5.3. Nature based solutions

residential buildings in form of whole neighborhoods LEED for Neighborhood Development was created to inspire and assist in the development of better, more sustainable, and wellconnected communities. It considers entire communities in addition to building scale. There are two levels of LEED for Neighborhood Development. The first one focus on plan phase. Neighborhood-scale project can be certified if it is currently in any stage of planning and design and is up to 75% complete. The second one focus on designed for neighborhoodscale projects that are nearing completion or have already been finished (within the last three years)36 . All these solutions strongly rely on compact forms of urban structures with traditional elements of a city.

City squares have long served as focal points for local communities' social, cultural, and economic activities. They used to be primarily locations for the exchange of commodities, services, and information, but now they are primarily used for recreational purposes in residential areas as their local community centers. Each district's square should serve as a gathering area, surrounded by the most important public utility, cultural, service, and retail facilities, as well as residential buildings.

The principle should be the openness and permeability of all housing estates as well as the availability and multifunctionality of places used constantly for various purposes, by different users. The share of the housing function is of key importance. The constant presence of people increases safety and a sense of security. Monofunctional spaces, not integrated with the city structure, including industrial parks, shopping and administrative centers, and closed housing estates, are depopulated times of the day or night. Fences, cameras, police and fire patrols are not as effective in the face of a crime threat as the presence of residents who they can appear on the street or in the window at any time.

Considering high level of quality of life that we should ensure to citizens and increasing environmental pressures by extreme events, one of the most important strategic goals of urban planning is to maintain right proportions between built-up and green areas in residential neighborhoods. Green areas, or wider, green infrastructure or blue-green infrastructure all fits to the umbrella concept of nature based solutions (NBS). NBS are defined as actions to address societal challenges through the protection, sustainable management and restoration of ecosystems, benefiting both biodiversity and human well-being. NBS have to be economically viable, resource-efficient, provide environmental and social benefits, adapted to local conditions, and as a result they should support adaptation to climate change. Based on the approach proposen in the project Nature4Cities there are three groups of NBS types that can be distinguished: objects, activities, and strategies. Similarily NBS can be delimited into technological units, spatial units, and supporting units or interventions [4].

Especially NBS objects and strategies are those two groups that should be considered in sustainable urban planning and designing.

The first group of NBS are objects. Depending on a level of description it could be possible to refer to various details and names or definitions which differ in approaches used by some researchers. Some examples of NBS objects are:

• Green roofs (intensive or extensive), • Green walls (climber green wall, planter green wall or green wall systems/living walls), • Vegetated pergolas, • Constructed wetlands for water treatment, • De-sealed areas, • Floodplains, • Swales, • Renaturation of rivers and streams (meander geometry, vegetation on riverbanks), • Urban meadows, • Urban farming (including vegetable gardens, urban orchards or vineyards), • Unsealed and planted parking lots, • Green tram tracks, • Street trees, • Urban greenery (including pocket parks, large urban parks and forests).

Activities that can be considered as a separate group of NBS are: using fauna in urban systems (maintaining beehives, locating hotels for insects, use of grazing animals to maintain green areas), composting, interventions in greenery management to increase biodiversity. NBS activities do not appear usually at the city planning level, but as complementary actions support city management and the use of elements of urban ecosystem.

The last group strictly connected with sustainable urban planning are NBS strategies. In this group we can distinguish protection and conservation strategies (zoning regulating specific land uses that are permitted, limiting or preventing access to selected areas to maintain natural processes) and urban planning strategies (connectivity of ecological network, equal distribution of public green spaces around the city, planning tools to control urban expansion on rural or natural areas (including green belts)). Examples of NBS are presented in Figure 1.3.