**3.2 System boundary and LCI data collection**

The system boundary is the evaluation scope of the LCA, and the material consumption and waste discharge within the system boundary are the substance list. When conducting LCA evaluation of products or behaviors, the related upstream and downstream processes are very intensive. Some process factors participate in system construction, but the environmental impact on the system is limited, or the environmental impact data is not clear. In order to avoid interference with the accuracy of the evaluation results, these processes are generally excluded from the system boundary. **Figure 4** is a systematic flowchart of urban green space maintenance. The plant combinations of green space are divided into four layer

*The plant combinations in urban green space.*

subsystems of trees, shrubs, ground cover and turf based on the difference in maintenance work (**Figure 5**).

**Figure 4** shows that the upstream of the system mainly contains the production and sales of the maintenance materials. This part of the list can be obtained by referring to the CLCD or by referring to the same LCA evaluation results. However, the upstream data is mostly the market average, and there may be large deviations [41]. In the system downstream, due to the different waste recycle ways taken by the different maintenance teams, the environmental impact list is difficult to obtain. Therefore, The LCA of green space maintenance system mainly includes onsite energy consumption and emissions. The list of this part comes from on-site investigation and has high reliability, which is also a direct reflection of the environmental impact of maintenance.

#### **3.3 Characterization model of environmental impact in urban green space maintenance**

Based on the general characterization model of LCA, using the equivalent coefficient of energy consumption and global warming potential (GWP) or climate warming potential, we establish an environmental impact characterization model of the maintenance material input and GHG emission inventory:

$$EC\_{\rm g} = \sum\_{i}^{n} \alpha\_{\epsilon i} \times A\_{wi} \tag{4}$$

*Aγa*, *Bγa*, and *Cγ<sup>a</sup>* are the emission amount of climate warming factors CO2, CH4,

and N2O in the system boundary, respectively. *Aαci*, *Bαci*, and *Cαci* refer to the

**4. The quantification of environmental impact in urban green space**

The research area of quantification of urban green space maintenance environmental impact was located in Zhengdong New District, Zhengzhou (China). The

equivalent coefficient of CO2, CH4, and N2O, respectively.

*The research sites in CBD area of city Zhengzhou. Resource: http://map.tianditu.com/*

**maintenance**

**Figure 6.**

**Figure 7.**

**229**

*The sample plots in research sites.*

**4.1 Introducing of research area**

*Sustainable Design in Urban Green Space DOI: http://dx.doi.org/10.5772/intechopen.90026*

*ECg* refers to the characteristic quantity (MJ) of urban green space management resource and energy consumption. *αei* represents the resource and energy consumption equivalent coefficient of the species *i* list in the system. *Awi* refers to the input amount of the *i* substance in the system.

The calculation of the *Awi* value of petrol- and diesel-powered maintenance equipment can be obtained by the following formula:

$$A\_{wi} = \sum\_{a}^{n} \frac{M\_{wa}}{E\_{ea}} \times \beta\_a \tag{5}$$

where *a* is the maintenance equipment associated with the maintenance substance *i* in the system. *Mwa* refers to the workload of the maintenance equipment within the system boundary. *Eea* and *β<sup>a</sup>* represent the working efficiency and fuel consumption per time unit.

The calculation method of the GWP potential (kg/CO2) *EIg* of urban green space management is as follows:

$$EI\_{\rm g} = \sum\_{i}^{n} a\_{i\rm i} \times A\_{\rm wi} + EI\_{\rm eg} \tag{6}$$

*αci* is the GWP equivalent coefficient of the *i* input in the system. *EIeg* is the GWP characteristic quantity of the maintenance equipment used in the system boundary, which can be calculated by the following formula:

$$EI\_{\rm cg} = \sum\_{a}^{n} \frac{M\_{ua}}{E\_{\rm et}} \times \left( A\chi\_{a} \times Aa\_{ci} + B\chi\_{a} \times Ba\_{ci} + C\chi\_{a} \times Ca\_{ci} \right) \tag{7}$$

*Sustainable Design in Urban Green Space DOI: http://dx.doi.org/10.5772/intechopen.90026*

*Aγa*, *Bγa*, and *Cγ<sup>a</sup>* are the emission amount of climate warming factors CO2, CH4, and N2O in the system boundary, respectively. *Aαci*, *Bαci*, and *Cαci* refer to the equivalent coefficient of CO2, CH4, and N2O, respectively.
