Feldballe School

A school extension built from straw and timber proving that bio-based materials can meet the performance demands of modern public construction.

Place

Rønde (Denmark)

Architect

Henning Larsen Architects

Size

250 m²

Year

2022

Project Overview

The Feldballe Free School extension is a 250 m² educational building completed in 2022 in Rønde, Denmark. Designed by Henning Larsen Architects and developed in partnership with EcoCocon, with support from the Danish philanthropic organisation Realdania, the project was built around five principles: bio-based and renewable materials, reuse of local resources, toxic-free construction, healthy indoor climate, and design for disassembly.

The building envelope is formed by 154 m² of EcoCocon prefabricated straw wall panels, finished internally with clay plaster and externally with thermally modified Nordic pine cladding. The roof is constructed entirely from certified, locally sourced timber. An innovative eelgrass ventilation system — developed specifically for this project — allows air quality and humidity to be automatically regulated without mechanical ductwork, keeping rooms spacious, high-ceilinged, and free of toxic finishes throughout. Solar panels on the roof further reduce operational energy demand.

The project was awarded the Danish Design Award in the category of Better Learning.

PROJECT PARTNERS

Architect: Henning Larsen Architects
Funding Partner: Realdania
Contractor: Høgh & Sønberg
Client: Feldballe Free School

Thinking critically about the production line in its entirety, we have shown that quality and function are not compromised by using fewer resources. Straw is a fast-growing renewable resource and a byproduct of agriculture — a great alternative to producing new materials.

Jakob Strømann

Director of Sustainability and Innovation, Henning Larsen Architects

KEY FEATURES

250 m² school extension, completed in 2022
154 m² of EcoCocon straw wall panels
Natural and passive ventilation with eelgrass air filters — no suspended ceilings, no large ductwork
Clay plaster interior walls supporting diffusion-open performance
32 solar panels (10 kW total) integrated into a timber roof structure
Designed for full disassembly — all components screwed, not bonded

IMPACT

Approximately 17.8 tonnes of CO₂ are stored in EcoCocon straw panels
The whole-life carbon cost of the building is less than 150 kgCO2e/m²
Operational carbon footprint: 6 kgCO₂e/m²/year over a 50-year lifespan — well below Denmark's regulatory threshold of 12 kgCO₂e/m²/year

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What Do People Say about EcoCocon?

Seeing natural materials delivered with factory precision was compelling, resulting in a home that far outperforms conventional construction in comfort and performance.

Brandon Clemenson

Stanley Bragg Architects

We work with EcoCocon products because they enable healthy, ecological, and sustainable construction while respecting both the environment and future homeowners. Their thermal performance, bio-based design, and ability to create durable, highly efficient building envelopes reinforce our commitment to this partnership.

Joahn Jaegli, EO Bois

France

EcoCocon integrates well into my design process, combining high-precision prefabrication I can rely on with efficient time-saving design and precise on-site execution.

Carl-Fredrik Johansson

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