*4.2. Statistical Analysis of Six Communities and Nanhuan Community*

The 6 communities analyzed in detail have a floor area ratio that ranges from 0.95 to 1.75, on average 1.27, while the average FAR of all 176 cases is 1.73, the minimum is 0.7, and the maximum is 3.87 (Table 5).

For example, the Nanhuan New Village in Suzhou is a noteworthy case of densification. It is a demolition and reconstruction project in Suzhou, which was completed in 2013. Unlike the original community, the new community uses high-rise building types and different green space layouts, increasing the FAR value from 1.1 to 3.87 and tripling the total number of units. This attempt has shown that renewal is also a viable option when reassessing and transforming demolished and rebuilt communities, which can promote sustainable urban development while providing more housing.

The highest FAR is in Nanhuan New Village, Gusu District, which is the only case in Suzhou of the renewal with densification of a resettlement community, Nanhuan Community, initially built in 1996 on agricultural land. In 2013, the former community was partially demolished and rebuilt with a different housing type, high-rise buildings, a different layout of open space and green areas, and a FAR more than 3 times the former one, which was 1.1.


**Table 5.** Comparison of the main characteristics of the traditional resettlement village in Suzhou with Nanhuan New Village.

#### **5. Discussion: A Strategy for Renewal and Densification**

If the resettlement villages are chosen as targets for renewal and densification because of their architectural and urban characteristics, which ones should be selected and why? This paper proposes three options and evaluates their possible significance.

Based on the GIS analysis, some rationalities for selecting which communities to densify can be proposed, together with a process of gradual transformation in the medium term according to the existing policies. The project of densification should be site-specific and take into account multiple factors; that is to say, each specific renewal can define how to optimize the FAR in the re-design of the site, but some general conditions where densification should happen can be identified.

The paper considers the residential neighbourhood's main quantitative factors number of units and residents, dimensions of the area, public transportation, and period of realization—for a quantitative investigation of the possibilities of transformation with densification with the goal of using more intensively the land already urbanized. Before real actions are promoted, every proposal of densification will assess if the land is suitable for densification due to soil and seismic conditions, the land carrying capacity, and the land subsidence risks. The potential impact of natural disaster on the increased concentration of residents will also be explored to assess the possibility of safety in an emergency. During the decision-making phase, feasible mitigation and compensation measures will be studied to balance the impact on the environment of the demolition and building activities [4,5,7,17,19,20,69–72].

#### *5.1. Densification according to FAR and Accessibility*

The first option is the selection of cases to renew according to the intensity of land use expressed as FAR. Renewal and densification should be proposed in the resettlement communities which:


• Next to metro stations or transport interchanges (within 400 m from one of the community gates) and have a FAR lower or equal to 2 to fully exploit the transport capacity and accessibility of the site. Specific projects should define the most proper threshold of FAR according to the local conditions and the transport capacity.

The analysis of the available GIS data of the built fabric and the public transit infrastructures allows us to determine which resettlement communities are both low-density and within a radius of 400 m from a subway gate or a bus interchange, or a terminal (Figure 4c).

These first groups of communities can be pilot projects to test potentialities and obstacles to realize the optimum potential of sites. To what extent the FAR can be increased must be assessed in the local context, and multiple factors must be considered, including social infrastructures.

Other indicators can be considered to propose a community renewal, such as the quantity and quality of the open and recreational space. The communities with a building coverage higher than 25% and a green coverage of less than 30%, which means the open area of the community is mostly for mobility, should be investigated to assess the quality of the open space they offer combined with the FAR.

If this renewal happens, the value of the redeveloped estate will exceed the original value of the estate plus the cost of change, which is the expense, the temporary problems for the inhabitants, and the impact on the environment for the demolition and rebuilding. The upheaval of people's lives and improvement of living conditions should be included in the viability assessments, and some form of subsidy should be provided. These concerns are partially reflected in China's national compensation policy, which considers the residents' needs while dislocated; its main elements are:


In general, the evaluation of increased density should be in relation to the perception of the urban environment from the inhabitants, and high density must avoid extreme living conditions [24] (Figure 4b). Local public participation processes should be organized to involve the inhabitants in the decision making processes, but this is still rather rare in China.

### *5.2. Densification according to Housing Conditions*

Considering the relevant investment needed, the social trade off, and the fact that new constructions are resource intensive and have high environmental impacts, the second option evaluates a non-destructive solution and the upgrading and retrofitting of the existing structures [96]: actions of densification that maintain the existing structures can be designed. The examples of Seoul and Rotterdam show it is possible to infill, build over, and build in-between existing buildings, even though these actions usually cannot substantially increase the number of people in the communities. They invest a few resources, do not demolish the houses of those who have already experienced one resettlement, and reduce the impact of reconstruction on the environment [97].

Specific projects must define these punctual actions of densification and their contribution to the whole city housing offer cannot be esteemed without a general plan that sets goals and targets. These kinds of actions indicate that to grow denser might be to build a compact city, not a super-density city [98,99], and might be to realize different housing types than the ones usually built in Suzhou, such as the compact superblock. A research-by-design or a design competition for new housing types in Suzhou should be promoted (Figure 4c).
