Berlin becomes the stage for climate-smart construction

 Thursday, September 11, 2025

Berlin is unfolding a unique experiment regarding the construction industry. A recent pioneering research project seeks to revolutionise public housing with sustainable, low-carbon materials. In 2019, the STADT UND LAND Wohnbauten-Gesellschaft, a major urban housing company, launched the “Holz Ziegel Lehm” (Wood, Brick, Clay) initiative, a practice-based study designed to test the viability of mass timber construction under the real-world pressures of budget constraints, regulatory demands, and the need for efficient, mechanised processes.

This ambitious project was a direct response to the climate crisis. With the construction sector responsible for a significant portion of Berlin’s raw material consumption and greenhouse gas emissions, the city recognised that simply building energy-efficient homes was no longer enough. The very materials used to create a building’s shell and structure are often carbon-intensive, negating the benefits of later operational efficiency. The “Holz Ziegel Lehm” project aims to provide the tangible, data-backed evidence needed to shift the industry toward a more sustainable paradigm. The research, which is supported by the Berlin Senate Department for the Environment, Transport, and Climate Protection, is divided into two distinct subprojects, each serving as a “living laboratory.”

A tale of two buildings

Subproject A, located at Alt-Britz 107, is a head-to-head comparison of two different construction methods. On a single plot, two identical five-story residential buildings were erected, each housing 36 subsidised rental apartments with identical layouts. The critical difference lies in their core materials: one is a mass timber skeleton structure, while the other is a traditional monolithic brick building. Both buildings feature clay plaster for interior finishes, a choice that naturally regulates indoor humidity and temperature, effectively eliminating the need for energy-intensive air conditioning.

This side-by-side study is being meticulously monitored by researchers from TU Berlin, the University of Stuttgart, and TU Braunschweig. Their goal is to gather long-term, evidence-based data on the buildings’ performance, comparing both their embodied carbon footprint—the emissions generated during material production—and their operational energy efficiency. The findings are expected to provide a clear, scientific basis for future urban planning and material selection in public housing.

The power of prefabrication

A key component of the mass timber building is the Cross-Laminated Timber (CLT) system from Stora Enso, delivered as a complete “Sylva™ kit of parts.” This prefabrication approach is at the heart of the project’s success. The precision-engineered components were manufactured off-site by partners MAX Holzbau, reducing the margin for error and dramatically accelerating the on-site assembly process.

For contractors and developers, the benefits of this approach are substantial:

• Speed and efficiency: The pre-cut and pre-assembled Sylva CLT walls and floors allowed for rapid construction, significantly shortening project timelines and minimizing disruption to the surrounding neighborhood.
• Reduced waste: With components arriving on-site ready for installation, the amount of construction waste generated was minimal, contributing to a cleaner, more organised worksite.
• Predictable performance: The factory-controlled manufacturing process ensures that mass timber elements meet exacting standards for durability and performance, including rigorous fire and acoustic regulations required for public housing.
• Carbon sequestration: The project demonstrates the immense climate benefit of using wood. The manufacturing of the Sylva kit for the building generated just 24 tonnes of CO₂e, a small fraction of the 341 tonnes of carbon that the wood from sustainably managed forests will store for generations. By choosing mass timber over non-renewable alternatives, the project avoided an estimated 511 tonnes of greenhouse gas emissions.

The wood for these materials was sourced from PEFC-certified forests, ensuring that it comes from responsibly managed sources that maintain biodiversity and ecological health.

Beyond the Alt-Britz location, Subproject B at Buckower Felder further expands on the concept of sustainable urban housing. This building maximizes the use of timber in its structure and interior, while also incorporating other recycled materials like processed concrete to further reduce its environmental footprint.

The “Holz Ziegel Lehm” initiative is more than just a single construction project; it is a replicable model for the future of the construction industry. The data being collected will serve as a powerful tool for architects, engineers, developers, and policymakers, proving that low-carbon construction is not only feasible but also scalable and economically viable. By demonstrating how a mass timber approach can meet the complex demands of urban public housing, Berlin is paving the way for a new generation of buildings that are not only affordable and durable but are also active contributors to a healthier planet. This is a clear signal to the global woodworking industry that its products are at the forefront of the fight against climate change.

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Tags: cross-laminated timber (CLT), prefabricated construction, public housing, sustainable construction, timber architecture, urban development