An Analysis of the Most Adopted Rating Systems for Assessing the Environmental Impact of Buildings

Rating systems for assessing the environmental impact of buildings are technical instruments that aim to evaluate the environmental impact of buildings and construction projects. In some cases, these rating systems can also cover urban-scale projects, community projects, and infrastructures. These schemes are designed to assist project management in making the projects more sustainable by providing frameworks with precise criteria for assessing the various aspects of a building’s environmental impact. Given the growing interest in sustainable development worldwide, many rating systems for assessing the environmental impact of buildings have been established in recent years, each one with its peculiarities and fields of applicability. The present work is motivated by an interest in emphasizing such differences to better understand these rating systems and extract the main implications to building design. It also attempts to summarize in a user-friendly form the vast and fragmented assortment of information that is available today. The analysis focuses on the six main rating systems: the Building Research Establishment Environmental Assessment Methodology (BREEAM), the Comprehensive Assessment System for Built Environment Efficiency (CASBEE), the Deutsche Gesellschaft für Nachhaltiges Bauen (DGNB), the Haute Qualité Environnementale (HQETM), the Leadership in Energy and Environmental Design (LEED), and the Sustainable Building Tool (SBTool).


Introduction
Rachel Carson's book Silent Spring (1962), in which she describes the powerful-and often negative-effect humans have on the natural world, gave birth to the modern environmental movement. Initially, the environmental movement was mostly concerned about toxics such as Dichlorodiphenyltrichloroethane (DDT) and other pesticides. Later, the focus shifted to air pollution, such as acid rain, and there is a current focus on the continued global warming and the accumulation of plastics in the oceans. Awareness of the damage being done to the planet has gradually pushed scientists and policy-makers to struggle with the problem of climate change (among other issues) because of anthropic activity. In this regard, the concepts of sustainable development [1] and sustainability, which are closely related to each other, were introduced into public discussion. However, the definition of sustainable development introduced by the Brundtland Report has been criticized for its focus on continued economic growth in a limited world [2,3], in opposition to the theories on limits to growth [4,5]. So far, economic growth has been almost directly correlated with the exergy from fossil fuel combustion [6]. Thus, continued industrialization and technological development, conceived as human The aim of the TBL is to consider the impact of resource consumption and the value creation in terms of integration among the three dimensions, assuming that each of them is equally important.
According to the Western Australia Council of Social Services [9], social sustainability is the capacity to provide a good quality of life by creating healthy and livable communities based on equity, diversity, connectivity, and democracy. This moral capital requires the maintenance and the replenishment of shared values and equal rights. Human capital is accepted today as part of economic development [10]. In this regard, it is necessary to define economic sustainability as the optimal employment of existing resources, so that a responsible and beneficial balance can be achieved over the long-term to reach the preservation of the capital. Economic sustainability concerns the real economic impact that a society has on its economic environment. The final definition to complete the triad of the TBL is environmental sustainability. It is defined as the capacity to use natural resources without exceeding their regenerative capacity and protecting the "natural capital" to prevent harm to humans and the environment. This means constraining the scale of the human economic system within the biophysical limits of the overall ecosystem on which it depends; therefore, environmental sustainability is inherently linked with the concepts of sustainable production and sustainable consumption [9].
Going into the details of the TBL framework, and based on the three sustainability dimensions, a wide variety of rating systems have been developed for assessing the environmental performance of buildings, and these are currently available on the market.
These tools have been proposed by different research institutions and have been shaped to reflect specific needs. Crawley and Aho [11] provided the first comparison between some of the major environmental assessment methods in 1999. They focused on the building sector and assessed the environmental sustainability specifically by comparing the scopes of four schemes and identifying general trends. Later, a milestone in categorizing tools was carried out in 2008 by The aim of the TBL is to consider the impact of resource consumption and the value creation in terms of integration among the three dimensions, assuming that each of them is equally important.
According to the Western Australia Council of Social Services [9], social sustainability is the capacity to provide a good quality of life by creating healthy and livable communities based on equity, diversity, connectivity, and democracy. This moral capital requires the maintenance and the replenishment of shared values and equal rights. Human capital is accepted today as part of economic development [10]. In this regard, it is necessary to define economic sustainability as the optimal employment of existing resources, so that a responsible and beneficial balance can be achieved over the long-term to reach the preservation of the capital. Economic sustainability concerns the real economic impact that a society has on its economic environment. The final definition to complete the triad of the TBL is environmental sustainability. It is defined as the capacity to use natural resources without exceeding their regenerative capacity and protecting the "natural capital" to prevent harm to humans and the environment. This means constraining the scale of the human economic system within the biophysical limits of the overall ecosystem on which it depends; therefore, environmental sustainability is inherently linked with the concepts of sustainable production and sustainable consumption [9].
Going into the details of the TBL framework, and based on the three sustainability dimensions, a wide variety of rating systems have been developed for assessing the environmental performance of buildings, and these are currently available on the market.
These tools have been proposed by different research institutions and have been shaped to reflect specific needs. Crawley and Aho [11] provided the first comparison between some of the major environmental assessment methods in 1999. They focused on the building sector and assessed the environmental sustainability specifically by comparing the scopes of four schemes and identifying general trends. Later, a milestone in categorizing tools was carried out in 2008 by Haapio and Viitaniemi [12] in which the schemes are classified by building types, users, phase of the life cycle, databases accessed, and the form in which the results are presented, such as graphs, tables, grades, certificates, and reports. In the same year, Ding [13] proposed an overview of the role of the building assessment methods in developing a sustainability index that might be used for assessing projects and then for setting out a conceptual framework for appraising projects. Recent works have been published by Berardi [14,15], Todd, et al. [16], Abdalla, et al. [17], and provide a discussion on the topic from different perspectives.
The scope of this paper is to collect the widest range of available information from technical manuals and official websites and via direct relationships with agents on the boards of companies or institutions that created these assessment tools. The main contributions offered by this paper are the analysis of many rating systems for buildings that were collected from different sources, the reconstruction of their chronological evolution and geographical distribution worldwide, and the thorough comparison and analysis of the six most studied and adopted rating systems. Moreover, the scoring mechanisms of these six rating systems are presented.
The paper is divided into six sections. The first describes the concepts underlying the environmental assessment schemes. The second section summarizes the two main approaches for assessing building sustainability performance: rating systems and life cycle assessment. Appendix A collects a large number of schemes and tools and provides information about their year of introduction, promoting countries, and owners/administrators. The list of rating systems listed in Appendix A may not be exhaustive, although a wide range is included. The material and methods adopted to develop this paper are presented in Section 3. After the establishment of four selection criteria, six rating systems were selected and are presented in detail in Section 4. Section 5 is dedicated to the analysis and comparison of the six selected schemes based on several criteria such as project type, building type, life cycle phase, and scopes, arranged considering all the aspects involved in environmental performance evaluation. A summary of the primary contributions of this paper is presented in the last section.

Overview of Environmental Assessment Schemes for Buildings
During the last 20 years, there have been significant developments in the investigation of the impact of buildings on the environment. The common tendency has been to establish an objective and comprehensive methodology for assessing a broad range of environmental impacts caused by a building or even a group of buildings. The purpose of these schemes is to measure the environmental sustainability of a built environment in a consistent and comparable manner, with respect to pre-established standards, guidelines, factors, or criteria [18]. The two main approaches that have been used to design environmental assessment schemes for buildings are life cycle assessment (LCA) and building assessment methods or rating systems. In some applications, both of these approaches were combined [11,16].
In this paper, we only focus on the analysis of rating systems and do not carry out an in-depth investigation of LCA tools that are mostly designed to estimate the embodied energy or equivalent emissions related to materials and products. Brief information on both rating systems and LCA tools are presented in the subsequent two sections.

Life Cycle Assessment
The life cycle assessment is a method for examining the environmental impact of a material, product, or process throughout its whole life cycle [19,20]. This procedure of assessment-in some cases considered more objective than others-appraises in a quantitative way all the exchange flows between the products and the environment in all the transformation processes involved. It can be applied to a wide spectrum of fields, including the building industry.
LCA is distinguishable in two approaches that are called attributional LCA and consequential LCA. Attributional LCA focuses on the analysis of the physical environmental impact from a life cycle perspective, while consequential LCA analyzes how this environmental impact will change in response to possible decisions [20]. In both approaches, LCA can be implemented in a wide range of software available on the market, and the type of assessment to be done will dictate which software is used [21]. LCA has been used since 1990, and specifically, current regulations introduce the cradle-to-grave as the common way to state the attributional LCA. For instance, the international standard ISO 14040 declares: "LCA studies the environmental aspects and potential impact throughout a product's life (i.e., cradle-to-grave) from raw material acquisition through production, use and disposal. The general categories of environmental impacts needing consideration include resource use, human health, and ecological consequences" [22]. LCA is, hence, a systematic analysis that can be used to evaluate the alternatives for environmental improvement as a support for the decision-making process. The system boundaries of the building's LCA can be of three types: cradle-to-grave, cradle-to-gate, and gate-to-gate. The cradle-to-gate approach is an assessment of a partial life cycle of a product, from resource extraction to the factory gate, before the product is transported to the consumer. It is usually used as a basis for the environmental product declaration [23]. The gate-to-gate approach is a partial analysis that looks at only one process in the entire production chain. Information about each gate-to-gate module can be linked accordingly in a product chain, including information about the extraction of raw materials, transportation, disposal, and reuse, to provide a full cradle-to-gate evaluation. The cradle-to-grave approach is the most used because it starts from the pre-use phase, including raw material acquisition, goes through manufacturing and transportation to site, and terminates with the end-of-life phase, which includes demolition, recycling potential, landfill, and reuse [24].
In recent years, the consequential LCA has been increasingly used in the building industry and construction sector, but this study concentrates on the rating systems for assessing the environmental performance of buildings, so both attributional and consequential LCA approaches are outside its scope.

Rating Systems for Assessing the Environmental Performance of Buildings
The rating systems for assessing the environmental performance of buildings are intended to establish an objective and comprehensive method for evaluating a broad range of environmental performance. The aim of these schemes is to measure the performance of a building in a consistent and harmonized manner with respect to pre-established standards, guidelines, factors, or criteria. Scoring methods [25] have been used the most to create rating systems for assessing the environmental sustainability of buildings and are based on four major components:

•
Categories: these form a specific set of items relating to the environmental performance considered during the assessment; • Scoring system: this is a performance measurement system that cumulates the number of possible points or credits that can be earned by achieving a given level of performance in several analyzed aspects; • Weighting system: this represents the relevance assigned to each specific category within the overall scoring system; • Output: this aims at showing, in a direct and comprehensive manner, the results of the environmental performance obtained during the scoring phase.
This structure is used by all rating systems for assessing the environmental impact of buildings, but when the details are examined specific adaptations may diverge in several significant parts.

Rating Systems for Assessing the Environmental Impact of Buildings in the World
The Building Research Establishment Environmental Assessment Method (BREEAM) was the first scheme aimed at assessing the environmental impact of a building. It was introduced in 1990 [26,27], and, since then, the field of the rating systems for assessing the environmental impact of buildings has been subject to a rapid increase in the number of schemes developed and introduced on the market worldwide [12]. This phenomenon seems to have reached stabilization in the last few years ( Figure 2).  Table A1, shown in Appendix A, lists more than 70 sustainable building assessment systems released worldwide, including LCA schemes and the rating systems, and provides additional information. Figures 2 and 3 graphically represent the data collected in Table A1, exploiting their temporal evolution and their geographical distribution. The highest rate of introduction of new schemes was registered between 1995 and 2010. After 2010, the rate went down. The rating systems represent the larger share of all schemes presented worldwide and show a logistic growth. Conversely, the trend of the LCA schemes develops quite linearly.   Table A1, shown in Appendix A, lists more than 70 sustainable building assessment systems released worldwide, including LCA schemes and the rating systems, and provides additional information. Figures 2 and 3 graphically represent the data collected in Table A1, exploiting their temporal evolution and their geographical distribution. The highest rate of introduction of new schemes was registered between 1995 and 2010. After 2010, the rate went down. The rating systems represent the larger share of all schemes presented worldwide and show a logistic growth. Conversely, the trend of the LCA schemes develops quite linearly.  Table A1, shown in Appendix A, lists more than 70 sustainable building assessment systems released worldwide, including LCA schemes and the rating systems, and provides additional information. Figures 2 and 3 graphically represent the data collected in Table A1, exploiting their temporal evolution and their geographical distribution. The highest rate of introduction of new schemes was registered between 1995 and 2010. After 2010, the rate went down. The rating systems represent the larger share of all schemes presented worldwide and show a logistic growth. Conversely, the trend of the LCA schemes develops quite linearly.  The geographical distribution of the collected tools is as follows: 54 schemes in Europe, 15 in Asia, 8 in North America, 3 in both Oceania and South America, and almost 0 in Africa and Middle Eastern countries. Furthermore, some schemes (e.g., the Sustainable Building Tool (SBTool) and SPeAR) cannot be attributed to any specific country or continent. However, the three schemes available in South America are just a customization of frameworks originally developed in other continents.

Methodology
As already mentioned, this paper focuses on the rating systems. The great majority of data used in this study was acquired directly from the official technical manuals for the rating schemes. Additional material was collected from the official homepages of the certification organizations or from previous scientific review papers. However, the literature concerning the schemes and their structure and content is rather limited and most of the proposed reviews only pertain to applications of the schemes to local case studies. In this paper, the selected schemes were not applied and tested on case studies and the analysis exclusively focuses on the elaboration and evaluation of the officially declared attributes of the frameworks.
For this study, only environmental rating systems for assessing the environmental performance of buildings have been considered and no benchmarking or evaluation software (e.g., ATHENA, BeCost, BEES, Eco-Quantum, Envest 2, EQUER, LEGEP ® , PAPOOSE, ABCplanner, Green Globe 21, BEAT, PLACE3S, SCALDS, SPARTACUS) has been further analyzed. An analysis of a few evaluation tools can be found in [12]. Moreover, among all the rating systems available worldwide, only those that meet all the following four criteria were considered in the subsequent analyses: 1.
An exclusive focus on buildings; 2.
Scientific interest: cited in at least 20 papers reflected in the Elsevier's Scopus database; the search was executed on article titles, abstracts, and keywords. 3.
A consolidated development state: more than 5 years of service.
As shown in Table 1, only six rating systems met the four selection criteria, and will be described in Section 4:
Deutsche Gesellschaft für Nachhaltiges Bauen (DGNB), Germany. Next, these six schemes are thoroughly analyzed in Section 5 to explore similarities and differences between them and to, eventually, identify implications for the design of buildings. To this purpose, the selected rating schemes are grouped into homogeneous categories, and data is compared regarding geographical coverage, design purpose, and requirements, etc. Finally, some general conclusions are drawn.

Description of the Selected Rating Systems
The six selected rating systems are described in this section. Exploitation of categories, scoring, weighting and outputs, the structure, and the main features of each system are presented.

Building Research Establishment Environmental Assessment Methodology (BREEAM)
Conceived in the UK in 1988 by the Building Research Establishment, the Building Research Establishment Environmental Assessment Methodology (BREEAM) was launched in 1990. Currently it has been used in around 556,600 certified buildings all around the world and more than two million buildings have been registered for assessment since its launch in 1990.
The scheme is composed of ten categories describing sustainability through 71 criteria in total. A percentage-weighting factor is assigned to each category, and the overall number of 112 available credits is proportionally assigned. However, there are some constraints on the credit assignment: indeed, a minimum achievement is required for the categories Energy and CO 2 and Water and Waste, which are reported in Table 2 where the categories for each scheme are listed.

Comprehensive Assessment System for Built Environment Efficiency (CASBEE)
The Comprehensive Assessment System for Built Environment Efficiency, usually referred to by the acronym CASBEE, is the Japanese sustainability rating system for buildings. It was developed in 2001 by the Japan Sustainable Building Consortium (JSBC), which is a nongovernmental organization comprising the Japanese government, academic partners, and industry [28]. In 2005, it was launched on the international market and, since 2011, it has become mandatory in 24 Japanese municipalities. CASBEE is structured to have several schemes that depend on the size of a building and address the four main building life phases: • CASBEE for Predesign, for use in site selection and building planning; • CASBEE for New Construction, to be used in the first three years after building completion; • CASBEE for Existing Buildings, to be used after at least one year of operation; • CASBEE for Renovation, which is intended to support a building refurbishment.
To fulfill the specific purposes, CASBEE also features a huge batch of supplementary rating systems that are relevant when the basic version cannot be used, such as detached houses, temporary constructions, heat island effect, urban development, and cities and market promotions.
CASBEE assesses a building project using a metric called building environmental efficiency (BEE), which is given by the ratio between the two metrics built environmental quality (Q) and built environmental load (LR) Q calculates the "improvement in everyday amenities for the building users, within the virtual enclosed space boundary" and LR quantifies the "negative aspects of environmental impact that go beyond the public environment" [29]. Q and LR range between 0 to 100 and are computed based on three subcategories, tabulated on a score sheet, as reported in Table 3. BEE is expressed as the gradient of a line on a graph that has LR on the x-axis and Q on the y-axis. Based on the BEE value, a level of performance (i.e., S, A, B+, B−, and C) is associated with a given project. For additional details, see the CASBEE official website [30]. The values calculated in each category are represented on a radar chart. The assessment results sheet analyses and applies weights, using coefficients for each item and the Q and LR values and produces, as a last step, an overall score conveyed through the BEE index [31]. This index is used to assess the six categories covered by the CASBEE evaluation: indoor environment, quality of service, outdoor environment (on-site), energy, resources and materials, and off-site environment.

Deutsche Gesellschaft für Nachhaltiges Bauen
The Deutsche Gesellschaft für Nachhaltiges Bauen, referred to by the abbreviation DNGB, was developed by the Deutsche Gesellschaft für Nachhaltiges Bauen (German Sustainable Building Council), which was founded in 2007, with the collaboration of the Federal Ministry of Transport, Building and Urban Affairs. The DNGB was lunched in 2009 with the aim of promoting building sustainability in Germany and developing a German certificate for sustainable buildings [32]. The DGNB refers to the Environmental Product Declaration developed according to the standards ISO 14025 [33] and EN 15804 [34] and is mostly based on quantitative measures calculated using the life cycle assessment approach. This evaluation system is flexible and can be applied to national and international environmental assessment, including 13 different building types and, since 2011, entire urban districts. The evaluation is based on 63 criteria, subdivided into six categories that are weighted by a specific weighting factor ( Table 4). The sum of the points obtained in all the categories provides the overall score for the building. Each criterion can receive a maximum of 10 points. Four categories (ecological quality, economical quality, socio-cultural and functional quality, and technical quality) have equal weight in the assessment, while process quality is less important (see weights in Table 4); thus, the DGNB system gives the same importance to the economic, ecological, sociological, and technical aspects of an intervention. Quality of planning and design, construction process, building use and maintenance and quality of the construction activities.
Quality of the location Rated independently Transport-related topics, risks and image of location.
There are some specific minimum requirements that must be considered, such as the indoor air quality and the Design for all requirements included in the socio-cultural and functional quality criterion, and the legal requirements for fire safety and sound insulation included in the technical quality criterion. It is necessary to achieve a minimum required level in each quality section to obtain the evaluation.

Haute Qualité Environnementale (HQE TM )
The Haute Qualité Environnementale standard, referred to by its abbreviation HQE™, was developed in 1994 in France by the HQE™ association [35]. This association supports stakeholders, designers, partners, developers, and users during a project's phases and aims to guarantee a high environmental quality of buildings. The HQE™ Association has developed many schemes, exploitable in France and abroad. It is structured to have three organizations in charge of delivering national evaluations (Certivèa, Cerqual, and Cèquami) and one for supporting the evaluation across the world (Cerway) [36]. HQE™ covers buildings throughout their life cycle, that is, throughout their design, construction, operation, and renovation. It is addressed to nonresidential and residential buildings, and detached houses. Furthermore, a specific scheme for the management system of urban planning and development projects is also available. The environmental performance requirements are organized into four topics that together include 14 categories. Topics are almost the same for all building types, but the targets are arranged differently for residential buildings and nonresidential buildings (i.e., commercial, administrative, and service buildings) (Tables 5 and 6, respectively).  A building project obtains an assessment for each target expressed according to three ordinal levels: basic, performing, and high Performing. To be certified, a building must achieve the high performing level in at least three categories and the basic level in a maximum of seven categories. This rating system does not weight each category by a weighting factor, because they are considered to have the same importance throughout the assessment framework.

Leadership in Energy and Environmental Design (LEED)
The first Leadership in Energy and Environmental Design Pilot Project Program, referred to as LEED ® Version 1.0, was launched in the USA in 1998 by the US Green Building Council (USGB), a nongovernmental organization that includes representatives from industry, academia, and government [37]. Since that time, the LEED ® system has undergone some revisions, integrations, and national customizations. The LEED ® Version 4.0 was released in 2016 and is currently in use. The LEED ® Green Building Rating Systems are voluntary and are intended to evaluate the environmental performance of the whole building over its life cycle. Different schemes are designed for rating new and existing commercial, institutional, and residential buildings. Each scheme has the same list of performance requirements set out in five categories, but the number of credits, prerequisites, and available points change considerably according to the specific area of interest and the building type. Table 7 provides a description of the categories included in the LEED ® environmental rating scheme. Table 7. LEED ® 's categories and description.

Category Description
Sustainable sites This section examines the environmental aspects linked to the building site. The goal is to limit the construction impact and verify meteoric water outflow.

Water efficiency
The section is linked to the water use, management and disposal in the buildings. The reduction of water consumption and meteoric water reuse are promoted.
Energy and atmosphere In this section building energy performance improvement, the use of renewable sources and the energy building performance control are promoted.

Materials and resources
In this area the environmental subjects associated to the material selection, the reduction of virgin material use, the garbage disposal and the environmental impact due to transport are considered.

Indoor environmental quality
The themes considered in this section cover indoor environmental quality, taking into account for example healthiness, comfort, air renewal and air pollution control.

Innovation in design
The aim of this section is to identify the design aspects that improve on the sustainability operations in the building construction.
Regional priority This area has the objective of encouraging the design groups to focus the attention on the local characteristics of the environment.
Almost all schemes present mandatory prerequisites and noncompulsory credits, which can be selected according to the objectives that is to be achieved. The summation of points for each credit generates the evaluation outcome. All the credits receive a single weight according to a precisely defined scoring system.
The scoring system has a maximum score of 100 points, plus there are up to 10 additional bonus points for complying with two special categories. Out of the possible total of 100 points, a minimum of 40 points should be obtained to pass the basic evaluation.

SBTool
In 1996, the international Green Building Challenge initiative, which was later named the Sustainable Building Challenge, set the goal of establishing energy and environmental performance standards that would be suitable in both international and national contexts. It was therefore necessary to identify assessment tools that, through different methodological bases, would be able to objectively assess the requirements of the environmental, economic, and social impacts of a building during its entire life cycle.
Developed by the work of representatives from 20 countries, this process led to the so-called SBMethod that was designed to offer, besides a common international standard, an easy customization with respect to individual national contexts. This method is continually updated by a technical committee managed by the International Initiative for a Sustainable Built Environment (iiSBE). The SBMethod covers the three aspects of sustainability (i.e., environmental, economic, and social impacts) from the building perspective and can be used to assess every design concept or existing building independently from its prevalent use and geometrical extension, according to the four phases: predesign, design, construction, and operation.
Originating from the SBMethod, the Green Building Tool (GBTool), as it was initially called, was later renamed the Sustainable Building Tool (SBTool). The SBTool is a generic framework for rating the environmental performance of a building by assigning scores and credits for a number of areas [38]. The method is structured in a way that means that each parameter is defined with a weight. It is a weighted assessment where the weighting factors are different for different building types, such as single buildings, residential buildings, commercial buildings, new-builds and existing constructions, or a mix of the two. The performance issues and the phases of the life cycle used for the assessment are listed in Table 8.
The system provides separate modules for the site and building assessments, carried out in the predesign phase, and the building assessments, done in the design, construction, or operation phases [39]. The performance framework of SBTool is organized into four levels, namely: (1) performance issues, (2) performance categories, (3) performance criteria, and (4) performance subcriteria [40]. Each performance issue contains categories that represent the domain in a more detailed and specific manner.

Comparative Analysis of the Selected Rating Systems
As already mentioned, the number of rating systems for assessing the environmental impact of buildings is high, and the goal of this section is to give insights into the subject by the analysis and comparison of a selection of existing schemes. Table 9 summarizes some information about the six schemes selected. How the schemes' categories, similarities, and differences can be exploited is displayed. In the following tables, the schemes are classified according to the following categories: Applied to each category Japan JSBC N/A Complex weighting system applied at every level Germany DGNB
The first analysis aims at contrasting the selected six rating systems for assessing the environmental impact of buildings with respect to the type of intervention (Table 10). While BREEAM, CASBEE, DGNB, HQE™, and LEED ® have dedicated subschemes or modules to cover all the four types of intervention, the SBTool does not provide assessment tools for building refurbishment and urban planning.
Rating schemes can be used to certify the environmental performances of different types of buildings, such as residential, office, commercial, industrial, and educational buildings, and all other buildings that do not fit into any of these building types are grouped in the field called Other types of buildings. It can be seen in Table 11 that BREEAM, CASBEE, DGNB, and HQE TM can be used with all building types. LEED ® and SBTool do not include industrial buildings in their evaluation. Regarding the life cycle phase of a building, BREEAM, CASBEE, DGNB, and HQE TM cover all the four considered life cycle phases of a building. LEED ® does not evaluate predesign or design, and the SBTool does not cover the use/maintenance phase.

Rating System Predesign and Design Construction Post-Construction Use/Maintenance
As a matter of fact, regarding the original categories, different items in two or more schemes often refer to the same field and, sometimes, similar denominations do not assess exactly the same attributes. We have therefore identified eight major scopes, in which the characteristic elements of all the categories have been grouped. According to this analysis, the categories that are the ones most assessed by the schemes are energy performance and solid waste management. Other important categories are materials, water, waste water management, and ecology and environmental quality, which are assessed by the great majority of schemes. The scopes that are assessed the least are those related to resistance to natural disasters, which are considered only by CASBEE, DGNB, and HQE TM . Similarly, the category olfactory comfort is considered only by the schemes in HQE TM , while, in the other systems, it is included in the more general category air quality. Finally, the building information and users guide is considered only by the schemes of the BREEAM collection and in some isolated cases by a few subschemes in LEED ® , HQE TM , and DGNB. In Figure 4, to support the results, the scopes distribution among the schemes is presented graphically.

Conclusions
In this paper, an overview of the available rating systems for assessing the environmental impact of buildings is presented. The rating systems for assessing the environmental impact of buildings are technical instruments that have been developed with the specific purpose of evaluating the environmental performances of buildings. In the last decade, a growing interest in sustainability and sustainable development has been registered due to the urgent requirement for a worldwide reduction in greenhouse gas emissions for the safety of our planet and the health of global society. This has had a remarkable impact on the building and construction industry and, consequently, a wide array of rating schemes has been developed with different purposes and features to enhance buildings' sustainability.
The core of this work is a comparative analysis of six widespread and consolidated schemes that are the most cited in the scientific literature. The present study is motivated by the need to identify differences in the rating schemes to better understand their main features and identify their possible implications. After carrying out a survey of more than 70 schemes for assessing the environmental impact of buildings, the following six schemes were selected and analyzed in depth: the Building Research Establishment Environmental Assessment Methodology (BREEAM), the Comprehensive Assessment System for Built Environment Efficiency (CASBEE), the Deutsche Gesellschaft für Nachhaltiges Bauen (DGNB), the Haute Qualité Environnementale (HQE TM ), the

Conclusions
In this paper, an overview of the available rating systems for assessing the environmental impact of buildings is presented. The rating systems for assessing the environmental impact of buildings are technical instruments that have been developed with the specific purpose of evaluating the environmental performances of buildings. In the last decade, a growing interest in sustainability and sustainable development has been registered due to the urgent requirement for a worldwide reduction in greenhouse gas emissions for the safety of our planet and the health of global society. This has had a remarkable impact on the building and construction industry and, consequently, a wide array of rating schemes has been developed with different purposes and features to enhance buildings' sustainability.
The core of this work is a comparative analysis of six widespread and consolidated schemes that are the most cited in the scientific literature. The present study is motivated by the need to identify differences in the rating schemes to better understand their main features and identify their possible implications. After carrying out a survey of more than 70 schemes for assessing the environmental impact of buildings, the following six schemes were selected and analyzed in depth: the Building Research Establishment Environmental Assessment Methodology (BREEAM), the Comprehensive Assessment System for Built Environment Efficiency (CASBEE), the Deutsche Gesellschaft für Nachhaltiges Bauen (DGNB), the Haute Qualité Environnementale (HQE TM ), the Leadership in Energy and Environmental Design (LEED ® ), and the SBTool.
Data was collected from technical manuals and official websites and, sometimes, through direct relationships with agents on the technical or administrative board of the companies creating these systems. In this regard, we should point out that some challenges were faced during the data acquisition process. User manuals are not always available, and information, even though it is usually publicly disclosed, often appears to be fragmentary or is only available in local languages.
We also noticed that a systematic comparison of the schemes is difficult, sometimes even prohibitive. As a matter of fact, different rating schemes have been developed for different purposes and hence a precise comparison of categories and subcategories is often not achievable.
The analysis has been carried out considering several aspects, and we discovered the following: • All rating systems for assessing the environmental impact of buildings are suitable for both new and existing buildings and, apart from the SBTool, cover the refurbishment of buildings as well; • BREEAM, CASBEE, DGNB, and HQE TM can be used to assess all types of buildings, while LEED ® does not cover industrial buildings and the SBTool is the most limited since it does not cover urban planning projects, and building types other than residential, office, commercial, and educational buildings; • BREEAM, CASBEE, DGNB, and HQE TM cover all the life cycle phases of a building; • SBTool is the only system that has also been designed for certifying a low performance level of a building; • Regarding the categories assessed by the schemes, energy performance, solid waste management, material, and water are the most considered categories from a quantitative perspective; • The categories that are considered less are resistance against natural disasters, earthquake prevention, and olfactory comfort.
In conclusion, it should be noted that these schemes have been largely accepted and widely used in the building sector. Regarding future development of these schemes, desirable features are: • Completeness, that is, analyzing in an appropriate way all the elements characterizing a building and its life cycle; • Representing in a clear way the weighting system and supporting the scoring system with sound evidence. responsibility for the content of this article lies with the authors. It does not necessarily reflect the opinion of the European Commission (EC). The EC is not responsible for any use that may be made of the information this article contains.

Author Contributions:
The work presented in this article is the result of a collaboration of all authors. Elena Bernardi, Salvatore Carlucci, and Cristina Cornaro analyzed the literature on the subject, contributed to writing the manuscript, and edited the document. Salvatore Carlucci, Cristina Cornaro, and Rolf André Bohne critically reviewed the article. All authors contributed to the discussion and conclusions of this research.