3.3 Selection criteria and list of KPIs

A detailed literature review was first carried out to identify and map relevant scientific areas and criteria addressing environmental issues related to the built environment in line with (i) relevant Sustainable Development Goals (SDGs) of the United Nations (UN) 2030 Agenda for Sustainable Development (UN, 2015b), including the SDG 6 to preserve clean water, the SDG 7 for affordable and clean energy, the SDG 11 for sustainable cities and communities, and the SDG 12 for responsible consumption and production patterns through resource and energy efficiency, and (ii) EU efforts contributing to the implementation of these goals through policies and initiatives (Eurostat, 2024a) channelling global environmental challenges.

The selected KPIs and their corresponding indicators relevant to the environmental perspective of the Sustainability dimension were derived from a plethora of indicators and metrics that are commonly used in voluntary and commercial rating systems, also known as green building rating systems, based on a multi-criteria approach providing the sustainability assessment of a building to award a corresponding certificate (Mattoni et al., 2018). Specifically, the investigation was focused on both European, e.g. BREEAM (UK), ITACA Protocol (Italy), and non-European, e.g. LEED (USA), Green star (Australia), CASBEE (Japan) rating systems, along with standards on green building design, such as the ASHRAE Standard 189.1 (ASHRAE, 2023a). The work also aligned with Level(s), which is a voluntary reporting framework developed by the European Commission in 2020 to improve the sustainability of buildings based on a common system of indicators (Dodd et al., 2021a). Level(s) is being used in EU policy and other instruments like the EPBD, EU taxonomy and green public procurement, while impacting commercial certification schemes (Donatello et al., 2022). Indeed, the heterogeneity of the available rating systems leads to various drawbacks, such as the difficult comparability of the final score of an assessment. Moreover, the rating systems include distinctive local features specific of the regional characteristics of the area where the tool was developed, limiting their application globally. Only few rating systems provide international versions enabling their application by other countries or regions apart from the origin country, such as BREEAM, and LEED, thus Level(s) represented a significant attempt to overcome the difficulty of managing the extensive heterogeneity of the existing certification schemes. Level(s) effort to develop a holistic transparent and regionally adaptable tool supports circular economy principles in the built environment across the whole life cycle of a building, focusing on GHG emissions, resource efficiency, and water use. Level(s) complements the NEB initiative by identifying measures to improve the sustainability of European buildings at each stage of their life cycle.

The selection criteria for the economic aspects of the Sustainability dimension of the NEB paradigm mainly concerned a review of relevant frameworks and tools for greening the public sector focusing on the promotion of public investments in low emission assets and green economy, as well as on the implementation of decarbonisation activities. Other analyses referred to the social return of investment methodology and the economic spillover effects of the public investment. Indicators incorporating green financial tools, the financing of sustainable real estate investments, as well as the promotion and implementation of ESG factors and investments were analysed with reference to the greening of private and finance sector. Finally, studies on the degree of circularity of materials were investigated to elaborate relevant indicators fostering the circular economy within the built environment.

Following the review and analysis phase, the final selection and elaboration of relevant indicators, reflecting the sustainability priorities within the NEB initiative, came as a result of various efforts to (i) converge to a manageable number of commonly used indicators, (ii) identify consistently measurable indicators based on relevant standards, well established common practices and other consolidated methodologies, and (iii) ensure the development of quantitative indicators. As a result of this process, nine KPIs have been developed within the Sustainability dimension to evaluate the specific assessment targets at the different spatial scales, types, and main uses of a project.

The KPIs within the Sustainability dimension together with the associated indicators and indicator weights (w_S.i.j) are provided in Table 5 that also reports the KPI weights (w_S.i). The same table also presents the field of application and consideration of indicators according to the project classification based on scale, type, main use and relevance to cultural heritage.

Additional information on each KPI is provided in Sections 3.4-3.12, including the rationale, background, calculation method, and input data needed for the evaluation. The calculation method addresses the evaluation of indicator scores, KPI scores and KPI performance classes according to Sections 2.2.1 and 2.2.2.

Table 5. Key performance indicators (KPIs) within Sustainability.

¹ Although minimum KPI scores are not prescribed in the NEB self-assessment method, it is highly recommended that all KPIs attain the Acceptable performance class.

² Yes: Indicator applicable only to cultural heritage; No: Indicator non-applicable to cultural heritage; Not affected: Indicator applicable irrespective of cultural heritage.

³ Additional conditions apply: in the case of S.8, the S.8.2 indicator is included in the self-assessment of a project based on the condition that at least one of any potential private company involved in the project fulfils sustainability reporting obligations according to European Sustainability Reporting Standards. If this condition is not satisfied, S.8.2 is omitted and users utilise exclusively S.8.1 indicator.

Source: JRC.

The KPI performance class scores (PCS) assigned to all KPIs of the Sustainability dimension, as a function of the attained KPI performance class and KPI score (Section 2.2.3) are provided in Figure 10.

Figure 10. KPI performance class scores (PCS) in the Sustainability dimension.

Source: JRC.

The Sustainability (S) dimension score (Section 2.2.4) is evaluated according to Equation (5), as a weighted average of KPI performance class scores. All nine KPIs are always considered within the equation; however, the weight of each KPI (w_S,i) varies depending on the different combinations of project classification according to scale, type and main use (Table 5), so that the denominator of the equation always equals the unity.

(5)

The Sustainability dimension performance class is assessed considering the dimension score and the dimension thresholds, according to Figure 11.

Figure 11. Sustainability performance classes and thresholds.

Source: JRC.