# Life Cycle Analysis Challenges through Building Rating Schemes within the European Framework
## 1 Introduction  
### The Global Impact of Buildings  
The decarbonisation of buildings is a crucial milestone if European cities mean to reach their mitigation targets and become sustainable. However, other environmental impact categories are also key in the reduction of the harmful effects of the European construction industry: greenhouse gas (GHG) emissions, abiotic depletion, acidification, eutrophication, energy footprint, water consumption, solid waste production, or the various social impacts. The new circular economy (CE) plans boost the reduction of these impacts, especially in terms of waste management [1]. This and other strategies bring life cycle assessment (LCA) to the forefront of the European buildings' framework.  
The construction sector is responsible for 39% of the GHG emissions [2], updated to 38% in 2020 [3]. From these emissions, 11% is calculated to be currently embodied in building materials and released before the infrastructures are used. Concrete, iron, and steel alone are responsible for ~9% of this 11%. Additionally, according to the Global Alliance for Buildings and Construction [4], in the 2010-2018 period, the newly built area increased by24%, while GHG emissions and PE grew at a lower rate (by 6%). It has been estimated that embodied GHG emissions could reach up to 50% of the total emissions of the construction sector by 2050 [2]. Being aware of the need for decarbonisation throughout all the life stages of a building, 2010 in Europe was marked by the first version of the Energy Performance of Buildings Directive (EPBD) [5], which made it mandatory for all new buildings to be Nearly Zero Energy (NZEB) by 31 December 2020 [6]. For decarbonisation and energy efficiency purposes, rating systems, performance standards, and a plethora of databases, codes, regulations, and building solutions need to become part of the designing, erecting, and managing of buildings [7].  
The construction sector also accounts for 36% of global primary energy (PE) use, meaning that international efforts need to be made in this sector in order to meet the global climate ambitions set forth in the Paris Agreement [8]. They have also estimated that by 2030 the energy intensity per square meter must be reduced by 30% in relation to the 2015 values. While energy efficiency policies are successful during the use-stage of buildings, the sector has recently started to take into account the embodied carbon emissions and energy consumption of building materials and building processes, which have seen rapid growth since 2015 [9]. Integration of the analysis of embodied energy impacts is still barely integrated within LCA in points 9, 10, and 11 of the EN15978 [10]. When this applies to building products, the EN15804 or environmental product declaration (EPD) is particularly noteworthy.  
Concerning construction and demolition waste (CDW) generation, the European Union (EU) construction sector produced 923 million tons of waste in 2016 [1]. This represents the largest waste stream in the EU--30% of all waste generated, of which scarcely half was recycled (with a 70% target) [1]. Although the EU's circular economy strategy is improving the situation, the LCA of CDW is being applied, and the overall landscape of construction stakeholders lacks internal common drivers [11].