Within the framework of the Energy Performance of Buildings Directive (EPBD), a reference service life period of 50 years is used to assess a building’s environmental and energy impact. The aim is to harmonise calculations across Europe.

However, applying this 50-year period to specific construction products, such as thermal insulation, raises several technical and methodological questions.

RSL and ESL: straightforward concepts, challenging application

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The Reference Service Life (RSL) corresponds to the expected lifespan of a product, component or system under defined service conditions. It serves as a baseline reference and is not intended to predict actual performance in all situations.

The Estimated Service Life (ESL), on the other hand, aims to reflect actual service conditions and can be calculated as follows:

ESL=RSL×A×B×C×…

Factors A, B, C… include design quality, material quality, workmanship, exposure, maintenance, and use.

Although the concept is well established, notably through the ISO 15686 series, its application remains complex. For example, insulation installed in Munich will not be exposed to the same conditions as in Brussels. Yet, the impact of this difference on ESL calculation is not always clear, and its application varies across assessments.

50 years for thermal insulation: technical reality or convention?

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Compared to other building elements such as interior finishes, roofing, or windows, which often have shorter RSLs, thermal insulation is typically associated with a reference service life of 50 years.

But does this value correspond to proven durability under all conditions, or a conventional reference, aligned with the EPBD study period?

In practice, insulation is rarely replaced. It is often retained and supplemented with new layers during renovations. This demonstrates a long service life under favourable conditions, but raises the question: should we always assume no replacement over 50 years, or does this assumption oversimplify actual practices?

Regulatory framework: towards European alignment

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At the EU level, RSL is becoming a key characteristic for assessing environmental performance, with links between ESPR → CPR → EPBD.

Within the Construction Products Regulation (CPR), RSL appears as the default value in the Environmental Product Performance Declaration (DoPC).

The EPBD recommends using data from the Construction Framework (CF) developed under the CPR.

However:

• these data are not yet complete,
• Consistency between products and EPD operators is still under development.

This creates uncertainties, especially when different EPDs use different RSL assumptions for similar products.

c-PCRs: opportunities and limitations

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Future Construction Product Category Rules (c-PCRs) for producing Environmental Product Declarations (EPDs) could allow RSLs greater than 50 years, if justified by tests, specific product evidence, or clearly defined essential characteristics.

However, several questions remain open:

• Which tests can justify an extended RSL?
• How can ageing mechanisms be taken into account?
• How can realistic and harmonised service conditions be defined?

The draft Standardisation Requests (SReq) highlight these challenges and call for clear technical and functional conditions, transparent links between RSL and essential performance, and explicit rules for ageing.

While the 50-year reference period is used to harmonise calculations, some Member States define longer building lifespans, sometimes up to 100 years.

This raises methodological questions: should the RSL of products always follow the reference period? How should highly durable or uncertain products be treated in extended assessments? Answers are not yet fully established.

Reference service life is not a prediction

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RSL should be seen as a working basis, not as an exact prediction.

• ESL remains the responsibility of the specifier.
• RSL provides a common starting point for environmental declarations.

For thermal insulation:

• The 50-year RSL is generally reasonable,
• It does not guarantee the exact service life and does not set a strict technical limit.

It reflects the current state of harmonisation, available data, and the regulatory framework, while leaving room for adjustments as c-PCRs evolve and field experience accumulates.