Summary and recommendations

Introduction and targets

There is a clear need to harmonise the environmental assessment of buildings. Both the EU and national governments are planning to regulate, if not already regulating, buildings based on the amount of life cycle emissions. According to the new Energy Performance of Buildings Directive (EPBD), it will be mandatory to report a so called life-cycle GWP (Global Warming Potential) indicator result for all new buildings. This includes both greenhouse gas (GHG) emissions embedded into building materials and emission caused in the construction stage, use of the buildings, and end-of-life. This life cycle assessment (LCA) of buildings requires a great deal of data, assumptions, and calculations. Comparable results can only be achieved if the data and the calculation methods are based on the same methodology and scenario settings. The need to standardise or agree on principles is further emphasised by the number of stakeholders related to buildings' design, construction, and operation.

This report is part of the Nordic efforts to harmonise full life cycle environmental assessment. All views, interpretations, and recommendations are made by the authors and represent no official statements.

Main targets for the report are:

Establish a common view and understanding of the GWP data for all kinds of resources that are used by the building during its life cycle and the LCA methodology settings needed. LCA methodology settings are preferably based on the existing and applied standards and the current praxis already implemented, and thereby cost-effective.
Give recommendations on scenario settings and calculations rules based on both expertise and experience.
Study some of the previously identified areas of missing or limited information.

It is important to understand the standards and LCA practices, and highlight issues that have not been considered thus far in the creation of national rules or standards for the assessment of buildings. Since 2021, there has been national building GWP databases and LCA calculation methods in some Nordic countries. The industry cooperation and feedback has been an important part of improving the databases and methods.

The standardisation and regulation development are ongoing, and all statements in regard to the future are predictions and/or recommendations. Most recommendations are assuming strong EU regulations based on the standardisation process. Following all recommendations, even if a decision would be made today, will require considerable efforts and take time.

This report makes recommendations on future calculations needed for the EPBD life-cycle GWP indicator for buildings. A tiered approach is suggested when a recommendation is worked out, where the first choice is to use the European common method and only when the necessary national specifications or scenario settings or additions are used. Besides referring to the already implemented European standards, the recommendations also refer to the EU work that is already made, e.g. energy decarbonisation scenarios. This approach supports a common agreement of the recommendations worked out, as well as a cost-effective implementation of the LCA.

Due to the needs of planned regulation, some potential areas to be part of a building climate declaration, as well as open questions about those topics, have been selected to be studied further within this project. The following potential topics are handled:

Inclusion of vegetation on the building plot
The potential to assess an GWP indicator for existing buildings (old buildings)
How can sustainable forests be defined and hereby, for instance, potentially in the future, be accounted for a biogenic carbon sink when there are parts of long-lived construction products like sawn timber?

Global Warming Potential (GWP) indicators

The main indicator for climate LCA databases is GWP. There is also a consensus from the standardisation work, as well as EU initiatives that the GWP indicator shall be divided in:

GWP total: the sum of GWP fossil, GWP biogenic, and GWP land use and land use change (luluc)
GWP fossil: the sum of all greenhouse gas emissions from fossil sources
GWP biogenic: emission of all greenhouse gases and biogenic carbon stored in the product and its packaging materials
GWP luluc: the emission from potential land use and land use change

The use of the GWP total indicator is unproblematic when it includes all information modules from A to C. However, the GWP total as a GWP indicator restricts the comparison between individual modules, as the uptake and emission of biogenic carbon occurs in different modules and only balanced out over the full life cycle to zero. The solution for this is to apply a complementary GWP indicator here, referred to as GWP-GHG (or sometimes named GWP-IOBC). This GWP-GHG indicator can be calculated with the existing mandatory information reported in an EPD (Environmental Product Declarations). This indicator accounts for all greenhouse gases except the biogenic carbon uptake in the product or its packaging and emissions in the end of life. Thereby, the LCA result is comparable information module by module. This is of special interest when limit values do not cover the full life cycle. This is, for instance, asked for in Sweden, where a limit value is also asked for the construction stage (A1-A5). It should be noted that the life cycle GWP indicator, according to the Taxonomy and EPBD directive, is based on the summed impact from A to C, which is why there is no difference in the result whether the GWP total or GWP-GHG was used when the full life cycle is assessed.

A harmonisation of GWP indicator use is needed and must be found on the information given in an EPD. The GWP total shall be used when the impact is summed from A to C. If any nation introduces an additional limit value for a single stage (like A1-A5), the use of GWP-GHG is recommended.

Data

GWP data for generic databases for construction products is based on publicly available information, such as EPDs. The data is still far from perfect as the quality of generic data varies, especially due to the lack of EPDs in some service and product areas. To support the creation and use of EPDs, conservative factors (+20 to +25%) have commonly been applied to cradle-to-gate (A1-3) values. When it is feasible to require specific EPD data for construction products supported by European Commission law, it is possible to phase out the conservative factor in this kind of generic databases.

The construction market is largely domestic for many construction materials that significantly contribute to the GWP. Although common approaches between countries can be applied for the collection of source data, at least the domestic high-volume products should be handled nationally based on national EPDs, and the market share should be taken into consideration if possible when generic data is defined.

Scenario setting

A climate declaration according to the EPBD life-cycle GWP indicator covers the future and thus the scenario settings for modules B and C. These scenario settings need to be harmonised on a common basis to maintain comparability and consistent results for all parties. The recommendation is to define the scenario settings as representative as possible, based on a stepwise approach. This approach should cover geographical representativeness, technology representativeness, time representativeness, use of specific data, and transparency in reporting. Where a simplification is possible, a European common average approach can be used as a default starting point. Nordic or national scenarios can then be created based on the same methodology approach as applied in the European scenario setting. It is further recommended that all scenarios are based either on the parametrisation or otherwise open reporting of the data sources and calculations, rather than a fixed calculated GWP result.

Decarbonisation scenarios are recommended for B and C modules that describes the improved climate impact in future. There are high resolution scenarios developed by the European Commission based on national information and political decisions, which can therefore be used as a common source all over Europe. Also, national scenarios have been created by the national regulators. For simplicity, one decarbonisation scenario is presented for modules B1.2-B5, B7, and C1-C4, and another scenario for B6. The scenario shall not be applied for the carbonisation of concrete and build in carbon, such as biogenic carbon or carbon stored in, e.g. plastic that is released in C3/C4. The suggested decarbonisation scenario for the first above-mentioned information modules is the EU Prime scenario called “Total GHG emissions, excl. international excl. LULUCF”. The EU Reference Scenario 2020 is the baseline scenario to assess options informing the policy initiatives in the European Green Deal package adopted by the European Commission. The recommended scenario for B6 is a simplified approach to the EU Prime residential scenario. If a national/local energy scenario(s) exists, these can be used and reported as additional information to maintain comparability across countries and transparency when national regulated scenarios are developed. The energy mix used as the default is the national grid mix.

Recommendations by module

Table 1 below summarises the recommendations for each LCA module. It also adds information on what could be developed in the EPD to support calculations on the building level. More in-depth discussions and recommendations can be found in later chapters.

Module	Recommendation
A1-A3: Product phase	In a building permit: Generic national representative GWP data on at least high-volume construction products must be advised (typically 80% of GWP-GHG A1-5) and publicly available for free and collected in a GWP database. As built: Generic data may be replaced by specific EPDs according to EN 15804 if the product is bought.
A4: Transport	In a building permit: Parametrisation on transport combined with a default transport distance per generic building product valid for the European or national level. As built: Part or all of the generic parameters advised by an authority in the transport scenario may be replaced with specific data if verification exists. EPD support: In an EPD, it is possible to define commonly applicable mix-scenarios for A4 for different European regions and/or countries.
A5 Construction process, Energy (A5.2)	In a building permit: Ready-made default GWP data, i.e. template data, based on different building types are recommended based on a European or national representativeness. As built: measured data and if this is not measured, advised generic data as listed above must be used. EPD support/building permit: It is recommended to develop a common European parametrisation scenario. This default scenario is used for all construction products if the so-called complementary product category rules (cPCR) that are developed for a specific construction product do not develop a more representative parametrisation scenario.
A5 Construction process, Waste (A5.3)	In a building permit: A generic waste factor from the installation process is given per construction product based on a European or national representativeness. The simplified Nordic data to be used is presented here. As built: On-site measured waste generated data may be used if it can be proofed, and if not possible, it is acceptable to use the advised generic data as listed above. EPD support/simplified approach: It is recommended to define a common European waste factor per cPCR developed.
Stage B, C and potentially D	It is recommended to use a decarbonation scenario for scenario settings, These GWP figures can be generated by a simplified so-called three-point-method scenario approach. As the minimum, one scenario shall be applied that should be a WEM or WAM²⁴ scenario where WEM is the preferred choice.
B1 Use, Carbonation from concrete (B1.1)	A simplified option: A Nordic default figure for all concrete products is recommended and presented here. More specific option: A specific calculation can be made, and it must follow EN 16757 and found on material characteristics for the specific products used. EPD support/simplified approach: It is recommended to define a common European template approach with the most frequent intended use alternatives to be included in the cPCR when it is relevant.
B1 Use, Emissions of refrigerants (B1.2 )	A simplified option: A Nordic default figure for all emissions of refrigerants per year and the useful area heated and/or cooled with compressors that use refrigerants is recommended. More specific option: How a more specific value should be calculated needs to be decided in the delegated act or by the national legislation. EPD support: It is recommended to define a common European template approach on leaching with the most frequent intended use alternatives to be included in the cPCR when it is relevant.
B2 Maintenance	GWP data: Data used for A1-A5 can be used for B2-B5 with a decarbonisation scenario, a number of replacements based on the decimal number approach of the estimated service life. Reference study period (RSP): It is suggested that a RSP of 50 years is used for all architypes and that it reflects the time span when a building needs to be rebuilt and modernised. Calculation method: prEN 15987, the decimal number approach is recommended. Estimated service life (ESL): It is recommended that the delegated act includes a European default set of the ESL. These ESLs can be replaced by a generic nationally-defined ESL. These data can be replaced by the EPD data if it is based on a cPCR that includes generic ESL data and/or instructions for a product-specific specified ESL.
B3 Repair	as for B2, where information on the repair can typically be found in statistic information.
B4 Replacement	as for B2
B5 Refurbishment	as for B2, where it is recommended that the B5 refurbishment is more strictly defined to cover the combined upholding exchange activities and process that covers more than one building element.
B6 Operational energy use	A simplified option: Approach A in prEN 15978, as defined for B6, is combined with the energy use data as defined in the national implementation of EPBD. It is recommended to use a decarbonisation scenario based on EU Prime. More specific option: A national scenario can be used if advised by the authority and then reported as additional information. The energy mix used as the default is the national grid mix.
B7 Operational water use	It is recommended that European common figures as part of the delegated act can be used if national data does not exist. EPD support: The same parameterisation can be used in the EPD and then directly used for input on the building level. These GWP values can be replaced by EPD data related to the actual water supply or wastewater treatment, or other specific data in line with the EN 15804 methodology. The simplified Nordic data to be used is presented here.
C1 Deconstruction, demolition	A European generic parametrisation is recommended and the corresponding data to be used is presented here. EPD support: The same parameterisation can be used in the EPD and then directly used for input on the building level.
C2 Transport	Similar to A2 in a building permit, but where a European (one figure) average distance is 50 km, or different distances per material category, can be overruled by national additions or potentially specific distances. EPD support: In an EPD, it is possible to publish several scenarios for C2 for different European regions and/or countries.
C3 Waste processing and C4 Disposal	It is recommended that C3/C4 is based on parameterisation that can be used to develop on a 100%-scenario of different waste treatment scenarios scenarios that are listed in this report. Then the ready-made 100% scenario can be published, representing European averages in the EPBD delegated act. EPD support: The 100% scenario data can be supplied by a EPD that then must include the relevant 100% reported separately and defined in the PCR.
D Re-use, recovery, recycling potential	Not included in the EPBD life-cycle GWP. Optional to add on a national level.

Table 1 Recommendations by module

GWP declaration supervision

The trust of the certificate must be supported by a supervision (auditing) process. The importance of establishing a cost-effective and sufficient supervision process is something that is not fully developed for today's building climate declaration. It is notable that the need for a supervision process will increase when the limit values are launched to support a fair comparison and free competition. As part of the supervision, in order to digitally validate numerical values from building systems parts, it is necessary to introduce a classification system of grouping a ‘building element type’. Then, to create a key performance indicator (KPI) per the ‘construction element type’ that can be used to evaluate if the specific reported value for a building element type can be compared to the statistic normal value, a common reference unit is needed.

In the long run, it is recommended that a free-to-use European classification system based on the standard IEC/ISO 81346-2 Classification of objects and codes for classes should be established in lieu of different national classification systems. It should be recognised that further developments would be needed since the current IEC/ISO 81346 does not include a granularity for the ‘construction element type’, where the materials used in a construction element are typically accounted for. Such granularity is essential and is needed to make a digitalised cost-effective supervision possible, since the amount of construction product data that is part of the integrated life-cycle GWP supervision may cover several tens of thousands of data rows.

Data for vegetation

As indicated in Table 1, there is still quite a lot of harmonisation potential, but there are some knowledge gaps even in Product phase (A1-3). One of the more difficult questions has been the calculation of the effect of vegetation, mainly trees. There are few relevant LCA results on vegetation and correspondingly, no data in generic databases. Although most of the current or planned regulation do not require an assessment of the building site and its vegetation, there is a clear market demand to understand the climate impact of vegetation in addition to the building itself. When vegetation is reported as a complement to the mandatory part of the EPBD life-cycle GWP indicator, this kind of information also needs to be produced in a harmonised manner. This information from vegetation can be regarded as an extension of the mandatory information that shall be part of other biogenic sink effects, as asked by the EPBD directive (see Annex V), related to the physical building itself, referred to as: “information on carbon removals associated to the temporary storage of carbon in or on buildings”.

The resulting LCA data for trees shows that over a 50-year period, the amount of carbon sequestered by trees is significantly higher than greenhouse gas (GHG) emissions from the planting, maintenance, or removal of a tree. The highest carbon sink is achieved when the existing trees are not cut and remain in the area during a construction phase. Although the removal of trees results in the highest GHG emissions, this can be partly compensated by planting new trees and creating a new sink.

More in-depth discussion and results on the data for vegetation can be found in Annex 4.

Sustainable forestry

The assessment of biogenic materials in construction products has been another frequently raised issue. This work deals with sustainable forests as it is the major source for renewable materials stored in a building. It has been agreed in the LCA methodology currently used (EN15805, EN 15978) that biogenic carbon always will be zero over the life cycle A to C when the product comes from a sustainably managed forest. Since the term sustainable forestry has not been well-defined in these standards, the project arranged for an expert workshop to discuss sustainable forestry in relation to building LCAs. Wood-based products from sustainable forests are also a prerequisite for being considered a potential source for the EPBD declaration of mandatory information on carbon removal associated with the temporary storage of carbon in or on buildings (see Annex V).

A report on the considerations for defining sustainable forestry in LCAs for biogenic carbon can be found in Annex 5.

Data for old buildings

Current construction processes and tools enable good knowledge regarding the material composition of new buildings, but there is little data on the material content of existing buildings here referred to as old buildings. Our building stock volume, which grows through new construction annually, is very limited. According to Eurostat, 85% of buildings in the EU were built before 2000 and it is estimated that 85-95% of the buildings that exist today will still be standing in 2050. The existing building stock and, e.g. transformation, utilisation, and renovations are upcoming focus areas in regulation.

Dealing with the existing building stock in climate regulation is an open question in all Nordic countries, but a discussion has been opened on both the methods and availability of data. If, for example, a renovation would require a climate declaration for the building permit, the deconstruction phase would also need to be assessed to evaluate the deconstruction, transport, waste management, and disposal of the to-be-removed material. However, such existing materials are currently regarded as sank costs in LCAs, and only the new construction materials added are accounted for when the building is refurbished or deeply renovated. The EPBD requires a climate declaration on the same format as for new buildings for renovations that achieve A+ (no other renovations require a climate declaration).

It was proven possible to use archetypes to estimate the amount of main materials in different typical building structures for old buildings. Because such information is very generic, the use of building-specific data is recommended where possible. The existence of generic information opens possibilities for the early planning and rough evaluation of overall material flows.

A report on the data for old buildings can be found in Annex 6.

Databases and interoperability

Most Nordic countries already have a generic GWP database for construction products in operation or refer to others' domestic databases that shall be used when generic data are used. The scope of databases typically follows the current or planned scope of climate declaration. All databases include cradle-to-gate data for construction products, energy wares, and any other resource to be used in module A1-3. The availability of data for other modules and indicators varies.

These national databases are used widely and their GWP data are integrated into a wide range of tools. All databases are free to use and feature simple interoperability based on machine-readable files. However, common formats, naming, and classifications have not been defined to fully facilitate the interoperability; and currently, the databases mostly interface with tools for calculating the GWP impact.

The GWP databases adequately support the needs for current calculation methods, but some development is required to follow the forthcoming regulation and interoperability needs. The adoption of LCA data into BIM requires machine-readable EPDs and generic data preferably in a common format. The most promising and recommended way to achieve this is through the work on product so-called data templates, which will also be used for other aspects of the regulated construction product performance declaration. Another requirement, in practice, is a common classification system of building parts. All classification systems for the built environment have their strength and weaknesses, based on their purpose. It is recommended to base the common classification system on IEC/ISO 81346, which is the only system designed for the life-cycle stable classification and identification of digital objects.

Scope and regulation

The scope of building LCA should be defined according to regulatory targets and their priorities, but it is not easy to decide what is good enough. While the recommendations of this report set the bar high on accuracy and completeness, it tries to take into account what is also doable in practice.

The current plans and related actions of Nordic authorities are in line with envisioned future EU regulations and the recommendations of this report. The situation today, however, is quite different across the countries. The scope of the declared modules, as well as the included building elements, are not harmonised, and neither is the area regarding how much of the services and processes should be product-based and how much on a building level (e.g. emissions /m² for a given architype).

Data and databases are not the driving force behind deciding the scope of regulation or calculation method, but decisions on regulation directly affect the cost and effort needed to create and maintain generic data. Overall, it would be interesting to analyse the cost and potential impact of different scopes and regulatory options. A complete life cycle assessment is a multi-faceted and complicated method – hopefully, this report can answer some questions, but it is good to keep in mind that standardisation and regulatory work continue, and both questions and answers may change in time.