher species of wildlife were spotted on the roof garden including geckos and birds, a further testament to the growing biodiversity and establishment of an ecosystem. As more leaf litter and plant waste decomposes and creates humus in soil, aided by fungi and insects, this attracts predators to feed on insects.

2021 improvements increased plant diversity, including Iris domestica. / image: courtesy of Lee Parks, AECOM
2021 improvements encourage employee activities, including a movie night to watch Five Seasons by Piet Oudolf. / image: courtesy of Lee Parks, AECOM
A visiting film crew to discuss the role of roof greening for city resilience / image: courtesy of Lee Parks, AECOM

The Pandemic Return

In the spring of 2022, the pandemic return led to a period of office closure for over two months. After several years of limited maintenance, the two-month gap was a good test for resiliency and the ability of plants to thrive with zero maintenance. The diversity of the plantings after the lockdown and vigor of some species was a positive surprise. In 2022 we also experienced one of the longest heat waves and drought, a clear indication of a changing climate.

The 2022 office closure during an extended outbreak of the pandemic led to a two-month period of zero maintenance. Surprisingly many of the plants were resilient and thrived with more wildlife enjoying the garden without people. Seeds of Gaillardia grandiflora complement the yellow tables and chairs. / image: courtesy of Lee Parks, AECOM
Unrestrained bamboo growth / image: courtesy of Lee Parks, AECOM
Eryngium / image: courtesy of Lee Parks, AECOM
The central lawn turns to tall meadow / image: courtesy of Lee Parks, AECOM
New compost bins / image: courtesy of Lee Parks, AECOM
Predatory ladybugs / image: courtesy of Lee Parks, AECOM

Transition of the roof garden from 2015, 2018, and 2021, with increasing green coverage to mitigate urban heat island effect and minimize stormwater run-off through the addition of planting containers:

image: courtesy of Lee Parks, AECOM
image: courtesy of Lee Parks, AECOM
image: courtesy of Lee Parks, AECOM

Lessons Learned

The 2015 aspirations of a hospitality-style terrace for corporate and VIP events did not align with the needs of the majority of daily users (the employees). Subsequent adjustments increased employee engagement, but the reality of Shanghai summers, the impact of the pandemic, and extreme weather events such as heatwaves, drought, and flash flooding deter longer employee engagement and use of the roof garden. Low maintenance, resilient ecological approaches have a more practical approach to roof gardens in corporate settings, which the 2022 lockdown proved. The evolution of the roof garden was brought about by unpredictable change, user behavior, and the challenge of attracting volunteers to champion the garden committee and maintenance.

Even with positive support from senior management to deliver environmental, social, and governance (ESG) strategies, sustaining a roof garden requires a high degree of passionate individuals to promote social interaction and appropriate governance of the roof garden. Without passionate and dedicated individuals to drive initiatives and keep the momentum going for roof garden committees, it is likely that Shanghai’s harsh summer and cold winters deter most users to engage in roof garden activities.
Without a high commitment to maintenance and investment to replace, repair, and upkeep facilities, the longevity of furniture or timber elements deteriorates quickly in exposed outdoor conditions. Plants that are not adapted to drought tend to disappear in summer under heat stress and summer typhoons. Extreme rain events can saturate planting areas if too much hard surfacing is used, reducing the effectiveness of roof gardens to mitigate urban heat island effect and minimize stormwater run-off.

After some seven years of establishment and revitalization, approximately every two to three years the AECOM roof garden appears to be returning to a pre-designed state where a variety of drought tolerant hardy plants are the optimum approach to tackle the interconnected crisis of climate change and biodiversity loss, and acknowledges that employee use of outdoor space is predominantly in the limited window of spring and autumn seasons. A wide range of native and non-native plants with suitable ecological fit to the harsh environmental conditions are essential to attract pollinators and a wider range of other species.


For those considering a roof garden as part of an office or campus environment in Shanghai or in a similar climate, it is strongly advised to consider the whole project lifecycle from design to management and long-term maintenance. There needs to be a budget for repairing and replacing non-durable items and dedicated maintenance of plants during the harsh summers and cooler winters when employees or volunteers are fewer in number. If there is no long-term commitment or budget, then opting for an ecological and low-intervention approach to roof greening is advisable. This supports nature and climate change mitigation rather than only focusing on people’s needs.

Lee Parks, International ASLA, is a British landscape architect and Executive Director at AECOM, based in Shanghai. His research focuses on ecological landscape planning, green infrastructure, Nature-based Solutions, and ecological planting design.

LIAO Jingjing, Master, is a landscape designer at AECOM. Her research focuses on green infrastructure, Nature-based Solutions, and community renewal and empowerment.

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