The building sector represents 40 percent of Europe’s energy demand, 80 percent of it from fossil fuels. Driven by the convenience, familiarity, predictable supply chain and other short-term advantages, we have preferred resources like cement and fired bricks that make up for 12% of our total carbon emissions worldwide. This makes innovation in carbon neutral building solutions urgent.

One of the biggest opportunities to drastically reduce the carbon footprint of the built environment is earth (also known as soil or “leem”), an abundant and eco-friendly building material. In the pursuit of sustainable construction materials, unfired stabilized earth bricks have emerged as a viable alternative, especially in regions like the South of the Netherlands, where natural resources are abundant. Earth bricks save up to 95% in carbon emissions compared to concrete and fired bricks and are completely organic, making them promising circular materials. These bricks are also cost-effective and possess excellent thermal properties. Despite their benefits, earth-brick projects are rare in the Netherlands, highlighting the need to start considering earth seriously in the mix of circular building materials and start to utilize its unique potential.

For a breakthrough of earth as a carbon neutral building material, CoolBricks BV together with Avans. University of Applied Sciences and HZ University of Applied Sciences, have identified various key challenges in the R&D roadmap of stabilized earth bricks. One of them is to improve water resistance of earth bricks while keeping the cost low and material truly circular.

Assignment description

Earth bricks are unfired bricks that are made by mixing soil, water and a binder (optional), and drying the bricks for several weeks at room temperature or under sunlight. Water resistance of earth bricks can be improved by adding stabilisers such as cement or lime. However, there is a pressing need for low-cost, ecologically sensitive and truly circular alternatives. Hence, we turn our attention towards bio-based solutions. CoolBricks has developed 100% circular bio-stabilized bricks, with improved water resistance of 50X as compared to un-stabilized (no binder) earth bricks. However, the water resistance of these bricks is still not comparable to concrete or fired bricks. In this assignment, we want to develop a biological binder to enhance water resistance of earth bricks and study the key performance data (mechanical, durability) on brick level of these biological binders.

  • Work closely with supervisory team and CoolBricks to plan, execute, and monitor research experiments related to improving performance of compressed earth blocks.
  • Collaborate in data collection, analysis, and interpretation from laboratory tests and field trials.
  • Contribute to optimizing compressed earth blocks formulations to enhance water resistance, in partnership with CoolBricks, with respect to biological binders and their economic feasibility
  • Determine the influence of the different variables (compaction force, water content, soil types etc) on the performance of compressed stabilised earth bricks.
  • Casting of bio-stabilized bricks, preparation of various test set-ups mimicking Dutch weather scenario’s
  • Prepare comprehensive research reports, presentations, and academic publications.
  • Maintain meticulous records of experimental procedures, data, and outcomes.
  • Engage in comprehensive literature reviews to support the research objectives.
  • Any other research related tasks that may be assigned by the research team at CoolBricks.


We are looking for motivated and curious students that are able to carry out independent laboratory research:

  • Demonstrated interest in sustainable construction practices and research.
  • Familiarity with construction materials testing, experimental design, and data analysis.
  • Basic understanding of soil mechanics and material characterization techniques
  • Proficiency in relevant data analysis tools and software.
  • Exceptional written (technical writing) and verbal communication skills. Fluency in English.
  • Ability to collaborate effectively within a research team and with external partners like CoolBricks.
  • Prior research experience in earthen construction materials is advantageous.


  • Opportunity to contribute to innovative research with direct practical applications and a tangible impact on society.
  • Professional development opportunities and networking with experts in the field.
  • Collaborative and engaging academic environment within leading sustainability experts from CoolBricks, Avans and HZ

Practical details

  • The proposed starting date is the beginning of September 2024.
  • The duration of the assignment is 5 months.
  • The location will be hybrid but mainly based in Utrecht or on campus in Breda.

Application process

Interested candidates should submit their application documents by September 1, 2024:

  • Updated Resume / CV highlighting relevant education and experience.
  • Cover letter outlining motivation for applying and alignment with the research project’s objectives.
  • Copies of academic transcripts and relevant certificates.
  • Contact details of two academic or professional references along with your CV.

Please send your application documents merged into one pdf file to Only shortlisted candidates will be contacted for interview scheduling.

Please visit the CoolBricks website for more information.

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