The construction sector is one of the largest contributors to global greenhouse gas emissions. A significant share of these emissions is generated long before a building is occupied, through the production, transport, and processing of construction materials as well as during the construction phase itself. These so-called embodied emissions are effectively locked-in once a building is completed and can no longer be reduced.
In response to this challenge, the European research project INBUILT is developing real demonstration buildings to explore building practices that are more resource-efficient and climate-friendly. The project is implemented by a consortium of research institutions and industrial partners with the shared goal of bringing sustainable construction solutions from research into practice.
A real world demonstration: the INBUILT tiny house
One of the INBUILT demonstration sites is a mobile tiny house located in Pfeffenhausen, Germany. Designed as a compact yet realistic test environment, the tiny house integrates innovative, circular building materials into a single structure and observes their performance under real conditions.
The main objective of the demonstration site is to show how alternative construction materials and building systems can be applied and what environmental and functional benefits they can offer. A particular focus is placed on reducing CO₂ emissions, minimising resource use, and enabling the reuse of building components.
The project addresses professionals from planning and construction, students, researchers, and interested visitors, supporting further development and wider adoption of sustainable building approaches in the long term.
Testing sustainable building materials under real conditions
The mobile tiny house is deliberately designed as a comparative building. It consists of two separate room units that are connected under a shared roof. Although similar in size, the units differ fundamentally in their construction.
One half of the tiny house is built using prefabricated external wall elements made from reclaimed wood. These elements are developed and prefabricated at the Karlsruhe Institute of Technology in Karlsruhe and then transported to Pfeffenhausen. The interior surfaces are finished with straw–clay boards, which can contribute to a balanced indoor climate.
The other half of the building is constructed on site using fired bricks containing a high share of recycled and reused materials, provided by the project partner Leipfinger-Bader. Inside the building, the two halves are separated by an internal partition wall made from recycled concrete. The system is complemented by smart windows featuring bio- based frame materials and recycled glass.
A central design principle of the tiny house, particularly for the reclaimed-wood construction, is design for disassembly. The wall elements are assembled using wood-to-wood connections without adhesives or permanent fixings, allowing the components to be dismantled and reused at the end of their service life.
After completion, the tiny house will be continuously monitored over a period of approximately one year to record parameters such as temperature, humidity, and energy consumption, providing valuable data on material performance under real operating conditions.
Minimising embodied CO₂ in the building sector
Overall, large share of the materials used consists of reused and recycled components. At the same time, the wall system is designed to achieve high thermal performance, reducing energy demand during operation. The material composition and layered structure are also expected to support a stable and comfortable indoor climate.
The reclaimed-wood external walls of the tiny house are designed to significantly reduce environmental impacts. Compared to conventional concrete wall elements, INBUILT targets a reduction in lifecycle CO₂ emissions of up to 80%. Energy use during material production and the amount of construction waste are also expected to be substantially lower.
The bricks, which form the second half of the tiny house, are fabricated using significant portions of 20% recycled and 50% reused materials. These originate, for instance, as waste from brick processing or excavation procedures. Bio-based filling of the bricks, further enhancing thermal parameters, is directly reused from old bricks coming from building dismantling. This significantly lowers the carbon footprint and enhances sustainability.
Beyond technical performance: making sustainable construction tangible
Beyond its technical function, the tiny house also serves an educational purpose, making sustainable construction tangible and accessible. For students and professionals, the demonstration site offers a valuable learning environment where innovative construction approaches can be observed at full scale.
At the same time, the demonstrator aims to show that sustainable building is not a distant future vision. Climate-conscious construction can already be realised today using available materials, established building processes, and practical solutions.
By integrating innovative materials and circular design principles into the tiny house, INBUILT highlights how research, industry, and practice can work together to support the transformation of the construction sector into to a more resource-efficient and low-carbon built environment.
This article was written by Natascha Steiner (KIT) and Fabian Teubl (HeiQ) and curated by Giorgio Alessandro (Greenovate! Europe) for the INBUILT project.
