METHODO­LOGY

This catalogue presents the climate impact of 26 best-practice cases from the Nordic countries and Estonia. It is meant an inspiration and a collection of examples of measures taken to reduce the climate impact. Cases are modelled with varying Life Cycle Assessment (LCA) methods and tools related to the participating countries and project context. Therefore, result comparison across cases is often not possible. Even at country level, method variation may occur due to varying regulatory requirements and certification systems. Also, methods evolve over time, not at least regarding a more complete and mandatory regime for carbon regulation today compared to a historically dominating voluntary certification schemes. As the Nordic countries are implementing mandatory declarations and limit values, a greater degree of harmonisation is expected in the future. A thorough analysis and comparison of methodological differences in the Nordic countries is available in previously published reports.

Erlandsson, M., Görman, F., Thrysin, Å., Häkkinen, T., Eckerberg, K., Pesu, J., & Dalborg, M. (2024). Nordic view on data needs and scenario settings for full life cycle building environmental assessment. Nordic Innovation. https://pub.norden.org/us2024-428

To enhance transparency and facilitate result interpretation, Table 1 provides an overview of the choices related to selected influential methodological aspects. These aspects include area definition, included modules, included elements, the Global Warming Potential (GWP) indicator used, emissions data sources for generic materials, decarbonisation scenarios (for energy and materials) and exported energy. Like most countries, the Nordics use a 50-year reference study period. A brief explanation of major methodological differences is provided below.

Area definition: This choice of area definition significantly influences the reported outcomes of climate impact assessments for the cases. For instance, calculating climate impact per ­­gross floor area (GFA) yields different results than assessments based on heated floor area (HFA) or net heated area. Currently, there is a lack of standardisation in the reference units and definitions employed across Nordic nations

Balouktsi, M., Kanafani, K., Francart, N., Langkjær, N., Ryberg, M. (2024): Decarbonisation Of The Building Stock. Nordic Innovation. https://pub.norden.org/us2024-438

. This variability complicates the ability to compare results across countries.

Life cycle stages: Buildings go through various stages throughout their life cycle, which include the product stage, the construction process, the use stage, and the end-of-life stage. The EN 15978 standard provides a modular framework for defining these stages and serves as a reference for current regulations and certifications in the Nordic countries. This standard is also used in the presentation of results in the following section. Carbon emissions from the product stage (A1-A3) and the construction stage (A4-A5) are often combined and referred to as upfront embodied carbon emissions, as they occur before the building is commissioned. Scenario-based embodied carbon emissions include emissions from use (B1), maintenance (B2), repair (B3), product replacements (B4), and refurbishments (B5) that take place during the building's use phase, along with end-of-life processes (C1-C4). Operational emissions are related to energy consumption (B6) and water consumption (B7) during the building’s reference study period. Differences in system boundaries in the case  assessments are a significant factor that limits the comparability of the presented values. The results are displayed per life cycle module wherever possible to improve transparency.

Building components: System boundaries in best practice cases also vary in this aspect. The biggest discrepancies lie in the partial or full inclusion or exclusion of site preparation, building services, external works and furnishing. Even if two countries may have identical scopes, the included level of detail per component may differ. Another aspect is that standard values may be used for certain components such as building services in some cases, while other cases may have project-specific detailed calculated values. This is not indicated in the results other than the broader included scope of components.

GWP indicator: The Nordic countries currently use different scopes of the Global Warming Potential (GWP) indicator. For instance, Finland and Denmark employ a comprehensive measure called GWP-total, which includes biogenic emissions as well as emissions from land use and fossil fuels. In contrast, Sweden and Norway focus solely on emissions from land use and fossil fuels, using the indicator GWP-GHG, while omitting the biogenic part.  Due to these varying indicators, it is not possible to make direct module-by-module comparisons of carbon calculations across countries; any interpretations should be understood in context.

Climate impact data: In best practice cases, climate impact calculations should ideally use environmental data from product-specific Environmental Product Declarations (EPDs) and EPDs from national industry associations as much as possible

Balouktsi, M., Kanafani, K., Francart, N., Langkjær, N., Ryberg, M. (2024): Decarbonisation Of The Building Stock. Nordic Innovation. https://pub.norden.org/us2024-438

. Using data that is specific to the industry and product minimises uncertainties in climate impact results compared to generic data. Generic environmental data across Nordic countries are commonly representing a conservative, higher level of impacts. However, specific information on the usage of EPDs has not been collected. Additionally, since conservative factor approaches and other aspects of developing generic data vary among Nordic countries, results may be difficult to compare even when the same scope is applied.

Decarbonisation scenarios: One of the most significant variations in calculation methods involves the choice between using current emissions and future emissions from energy use, that account for planned renewable conversion of production for electricity, district heating, and gas. This is particularly relevant for calculating operational energy (B6). Several used methods have scenarios for gradual decarbonisation of the energy supply in this module. However, even if two methods from different countries include such decarbonisation scenarios, they may still be incomparable due to differing national preconditions such as policy, data and methodologies. Regarding decarbonisation scenarios for materials used in future processes, such as replacements (B4), only the FutureBuilt scheme currently incorporate these scenarios.

Exported energy: According to the EU Building Directive (EPBD), “exported energy” refers to the portion of renewable energy generated on a building site that is sent to the energy grid, rather than being utilised on-site for purposes such as self-consumption or electric vehicle charging. The rules governing how renewable energy generated on-site is calculated and distributed for different uses are expected to be a significant focus in the revision of the EPBD as it a critical factor of comparability. However, current approaches vary across different certification systems and regulations. The treatment of exported energy involves not only decisions on how energy savings are allocated, but also considerations of the supply chain impacts, which include the embodied impacts of renewable energy systems. 

Table 1: Overview of main methodological aspects behind the sourced climate impact values of the best practice cases. Note: EDW: External doors and windows; IDW: Internal doors and windows; EF: External finishes; IF: Internal finishes; BS: Building services; Fixed furniture: FF; Specialist groundworks and piling: SG.