Scientific Evaluation of Local and Traditional Building Materials: Sustainability, Performance, and Limits
Introduction
Historically, local and traditional building materials have been shaped by the climatic data and natural resources of their geography, offering unique engineering solutions (Ashurst & Ashurst, 2013).
Today, the climate crisis and carbon emission targets direct the construction sector toward low-energy and biosphere-compatible materials (Walker, 2007). Lime, stone, and organic binders are not only cultural heritage but also provide scientific data with high potential within the framework of modern sustainability criteria (LCA – Life Cycle Assessment) (García-Herrera et al., 2020).
1. Lime: The Chemical Foundation of Breathing Buildings
Due to low firing temperatures (~900°C), lime has a significantly lower “embodied energy” compared to cement (Minke, 2012).
Advantages:
- Low carbon footprint: It consumes less energy during production and has lower CO₂ emissions compared to cement (García-Herrera et al., 2020).
- Moisture regulation: With a low water vapor resistance factor (μ ≈ 5-10), it allows buildings to “breathe”, prevents indoor condensation, and minimizes biological contamination (Charola, 2000).
- Longevity and repairability: Traditional lime plasters can be easily renewed when damaged.
Limitations:
- Low early strength: Initial strength is low compared to modern cements; careful engineering is required in high load-bearing structures.
- Long curing time: Due to the carbonation process, reaching full strength can take weeks.
2. Natural Stone: Thermal Mass and Energy Efficiency
The use of local stone is advantageous both aesthetically and structurally. It reduces the total carbon footprint by decreasing the energy spent on transportation to the site (Ciancio et al., 2019).
Advantages:
- Thermal mass: Stone walls store solar energy during the day and transfer heat indoors at night, providing passive air conditioning and optimizing energy consumption (Ciancio et al., 2019).
- Longevity and durability: Massive stone structures can last for centuries with low maintenance.
- Aesthetic and cultural value: It preserves the characteristic features of regional architecture.
Limitations:
- Thermal conductivity coefficient (λ): Massive stone walls may require additional insulation layers to meet modern thermal insulation standards.
- Energy requirement for processing and transport: Cutting and transporting stone can be energy-intensive.
- Technical knowledge requirement: Incorrect application can lead to structural weakness and cracking.
3. Organic Binders and Fibers: Building Elements as Carbon Sinks
Straw, flax, hemp, and other natural fibers represent a “carbon-negative” approach when combined with lime or clay (Hernandez & Laustsen, 2018). These fibers absorb atmospheric CO₂, trapping it within the structure and turning the building into a carbon sink.
Advantages:
- Flexibility and crack control: Prevents micro-cracks and balances tensile stresses.
- Thermal and acoustic insulation: Organic fibers improve the insulation performance of building elements.
- Biocompatibility: Natural and recyclable materials adapt to the ecological cycle.
Limitations:
- Risk of biodegradation: If moisture management is not addressed, it becomes vulnerable to microbial attacks.
- Protection requirement: Traditional recipes must be supported by modern biocides or natural preservatives.
4. Holistic Approach: Scientific Support and Sustainability
The integration of traditional materials into modern building technologies is not just an aesthetic choice, but a technical necessity (Minke, 2012). The compressive strength, thermal transmittance (U-value), and chemical compatibility of materials must be determined through laboratory tests (European Committee for Standardization, 2016).
For example, intervening in a historic stone structure with a cement-based mortar can cause irreversible damage due to chemical salt efflorescence and mechanical incompatibility (Charola, 2000).
Advantages in terms of sustainability:
- Low carbon emissions and embodied energy.
- Energy and cost savings through the use of local resources.
- Preservation of cultural heritage and continuation of aesthetic values.
Conclusion
Lime, stone, and organic binders hold strategic and ecological importance from both historical and sustainable building perspectives. When performance limits are supported by modern engineering, laboratory tests, and correct detailing, it is possible to build structures that are both long-lasting and environmentally friendly.
The architecture of the future is rising with traditional knowledge filtered through a scientific lens.
- Ashurst, J. & Ashurst, N. (2013). Practical Building Conservation: Stone, Brick, Mortar and Plaster. English Heritage, London.
- Minke, G. (2012). Building with Earth: Design and Technology of a Sustainable Architecture. Birkhäuser, Basel.
- García-Herrera, R., et al. (2020). “Life Cycle Assessment of Lime-Based Mortars for Sustainable Construction.” Journal of Cleaner Production, 256: 120485.
- Ciancio, D., et al. (2019). “Thermal Performance of Stone Masonry Walls in Historical Buildings.” Energy and Buildings, 198: 125–136.
- Walker, P. (2007). Sustainable by Design: Explorations in Theory and Practice. Earthscan, London.
- Hernandez, P. & Laustsen, J. (2018). “Organic and Plant-Based Binders in Traditional Construction.” Construction and Building Materials, 179: 547–558.
- Charola, A. E. (2000). “Salts in the Deterioration of Buildings: An Overview.” Journal of Architectural Conservation, 6(1): 51–58.
- European Committee for Standardization (CEN) (2016). EN 998-1: Specification for Mortar for Masonry – Part 1: Rendering and Plastering.