Under the pressure of rapid urbanization, the development of urban land in Vietnam has invaded green lands and had a negative impact on their ecosystems and environments. The new urban development not only does not improve the demand for green urban space but makes the living environment worse. Studying the design seriously and putting forward solutions for green urban space is essential and urgent. Taking Da Nang as a case study, planning a network of multicenter urban green space would change ecological principles to create a sustainable urban ecosystem. This is based on a landscape metrics method to reveal the green space system characteristics and its spatial distribution, area, density, and shape. A set of shapes index including categories such as SHAPE, mean distance (m) between each cell (GYRATE) and mean Euclidean distance neighbour (ENN) was used to display the geometrical shape of patches and continuity. These indices stress the difference in spatial structure in various land-use types. This article draws upon ecological landscape theory to propose a green system of urban regions including green space wedges, greenways, corridors, greenbelts and green additions; these factors help to create a sustainable urban green space.

Residents have territorial cognition with different hierarchies and conduct corresponding behaviors in the outdoor space of housing blocks through sharing space and facilities. This mechanism stems from human need and might be influenced by physical environmental elements. To understand this effect, especially after a guideline for transforming existing gated housing blocks was enacted in China, this study compared the territoriality of open and gated housing blocks from the view of the cognition, behavior, and space through combined methods. Interview, snapshot, and observation were conducted to capture the situation of these three dimensions, then they were evaluated and grouped by factor analysis and quartiles. Obtained results in the open housing block were found to be inferior to that in the gated case. The conclusion was drawn based on the above that there are remarkable differences between open and gated housing blocks on the intensity of residents’ territorial cognition, the level and quantity of their territorial behaviors, and the distribution as well as continuity of the territorial space.

Physical characteristics of residential areas affect many aspects of living sustainability, including the environmental behavior of residents. Based on the policy issued in China in 2016, the guideline of transforming existing gated housing blocks into open mode is being gradually implemented in some cities. However, the transforming of boundary walls and internal roads has changed the living environment such as the open space that residents have been accustomed to and has affected environmental behaviors correspondingly. From perspectives of spatial types and environmental behaviors, this research compared an open housing block (which is reconstructed from gated one) with a comparable original gated housing block. The Behavior Mapping Method was used to capture environmental behaviors in two housing blocks; factor analysis and cluster analysis were used to extract spatial characteristics and classify spatial types; and finally differences between the open housing block and the gated housing block were shown by comparing the distribution of environmental behaviors in each space type. The results indicate that the presence or absence of the enclosing walls affects the division of space types and environmental behaviors in housing blocks. For gated housing blocks, spaces with strong privacy attract various types of activities, which are overwhelming in categories and the number of people, while in the open housing blocks, this situation is not as obvious as in the former.