FEBRUARY 2025

Rules for the declaration of environmental characteristics of construction products

Average scenarios outperform worst-case approaches

 

Glass for Europe welcomes the recent EU Construction Products Regulation (CPR) revision as a part of a multilegged process to make the EU construction products ecosystem fit for today’s and tomorrow’s needs, notably by enforcing environmental objectives on the construction products sector.

The implementation of the CPR needs to maintain consistent environmental declaration rules for construction products. Regarding building glass, Glass for Europe wishes to raise concerns about recent projects to overturn Life Cycle Assessment (LCA) and Environmental Product Declarations (EPDs) methodologies, which have been improved for over twenty years.

In particular, the “worst-case approach” envisaged by the Sub-group on Environmental Sustainability (SGEnv) raises significant concerns as it is not workable for the flat glass and glazing sector, characterised by a complex transformation value chain.

• Flat glass used for windows and façades is produced through a vast value chain (see Annex) involving multinationals, SMEs and microenterprises. A piece of glass is manufactured and transformed at different sites, companies, and countries before being installed into buildings.
• Single manufacturers can offer tens of thousands of product references whose upstream or downstream production steps are handled by various processors. Making LCAs in such a system implies using methodologies that give workable rules for manufacturers without creating disproportionate reporting and cost while enabling consumers to be well-informed.

Against this background, the “worst-case approach” would risk deteriorating the quality of environmental information currently shared within EPDs with consumers:

• Since thousands of actors apply similar processes when making flat glass products, operators need to differentiate products according to a limited number of parameters (e.g., performance) to maintain a reasonable number of product references and declarations.
• If environmental declarations must compile the worst impacts for each production process, overly pessimistic characteristics would be declared.
• To limit this issue, multiplying the number of declarations could enable the declaration of more representative data. Yet, it would also create new issues, such as red tape, costs, and error risks, without improving the relevance of the information given to consumers. Performing an LCA and publishing an EPD currently costs tens of thousands of euros per product group and requires specific knowledge, know-how, software, and databases. Each LCA/EPD is then verified by an independent verifier (further increasing costs and requiring time). Multiplying declarations would threaten companies that cannot afford these new compliance costs.

This paper details the difficulties of a worst-case approach and calls on policymakers to maintain existing EPD rules for declaring environmental essential characteristics with some adjustments.

 

1. Background

The current practice for assessing and declaring the environmental characteristics of construction products in Environmental Products Declarations (EPDs) is based on Life Cycle Assessment (LCA) standards (EN 15804) and other rules and procedures (c-PCR for glass in building, program operators’ instructions, etc.). This practice is the outcome of more than 20 years of continuous improvement.

EPDs aim to provide representative environmental impacts of a commercial reference or a group of similar commercial references put on a given market. To grasp the variability of production processes inherent to the flat glass industry, several rules are used to obtain representative results:

• Calculations are carried out using production data averaged over a long period, typically 1 year.
• When a product is manufactured in several sites, calculations are based on weighted average data from the various sites supplying the given market.
• When a product undergoes several transformation steps, calculations are based for each step on weighted average data from the sites potentially involved in each step.

This approach is sensible as it allows all the parameters influencing the environmental declarations of a product or a group of similar products on a given market to be considered without over or underestimation. Flat glass EPDs based on average scenario represent:

• A reliable and relevant source of information for the customers to make informed decisions based on environmental criteria.
• A proper and manageable solution for the manufacturers, with the possibility to demonstrate actual performance and progress of their products.

With this approach, stakeholders in the construction sector receive data that can be used to set and meet environmental thresholds in building regulation. Improvement in production infrastructure and marketing of products with reduced impact (e.g., lower embodied carbon values) are therefore incentivised.

This loop accelerates the journey toward a more sustainable building stock, and the new CPR could reinforce this system since it requires that environmental essential characteristics always be declared in the Declaration of Performance & Conformity (DoPC). Yet, recent discussions on the methodology for declaring environmental characteristics raise concerns.

The new CPR demands DoPC to be made per “product type”, i.e. “the abstract model of individual products, […] which exclude any variation with regard to performance or to the fulfilment of product requirements […] whilst identical products of different manufacturers belong to different product types.”[1]

The CPR Acquis – Sub-group on Environmental Sustainability (SGEnv) further states about environmental declarations: “Average values do not fit with the concept of product type because manufacturers cannot guarantee that the product sold is at least as good as the declared values.”[2] Such an interpretation of the CPR would jeopardise the current situation:

• It would require the declaration of worst-case performances for the environmental essential characteristics.
• To limit the related drawbacks, manufacturers would likely need to declare the environmental essential characteristics more granularly.

The implications of the above-mentioned effects are outlined in the following sections.

 

2. Worst-case environmental essential characteristics are inaccurate

The notion of the worst-case in LCA is not clearly standardised (even though already mentioned in EN 15941:2023). Introducing such a notion in regulation for the declaration of essential environmental characteristics raises a multitude of methodological questions that should not be overlooked (see examples of questions in Annex II). Beyond this methodological issue, declaring worst-case environmental characteristics would be detrimental to both customers and manufacturers.

• Impacts on customers

Customers would receive misleading information. As outlined earlier, the environmental aspects of production processes vary over place and time. Accurate worst-case data would need to account for the combination of successive worst situations, even if this scenario is purely theoretical.

With the worst-case approach, the data declared in DoPC would be much less representative of the actual environmental characteristics of products than the data currently provided in EPDs. Downgrading all products to the worst-case would mean losing what was gained with the current LCA approach, compared to using tabulated values for each material.

Finally, the relevance of selecting products or making LCAs for buildings based on DoPCs’ environmental data would be minimal since DoPCs would not provide information about the likely actual or average characteristics.

• Impacts on flat glass manufacturers

The worst-case approach would limit the ability of flat glass manufacturers and processors to demonstrate progress. The environmental declaration would no longer display past, current, and future measures that do not influence the worst-case production processes.

Manufacturers have been commonly investing in some measures that lead to efficient global improvements, but which do not entail direct actions to address plants/processes with the worst performance. One can also think of situations where local realities (country subsidies, energy mix/costs) permit improvements independently of whether they are on the worst impacts.

The worst-case approach would slow efficient progress, while the new CPR requirements attempt to do precisely the opposite.  Inefficient environmental measures that would only marginally improve the average impacts of a product type but would improve the worst impacts would even be rewarded.

 

3. The multiplication of product types is not a solution

To limit the above drawbacks, manufacturers and processors could define product types according to environmental characteristics. The number of product types would then be multiplied to isolate specific worst-case impacts. Considering the structure of the flat glass value chain (see Annex I), hundreds of thousands of different declarations would be created for building glass alone. This solution would have detrimental effects on manufacturers of basic glass, on glazing processors, on the window/curtain walling industry and on final customers.

• Impacts on customers within and after the flat glass value chain

Customers would start receiving unidentical declarations for seemingly identical products. This would make data management and readability more complex due to the variability of the shared data and the increased number of declarations.

Multiplying the number of product references would heavily complicate the stock management and purchasing procedures of customers. The exact upstream suppliers and production sites and their impacts are not always known far in advance. Planning the type of glass products received would, therefore, be very challenging. This would also limit the possibility of making building LCA calculations early in a construction project and optimising the building design.

• Impacts on flat glass manufacturers

For manufacturers, supply chain management would be complexified:

• Disruption in the continuity of operations due to customers asking for commercial references made in certain plants to ensure the predictability of environmental characteristic
• High number of LCA calculations to be made and managed.
• Verification work to increase, generating high demands for Notified Bodies.
• Confidentiality and competition compliance issues since declaring more precise production data (e.g. raw material and energy use) could display sensitive information (e.g. costs).
• Product management would be disrupted as manufacturers would need multiple different environmental performances, e.g. one from each site, for the same product (today, the same product reference can be produced in multiple plants);
• Marketing departments to deal with a vast and fast-evolving product portfolio and customer receiving a complex information.

The burdens related to the resourcing and costs of these issues would be particularly severe for small players, often customers and sellers of glazing products active downstream of and after the flat glass value chain.

 

4. Keep the current approach and improve it to fit new needs

Glass for Europe, therefore, calls on policymakers to keep the basis of the existing EPD rules to declare environmental essential characteristics in DoPC and maintain:

• The principle of data averaged over a long period (e.g. a year) when analysing a process’ impacts.
• The principle of weighted averaged data between plants along the value chain.

The following adjustments could be adopted to ensure that the actual environmental characteristics of a product are reasonably close to the average characteristics declared in the DoPC:

• Variation thresholds (of environmental characteristics) could be defined to group commercial references manufactured in several plants within the same product type. Consumers would then gain more certainty over the products’ specific impact.
• Manufacturers could monitor the weighted average data over time (via Factory Production Control), and industry-wide requirements could be defined to update declarations when certain deviations are reached.

Keeping the current approach with some improvements would have other positive side effects:

• During the 15-year transition time before the new CPR is fully implemented, the EPD system will remain a coexisting path to declaring environmental characteristics. Consistency between rules would permit competing products that do not have the same standard to display comparable data, avoiding market distortion. This would also avoid continually adjusting thresholds according to the gradual transition from an average declaration to a worst-case declaration.
• Since the declared value would be more precise (following the abovementioned proposals) and representative of the average, the DoPC would better co-relate to what manufacturers are required to declare under other legislation calculated according to well-established standards (e.g. CO₂ emissions)
• Avoiding the switch to a worst-case approach, in which there is no experience and no existing standards and rules, would reduce the risks of non-harmonised values, errors, and greenwashing. Although greenwashing is out of the CPR scope and is regulated by dedicated EU legislation, relying on a well-established and already successfully applied methodology (EN Standards, Product Category Rules for the sector) would support the general objective of making environmental data reliable.

[1] Regulation 2024/3110. Regulation (EU) No 2024/3110 of the European Parliament and of the Council of 27 November 2024 laying down harmonised rules for the marketing of construction products and repealing Regulation (EU) No 305/2011. http://data.europa.eu/eli/reg/2024/3110/oj

[2] CPR Acquis process – Sub-group on Environmental Sustainability. (2023, December 6). Milestone B: Assessment methods and declaration – Horizontal approach Task 1-6: Methodology for the assessment, declaration of performance, modularity, scenarios and reference service life

 

Annex I – Flat glass value chain

Flat glass used in buildings is manufactured in several steps through a global value chain. Raw materials and recycled flat glass are first melted in an oven that operates 24/7 for up to 20 years. The melted glass is either floated over a tin bath and annealed by controlled cooling in a long lehr or cast and rolled to give a pattern to one or both of its faces. During that process, a coating may be applied by pyrolysis. Once cooled, glass is cut, generally into standardised “jumbo” plates of 6m x 3.21m, the “basic glass”.

When out of the line, basic glass can already have hundreds of variations depending on the chosen combination of thickness, transparency (e.g. colour, clear, extra-clear), quality level (flatness quality, punctual quality, optical quality) and dimensions (from cut size to jumbo size and multiples), etc. Today, most basic glass sold in Europe is made by six manufacturers throughout the EU (~50 float lines in 2024), although some basic glass is imported.

The basic glass can be the finished product but is often dispatched to other plants to be processed. The following processes, although not all compatible with one another, can be applied to the same basic glass in varying orders and are subject to EU standards:

• Coating (solar control, low emissivity)
• Laminating
• Mirror coating
• Painting
• Sandblasting
• Acid etching
• Prestressing
• Applying a polymeric film
• Curving
• Assembly in Insulated Glass Units (IGU), see e.g. Figure 1
• Assembly in Vacuum Insulated Glass (VIG)

Figure 1: Sectional view of an Insulated Glass Unit (IGU) showing the variety of intermediate products that compose a relatively standard triple-glazing product used in modern buildings

Processing works are handled much more granularly than the melting process. In the EU alone, thousands of companies, often SMEs, are involved in one or more processes, sometimes on several sites.

Once processed, the glass product can be installed in buildings or mounted in other construction products, which are, in turn, installed in buildings. This includes, e.g.:

• Curtain wall
• Window
• Building Integrated Photovoltaics (BIPV)
• Balustrade
• Floor
• Skylight
• Door
• Glass column
• Glass beam
• Shower enclosure

To comply with the EU Construction Products Regulation (CPR), manufacturers fulfil the requirements of the respective harmonised standards and CE-mark glass products before putting them on the market with a declaration listing various product performances and characteristics.

Basic glass, finished glass products, and construction products that use glass products as components, e.g., windows, can be CE-marked and have dedicated product declarations.

 

Annex II – Questions on declaring worst-case LCA results

A worst-case approach applied to the declaration of environmental essential characteristics for flat glass products raises numerous questions. Some of these questions are gathered in this annex (non-exhaustive list). These questions can be separated into two categories: how the worst-case would be defined and how the environmental essential characteristics would be declared.

Defining “worst-case”

• How do we account for the variability over time for a commercial reference produced in one plant (supplied raw materials, availability of recycled materials, yields, technical issues, maintenance)?
• How do we account for the variability of a commercial reference produced in several plants?
• How do we account for variations in transportation flows between plants in the supply chain? For instance, how can we account for a basic glass temporarily produced in another plant (e.g., due to the cold-repair of the oven, which takes several months to make) and still be processed according to what was declared when making the LCA?
• How do we account for the variability of the value chain for a commercial reference undergoing several manufacturing steps that can be all performed in multiple plants?

LCA calculation method and rules for declaration of characteristics

• For a given environmental characteristic (one LCA indicator), should one consider the worst situation for all the parameters (data) of the LCA model simultaneously, even if this situation is unrealistic?
• When declaring the whole set of environmental characteristics (all LCA indicators), should one mix the worst result obtained for each characteristic (each LCA indicator) based on different scenarios, even if it leads to the declaration of uncorrelated and, thus, inconsistent LCA results?
• If one only considers realistic scenarios (as it is done for structural safety rules, see Eurocodes), which worst environmental characteristic (LCA indicator) would need to be prioritised to define the worst-case product and subsequent characteristics? For instance, if product A has a better Global Warming Potential but worse Ozone Depletion than product A’ (same product type), which characteristics should be declared in the DoPC, the ones of product A, A’, a mix of the two?
• How do we demonstrate that all products within a product type have better characteristics than those declared values? Which calculation procedure? What tolerances? Which temporal granularity for the data collection period?
• For all points above, how can we ensure that all manufacturers use a consistent approach?