Bio-based modular wall system made of timber and straw

A construction system that brings sustainable and healthy living.

Climate Change Mitigation Health, Wellbeing and Social Value Resource Use Advancing Net Zero

Problem addressed

The built environment is directly responsible for 25% of UK emissions, lifting to 42% if you include surface transport. According to EcoCocon, over the lifetime of a building, materials alone make up to 49% of its overall carbon emissions.

Solution overview

EcoCocon is a modular system for building external walls. It consists of structural timber-straw panels, an airtight membrane, a layer of insulating fibre board and interior clay plaster. The system fulfils the highest quality requirements, including the German Passivhaus Standard. EcoCocon’s natural construction system makes the most of a bio-based and rapidly renewable resource – straw, while offering Passivhaus thermal performance, thus reducing the carbon footprint significantly over the whole life cycle of a building.

The panels are made of 98% natural renewable materials (10% timber and 89% straw) and are Cradle to Cradle certified. They were designed to have minimal ecological footprint and to be safely returned to nature after use. The wood comes from sustainable forestry, and the straw is sourced at local farms. Used in their raw states, the production process demands very little primary energy. Both materials sequester large amounts of CO2 through photosynthesis over their life. This CO2 is then safely stored in the construction until end-of-life which is expected to be 75 years according to their EPD.

A coat of allergy-free, non-toxic interior clay plaster passively regulates indoor humidity and helps to keep it at optimal levels. The entire system is permeable to vapour and with no thermal bridges and airtight, it leaves no space for draughts or mould. Natural materials create a healthier indoor microclimate with even temperatures – warm in winter and cool in summer. Exterior wood fibre layer protects the airtightness and helps to achieve the Passivhaus standard in cold climates.

EcoCocon panels are custom-made for each project. A whole building can be assembled in very little time compared to traditional construction. Installation of panels is a 100% dry and waste-free process.

The system has a U-value of 0.12 W/m^2K.

Similar to buying organic food, using healthier and more sustainable natural alternatives is always slightly more expensive compared to industrial products. The cost of a project built with the EcoCocon straw wall system varies and depends on many factors, such as location and building design. However, with optimal planning and implementation, such a project may cost approximately the same as a conventional build.

The true cost-efficiency comes in the form of additional benefits the solution brings. Thanks to straw’s excellent thermal performance, EcoCocon buildings are very energy-efficient, allowing for massive energy-related savings in the long run. Heating expenses in buildings built to the Passive House standard – which is easily achievable with EcoCocon – can be up to 90% lower compared to typical houses, according to the Passivhaus Institute.

The construction time is significantly lowered with easy and rapid installation of the modular system on site. The resulting buildings are of higher quality with low operating expenses and healthier indoor microclimate.

For more information about EcoCocon’s sustainability metrics, refer to their Environmental Product Declaration.

Company name

EcoCocon

UK availability

Yes

Solution launch date

2011

Case study

This first UK application of the EcoCocon straw wall system is a single storey detached home which sits snugly within its rural surroundings. The team persevered through a 4 year planning process resulting in an efficient, spacious, and simple self-build.

Old Holloway is a prime example of how natural materials, such as straw and wood, can be effectively used to reach the Passivhaus standard. The property’s highly-insulated walls constructed using timber-straw panels, ensure minimal heat loss, resulting in an extremely energy-efficient house. Moreover, the use of natural materials reduces the environmental impact of the construction process, while also providing a cost-effective solution for insulation. The result is a comfortable living environment for the owners, with minimal energy consumption and heating bills, making it a prime example of how sustainable housing can be both cost-efficient and environmentally friendly.

The prefabricated system allowed for rapid and precise construction. The external walls were erected in three days and the house was watertight in four weeks. The large south roof overhang, in combination with simple manual external blinds to the south-facing bedroom provides a simple way of minimising the risk of overheating. Each space has an openable window which can be left open on tilt-in overnight. Monitoring during the first 5 years confirmed 0% overheating. Conversely, the house requires very little heating even in a cold winter.

While modest in size and budget, Old Holloway is spacious thanks to the open cathedral ceiling. The house was built for a price comparable with a regular house, costs almost nothing to heat, and is a testament to what Passivhaus design and bio-based materials can achieve.

Old Holloway has been widely recognized for its success. The project has been featured in various media outlets and championed by the Passivhaus Trust.

98 %

0.12 W/m^2K

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