**4. Results**

In this study, we obtained a heating requirement of 15.4 kWh/m2·year. The main requirement for meeting passive standards is to have a heating requirement of less than 15 kWh/m2·year. We notice that some buildings do not respect the passive standard. This may be due to their wrong orientation. The average results of the LCA under building scales are shown in Table 4. These results showed that in the studied buildings, after 80 years, the average greenhouse gas was expected to be 2586.1 tCO2 eq, while the cumulative energy demand would be 73,935.2 GJ.


**Table 4.** Average LCA results for the buildings in terms of calculated impacts.

The radioactive waste would increase to 76.5 dm3. The waste water was from 58.593 m3 /inhabitant per year. According to the research of Marique and Reiter [24], heating energy was estimated to be between 190 and 200 kW h/m2, in the case of the conventional neighborhood. In this case, the heating energy is around 16 kW h/m<sup>2</sup> as requested by several international standards. Moreover, according to Lotteau et al. [29], the greenhouse gas is between 11 and 124 kgCO2/m2; in this research, it is around 35 kgCO2/m2. This means that the results found in this research are in the range given in the literature.

The average odor concentration was 32.162 Mm3air/inhabitant per year. Table 5 shows some simulation results of the LCA on the neighborhood scale. It was seen that the total greenhouse gas was expected to be 21,733.64 tCO2 eq after 100 years, whereas the total cumulative energy demand was 532,385.49 GJ. The health damage was 22.29 DALYS (disability-adjusted life years), and the potential for degradation related to land use obtained was 28,630.00 m2/year.

DALYs are the sum of the YLDs and YLLs, per disease category or outcome, and per age and sex class:

$$\text{DALY} = \text{YLD} + \text{YLL} \tag{1}$$

where YLD (the morbidity component of the DALYs) = number of cases \* disease duration \* disability weight; YLL (the mortality component of the DALYs) = number of deaths \* life expectancy at age of death.

It was interesting to notice that the total eutrophication assessed was 42,794.03 kg PO4 eq. The analysis of the most important sources of impact (greenhouse gas and cumulative energy demand) and their distributions according to the different stages of the life cycle is given in Figures 6 and 7. In Figure 6, we notice the strong predominance of the occupation phase, which concentrates on 93% greenhouse gas production. In this phase, mobility is strongly in the majority with 46% emissions. Heating and domestic hot water accounts for 24% of emissions, while waste treatment accounts for 15% of the emissions during the use phase. Only 1% of greenhouse gas comes from a "public space". It is interesting to note that emissions from the household waste management are equivalent to those from the production of hot sanitary water (15% of the use phase emissions), whereas the emissions from heating accounted for only two-thirds of the emissions, from the production of hot sanitary water.


**Table 5.** LCA results at the neighborhood scale (initial case).

**Figure 6.** Detailed results of the calculation of the "greenhouse effect" impact at the neighborhood level (initial case).

**Figure 7.** Detailed results of the "cumulative energy demand" impact calculation at the neighborhood scale (initial case).

Emissions due to the mobility of the inhabitants accounted for almost half of the emissions from the use phase. These characteristics were perhaps due to the fact that the high thermal performance of our buildings greatly reduced their heating consumption. Figure 7 showed the impact of cumulative energy demand defined in [61] .As in the previous Figure 6, it was seen in this figure that the use phase was predominant (96% of the cumulative total energy demand). This could be due to the accounting for mobility and waste management. The cumulative demand for energy due to waste management was almost identical to that due to the mobility of residents and was equivalent to almost one-third of the demand of the occupancy phase. In addition, this was because the cumulative energy demand from transportation and waste management during the use phase was 60% of the total cumulative energy demand of the neighborhood, over its entire life cycle. Meanwhile, the cumulative energy demand due to "the heating and domestic hot water" was only half of that required for the transport of inhabitants or the management of household waste. These different results show a very strong participation of the mobility component and the household waste management component in the LCA at the neighborhood level.

#### *4.1. Orientation Impact Assessment*

This section studied the orientation impact assessment of the LCA outcomes at the neighborhood level. Figure 8 showed the comparison of the environmental impacts of the established scenarios to "0◦ orientation" and "90◦ orientation", in percentage. We noted that once all the neighborhood-level impacts were accounted for, the influence of the orientation became minimal. Indeed, it was mainly on the greenhouse effect, on the cumulative demand of energy, and on the depletion of the abiotic resources that the orientation had an important effect. This was due to the change in energy consumption due to heating. However, we observed only a relative increase of less than 1% of these impacts. Moreover, this evolution only affected the phase of use. On the other hand, we observed a 1% increase in greenhouse gas emissions, as well as the depletion of abiotic resources and cumulative energy demand during the use phase in the case of a rotation to 90◦. This is could be due to the increase in gas consumption caused by the increase in heating needs.

**Figure 8.** Comparison of the environmental impacts of the "0◦ orientation" and "90◦ orientation" scenarios (functional unit: entire neighborhood), in percentage.

Comparing the scores of the environmental indicators only for the heating items during the use phase, as also for both orientations, we notice an 11% increase in the greenhouse effect, as well as a cumulative energy demand and depletion of abiotic resources for the 90◦ orientation. Thus, the orientation has an impact on heating consumption and on environmental indicators relating only to these [62–65]. However, at the neighborhood level, this orientation has little impact on the overall results of the LCA. However, even if the orientation has little influence on the LCA results at the neighborhood level, at the building level it can be decisive, especially for obtaining the passive label.

The different quantities of environmental impacts are shown in the Table 6.


**Table 6.** Details of orientation scenario per square meter. (1) Greenhouse gas; (2) acidification; (3) cumulative energy demand; (4) waste water; (5) waste products; (6) depletion of abiotic resource; (7) eutrophication; (8) photochemical ozone production; (9) biodiversity damage; (10) radioactivity waste; (11) health damage; (12) odor.

### *4.2. Water Management Impact Assessment*

In Figure 9a, we note that setting up rainwater harvesting systems has a strong impact on certain environmental indicators. Indeed, collecting all the rainwater can reduce eutrophication by 32%. This significant decrease is due to the fact that the runoff water is entirely recovered on the site by the valleys and infiltration basins. Thus, the nutrients are not strained, but retained on the site. On the other hand, it was noticed that drinking water consumption is also strongly impacted. Indeed, with a well-sized tank, it is possible to use only rainwater to feed the washing machines and flushes with water. This will save drinking water up to 6000 L per person per year, which implies a 14% reduction in water consumption of the neighborhood on a scale of its total life cycle—a 7% decrease in waste produced over the entire life cycle of the neighborhood. Indeed, on the use phase, 15% less waste is produced. This is the runoff water that is no longer directed to the treatment plants, and therefore no longer needs to be treated. Moreover, we have observed a decrease of about 4% in damage to biodiversity, damage to health and acidification.

The analysis in Figure 9b shows that the impact of soil permeability on the total LCA of the neighborhood is lower. In fact, the concerned indicators are still eutrophication and waste production. In this case, the use of permeable soils reduces the impact of eutrophication by 5% and the production of waste by 1% over the entire life cycle of the neighborhood. In fact, the amount of water that infiltrates into the ground, thanks to the permeable pavements, is less than the quantity that can be recovered by the recovery systems presented in the previous scenario. Figure 10 shows the comparison of the three scenarios (initial scenario, and with and without permeable floor coverings). The analysis of this figure shows that it is more efficient to install recovery systems like cisterns, valleys or infiltration basins at the neighborhood level. However, implementing permeable floor coverings on areas that cannot benefit from recovery systems will have a positive impact on the amount of wastewater to be treated and on eutrophication.

**Figure 9.** Comparative diagram of the environmental impacts of scenarios with and without rainwater harvesting systems (**a**), and with and without permeable floor coverings (**b**) (functional unit: entire neighborhood), in percentage.

**Figure 10.** Comparative diagram of the environmental impacts of the initial scenarios, with and without permeable floor coverings (functional unit: entire neighborhood), in percentage.
