Design Strategies IMPULSE - Sustainable Facades Vol 2

Figure 32. Density
Figure 36. Summary of comparative analysis
Figure 33. Thermal Conductivity
Figure 34. Heat Capacity
Figure 35. Compressive strength
Figure 35. Sound reduction (dB)
The U-value, expressed in W/m²K, represents
the overall heat transfer coefficient of a building
element or product. It‘s calculated using the
equation U-value = thermal conductivity (λ) /
thickness (d). This value indicates the rate at which
heat is transferred through one square meter
of the structure, divided by the temperature
difference across the structure.
Compressive strength is the strength of a
material loaded in compression. For load-bearing
structures (1-2 stories) a compressive strength
of 0.1-0.2MPa is sufficient, but for safety reasons
and after the safety factors are applied, the
compressive strength should be ca. 2-2.5 MPa [2].
As Fig 35 shows unfi red earthen products,
rammed earth and cork present the highest values
of compressive strength, while hemp lime product
presents a slightly lower value of compressive
strength but still a sufficient compressive strength
of more than 2 MPa. On the other hand, straw
products have very low values, less than 1 MPa
which means they are not suitable as load-bearing
materials.
Fig 36 represents the sound reduction capability
of the materials. From this graph, it is noticed that
Rammed earth and Hemp lime products present
the highest sound reduction. In a project where
acoustic performance has a high priority, these
materials can be a better choice.
Different comparative analyses result that
different materials may belong to multiple
categories depending on their applications
(Fig 37), each offering unique benefi ts and
considerations. While biodegradable materials
require careful design to avoid moisture issues,
cork stands out for its water resistance, alongside
stabilized earthen structures. Conversely, straw
products necessitate robust water protection due
to susceptibility to rot. Despite this, straw remains
cost-effective and widely available, boasting
favorable thermal and mechanical properties,
ideal for eco-friendly construction projects.
8. Conclusion
This study provides valuable insights into the
practical implementation of biodegradable
materials in envelope design, equipping
architects, engineers, and builders with informed
decision-making tools. Biodegradable materials
offer numerous benefits, including renewability,
reduced environmental impact, and compatibility
with circular economy principles,
while also enhancing structural integrity and
indoor environmental quality. „Building for the
Future: A Guide to Biodegradable Materials
in Envelope Design“ aims to inspire industry
professionals and researchers to embrace
these materials for a more sustainable future,
leveraging advancing technology to further
enhance their performance and unlock their full
potential in sustainable construction endeavors.
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Design Strategies IMPULSE – Sustainable Façades 04.2024 Design Strategies IMPULSE – Sustainable Façades 04.2024
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