Beyond the Scrap Heap: Data-Driven Strategies for Sandwich Panel Reuse

This article explores the findings of a mixed-methods study conducted in the Iberian Peninsula. By combining Urban Metabolism (the quantitative flow of materials through a city) with a Stakeholder Market Survey and in-depth interviews, we aim to identify why circularity remains stalled in the industrial building sector and how digital tools might—or might not—bridge the gap.

1. Urban Metabolism: The 2030 Intervention Window

The concept of Urban Metabolism treats the built environment as a "living" stock of materials. Between 2005 and 2015, Portugal, Spain, and France saw a massive expansion of logistics and industrial hubs, resulting in a stock of 240 million m2 of steel-faced sandwich panels.

As these buildings reach a 20-to-25-year renovation cycle, a "wave" of removals is expected between 2025 and 2030. This timing is critical. Currently, these panels are treated as waste to be downcycled into scrap steel. However, since many are removed due to functional building changes rather than technical degradation, they represent a significant "anthropogenic reservoir" of functional components.

Estimated area of sandwich panels (installed between 2005 and 2015) in Portugal, France, and Spain, based on Eurostat data.

2. Qualitative Realities: Insights from 5 Key Interviews

To contextualize the data, we conducted semi-structured interviews with five key actors: building owners, demolition subcontractors, and designers. These conversations revealed "latent" drivers that surveys often miss:

• The Fragility of Logistics: Demolition experts noted that "delicate deconstruction" is rarely priced into contracts. Without a clear buyer, the cost of careful removal (6–9 €/m2) is seen as a financial loss compared to rapid demolition.

• The Insurance Void: Designers expressed that even with perfect data, the lack of a standardized "conformity assessment" for fire safety makes specifying reused panels a professional risk they are unwilling to take.

• Cultural Resistance: Interviews highlighted an organizational "risk culture" where new is always synonymous with "safe," regardless of what the data says about residual material performance.

3. Scenario 1: New Warehouse Construction

We presented three procurement tiers for a new build to 11 stakeholders managing projects over 15,000 m2:

• Option A (New - 40 €/m2): The standard choice for 70% of respondents.

• Option B (Certified Reuse - 30 €/m2): Used panels with damage detection and lifetime estimates.

• Option C (Ad-hoc Reuse - 20 €/m2): Uncertified panels.

The Verdict: While Option B is the most sustainable according to Life Cycle Assessment (LCA) data, it lacks the legal framework to compete with Option A. Option C was largely dismissed, proving that cost savings alone cannot create a secondary market.

Scenario 1 options for new warehouse: a) Life cycle cost assessment and b) Elemental Life cycle assessment. Option A - new panel (40 €/m²), Option B - repaired used panel that includes damage detection and life-expectancy estimates (30 €/m²) and Option C: reused panel without certification (20 €/m²).

4. Scenario 2: Existing Warehouse Interventions

When managing an aging asset, four strategies were evaluated.

• Option A: Full replacement (40 €/m2).

• Option B: Targeted repair and postponed replacement (26 €/m2).

• Option C: Replacement with certified reused panels (33 €/m2).

• Option D: Ad-hoc Repair (15 €/m2): Localized, uncertified patching.

The Conclusion: Option D was highly rejected. Stakeholders viewed it as a "band-aid" solution. The lack of technical certification makes it unfeasible for industrial insurance and safety standards, as it offers zero predictability regarding the building's future performance or resale value.

Scenario 2 options for existing warehouse: a) Life cycle cost assessment and b) Elemental Life cycle assessment. Option A - full replacement (40 €/m²), Option B - repair used panel and postpone new sandwich panel replacement (26 €/m²), Option C - replace with certified reused panels (33 €/m²) and Option D - ad-hoc repair (15 €/m²).

5. Financial Drivers: LCC and LCA Realities

• CAPEX vs. OPEX: New panels (High CAPEX) are the safe route, but digital monitoring allows for a shift toward optimized OPEX. By repairing instead of replacing, owners can extend service life, though this requires high-quality data to justify the investment.

• The Conflict: LCA data suggests that reuse is the only way to meet aggressive carbon reduction targets. However, the LCC of "delicate deconstruction" often makes the resale price of a reused panel too close to the price of a new one to justify the perceived risk.

6. The Material Passport: A Partial Solution

A BIM-integrated Material Passport aims to solve the Information Gap by recording fire ratings, core composition, and corrosion levels.

Example of the layout of a PDF report generated from an IFC material passport.

Critique of the Passport Approach: The Material Passport is not a "silver bullet". Significant hurdles remain:

• Liability Mismatch: A passport provides data, but not a legal warranty. If a reused panel fails, the passport-holder is not necessarily the liable party, leaving a legal vacuum.

• Logistical Friction: Digital data does not solve the physical problem of storing bulky panels. The "timing mismatch" between supply (demolition) and demand (new construction) remains a major hurdle.

• Cost of Data: The labor required for high-tech inspection (drones/sensors) can erode the price advantage of reuse, potentially making the circular option more expensive than virgin material.

In the circular economy, a panel without data is just scrap — but a panel with a passport is a proven asset that de-risks the future of construction.