Green densification model

A greening project in Laval aimed to replace impermeable surfaces such as asphalt with vegetation. This process would allow water to infiltrate the soil on a surface area of 3000 square meters and plant 7200 plants on land located near or inside urban heat island zones of the city (Ref. 1,2,3,7). The project takes an integrated approach to mitigate the impact of urban heat islands, which make up 12-13% of the territory in Laval (Ref. 1,7). Particular focus of this project is placed on planting on sites of vulnerable communities (Ref. 1,3).

Since 2008, the City of Portland, Oregon has used various policies and programming to encourage the use of eco-roofs (vegetated roofs) throughout the city to address stormwater management (Ref. 2,3,4). In addition to stormwater management, eco-roofs have the benefits of: saving energy, reducing pollution and erosion in waterways, preserving fish habitats, creating new habitats for birds and insects, absorbing carbon dioxide, cooling urban heat islands, filtering air pollutants, and providing urban green space (Ref. 1,5). From 2008 to 2012, the City of Portland used the Ecoroof Incentive program to encourage property owners and developers to construct ecoroofs (Ref. 4,5,12). In 2018, the City of Portland adopted a mandate for ecoroofs in new buildings (Ref. 2,3,12). These policies and programs led to a growing interest in the use of ecoroofs, and resulted in the construction of over 130 ecoroofs (Ref. 3,4,11).

The green belt was created not only as an aesthetic element but also to serve as the lungs of the city. The forest planting works around Nur-Sultan have been carried out since 1997 [6, 7]. The area of ​​the green belt of Nur-Sultan is 100 thousand hectares, of which 15 thousand hectares are planted within the city limits. The main idea of the project was to provide comfortable conditions for the residents of Nur-Sultan city, which would serve as a mechanism for improving air quality, mitigating climate and as a natural barrier to protect the city from dust winds and snowstorms [2, 4, 5, 6, 7]. An important aspect that was taken into consideration are the animal species of the forest, as the territory of the green belt is inhabited by foxes, hares, corsacs, white and grey partridges, roe deer, wild boars, etc [1, 2, 7, 8]. The primary importance of biodiversity efforts is assigned to the breeding of birds, especially pheasants [1, 2, 3, 4, 5], as pheasants are an element of local cultural heritage, and on the territory of the green belt, traditions and cultural events related with the pheasants are organised every year [2, 4]. The young forest should turn into an improved recreation area, a favourite pastime for city residents at any time of the year [2,7].

The Sino-Singapore Tianjin Eco-City (SSTEC) is a bilateral project between Singapore and China with a large scale private-sector involvement with the objective to "transform the 34 km2 barren, non-arable land and polluted wastewater ponds into ... a thriving city which is socially harmonious, environmentally-friendly and resource-efficient – a model for sustainable development for 350 000 residents. (1,2). The Eco-Valley is an S-shaped, 11 km green spine that runs through the whole Eco-City connecting its centre with sub-centres, all four residential districts, community spaces, multiple parks, commercial zones, and waterside areas as a scenic park providing a place for connectivity, transit, leisure and recreation for residents (1).

The Cheonggyecheon Stream Restoration Project saw the dismantling and removal of an elevated freeway and the uncovering of a 5.84km section of the Cheonggyecheon historic stream in the centre of Seoul, South Korea (Ref. 2). One of the world’s largest and most densely populated cities, the revitalisation of the Cheonggyecheon Stream has provided Seoul with an ecologically sensitive green pedestrian corridor in an area that was previously recognised as being congested, overpopulated and polluted (Ref. 4). The restoration has provided environmental, social and economic benefits within its immediate proximity (Ref. 2). In addition to becoming a "vehicle for revitalisation, urban renewal and economic development", it has "also signified a shift in Korean planning priorities", with both city authorities and residents now placing an emphasis "on health, sustainability and social responsibility" (Ref. 4). It has further "become a template for planning intention and action across South Korea" (Ref. 4).

The 'Step Garden' is a 14-tier green roof atop the Asian Cross Roads Over the Sea (ACROS) Fukuoka Prefectural International Hall in Fukuoka, Japan (Ref. 2). The Hall itself is a centre of international, cultural and information exchange, and sits amidst the Tenjin Central Park (Ref. 3). As the building displaced a plaza, the architect, Emilio Ambasz, created the “image of a mountain" through the design and installation of the roof terrace (Ref. 2), "want[ing] to give back to Fukuoka’s citizens all the land the building would subtract from the city" (Ref. 3). In combination with the Central Park, the rooftop garden is considered to be the only open green space in the city centre (Ref. 4), and since its inauguration in 1995, has been open to the public, accessible via two entrances on the park side of the building (Ref. 1).

Having been awarded the LEED Gold certification, the President Place building is considered the greenest building in the city. The building has been designed to create an exceptional balance between work, life and the environment. The 9th and 13th levels of the building have green roofs and terraces. President Place selected climate-tolerant plants that can survive on natural rainfall, and thus the green roof system does not require a permanent irrigation system. Effective practices were considered during the installation of the green roof, such as mulch for trees to conserve moisture, choosing plant species that can easily adapt to the site and need less irrigation. Trees have also been planted on the ground level. Additionally, the building is surrounded by permeable paving to help rainwater percolate easily. The aim was to create a visually appealing office building that leads the way in environmental, design-led construction in Saigon. [1, 2]

The Million Trees project was a programme launched by Auckland Mayor Phil Goff in 2017 to plant a million predominantly native trees and shrubs over a period of three years (Ref. 1,2,3,4). It aimed to make Auckland a greener, more beautiful place while creating carbon sinks, protecting the city’s waterways and improving the city’s living environment (Ref. 2,4). The programme engaged a variety of actors in the planting activities, including local boards, iwi, schools, service and social sector groups, private entities, the council group, the New Zealand Transport Association (Ref. 1). Particularly notable partnerships included those with the Department of Corrections and the Trees that Count Trust (Ref. 2,4,6).
The initial goal was met in 2019, and the project has been renewed for 2019-2022 (Ref. 1,7).

The green roof pilot project is part of eThekwini Municipality's Climate Protection Programme, initiated in 2004, it was focused initially on understanding the vulnerability of the city of Durban to the impacts of climate change. A strong emphasis has been placed on identifying climate change adaption projects that will improve the resilience of the city to future developmental, social and environmental challenges. Basically, the green roof pilot project is a response to the higher temperatures and increase in the frequency and severity of floods and droughts that are expected as a result of climate change. From an urban environment perspective, these changes will exacerbate the already high temperatures experienced as a result of the Urban Heat Island effect and the high levels of surface run-off and flooding that result from the hardening of permeable surfaces. (1,3)

In 2015 an innovative project called the "Sweet City" (Ciudad Dulce) was launched in Curridabat. Its main goal was to bring wild spaces into 21 urban neighbourhoods of Curridabat ("spaces of sweetness") and eight corridors ("transitions") and thus linking neighbourhoods and parks through a participatory re-design approach with local stakeholders [3]. The main objective of the Sweet City model is to reintroduce biodiversity into the urban space by focusing on five fundamental dimensions: Biodiversity, Infrastructure, Habitat, Co-existence and Productivity. The interventions of this project included park improvements, sustainable drainage systems, the protection of wetlands, spring water recovery, promoting organic farming practices, and many strategies that help improve biodiversity and motivate citizen participation, finally, as ecosystem-based disaster risk reduction measures and climate change adaptation actions [1].