International Conference on Natural Science and Environment, New York, USA 16th- 17th July, 2019 1 Abstract— Life Cycle Analysis (LCA) is the most appropriate method to quantify scientifically the environmental and health impacts of buildings. The purpose of this research is to determine, at the neighborhood scale, the most important sources of buildings’ environmental impacts, based on twelve different environmental impacts including the health impact. This paper compares the impacts on the environment generated by an existing energy efficient neighbourhood, where all the buildings should be passive, and its transformation into a zero-energy district thanks to the addition of numerous photovoltaic panels on the roofs of the buildings. For that, we used the combination of three simulation tools — ALCYONE, COMFIE-PLEIADES and nova-EQUER for studying the Life Cycle Assessment (LCA) of buildings and networks (roads, parking, etc). An eco-neighbourhood, located near the University of Liege in Belgium, has been selected as the case study. The buildings heating modelled by the dynamic thermal simulation has an average heating load of 15.4 kWh/m².year.Photovoltaic panels on all the roofs of the buildings allow achieving a nearly zero-energy neighbourhood and can mitigate up to 25% of greenhouse gas emissions of the passive neighborhood and reduce 5% of its health impacts. However, the photovoltaic panels have a mixed environmental record for other indicators, with a majority of the environmental impacts being improved compared to the passive neighborhood, but four of the twelve environmental impacts studied being increased.We also notice the strong predominance of the occupation phase on the life-cycle environmental impacts of this nearly zero-energy neighborhood. The use phase concentrates more than 70% of the greenhouse gas production and of the cumulative total energy demand of the neighborhood calculated during 80 years. Moreover, the results show a very strong participation of the mobility component and the household waste management component, in the LCA, at the neighbourhood level. The cumulative energy demand from inhabitants’ mobility and waste management during the use phase was 60% of the total cumulative energy demand of the neighbourhood, over its entire life cycle. The results show also that an improved mobility management allows reducing all the environmental impacts of the neighborhood and may reduce its health impacts up to 32%. Key-words : Life cycle assessment, urban scale, zero-energy neighborhood, health impact, environmental impacts. I. INTRODUCTION The building sector is one of the sectors that consume the most natural resources, especially fossil fuels. It induces enormous environmental impacts [1]. The strong environmental impact of the residence building sector has been well understood by the European authorities. For this, several new regulations came into force, aimed for reducing energy consumption of new buildings. These regulations are more and more demanding. However, they only target one scale, that of the building, which concerns only one indicator, the energy consumption and only one stage of the life cycle, the occupation stage[2].Beyond the building scale, the zero-carbon city concepts , city without CO2, or post-carbon city are emerging around the world. Cities are concentrating more and more population, they now welcome 50% of humanity. According to Colombert et al. [3], Cities are becoming aware of the need to preserve biodiversity and green spaces. In the literature, it is stated that the transport sector is responsible for 31% of overall final energy consumption, and the industry sector for 27%. However, the biggest consumer in many countries is the building sector. It is recommended that in order to reach the energy efficiency targets, wished by the European Commission, all energy consuming sectors must evolve and take ambitious measures[4-5] . The life cycle assessment (LCA), allows achieve different types of comparative studies to be conducted. Indeed, this method also makes it possible to quantify the environmental impact on the complete life cycle of a product or only on one stage of the cycle without necessarily making a comparison. Thus, it is a tool that can serve as a decision aid but also allows to target the phases of the life cycle of a product that would need to be reworked with an eye to the environment. Many sustainable building certification schemes are based on LCAs of building materials [6]. Life cycle assessment of a nearly zero-energy neighborhood in Belgium Modeste Kameni Nematchoua 1,2* , Sigrid Reiter 2 1 Beneficiary of an AXA Research Fund postdoctoral grant, Research Leaders Fellowships, AXA SA 25 avenue Matignon75008 Paris, France. 2 Management & Analysis (LEMA), Allée de la Découverte9, Quartier Polytech 1, BE-4000 Liège, Belgium. Email : 1,2* mkameni@uliege.be , 2 sigrid.reiter@uliege.be