Optoppen is an innovative construction method designed to address the challenges of urban densification by adding lightweight, low-carbon roof extensions to existing buildings. The approach is rooted in the concept of “topping up” — using the space above existing structures to create additional floor area, maximizing the potential of existing buildings. This sustainable strategy helps to meet the growing demand for housing and office space in urban areas while significantly reducing the environmental impact of traditional development.

A key component of this solution is the Optoppen Web Platform, which offers an easy-to-use tool for building owners, developers, and city planners to assess the feasibility of adding storeys to their buildings. This dynamic platform allows users to model the vertical extension potential of their existing structures, providing real-time data on the additional floor space that can be added, the carbon savings achieved by using timber, and the overall environmental impact of the project.

The Optoppen tool incorporates various parameters, such as building type, structural conditions, and local planning regulations, to deliver a tailored assessment of each project’s potential. This feature helps users understand the limitations and opportunities of their existing buildings and enables them to experiment with different configurations, optimising designs before making any commitments. The tool also highlights the embodied carbon savings of using timber for the new extensions, further reinforcing the environmental benefits of the approach.

On the Optoppen website, stakeholders can access a comprehensive database of case studies, policy insights, and best practices from across Europe. This knowledge hub helps guide the decision-making process by providing detailed examples of successful projects, along with valuable lessons learnt. The platform also fosters a wider conversation on policy and regulatory frameworks that support upward extensions, addressing any potential barriers to implementation.

By focusing on existing buildings, Optoppen presents a practical solution to urban housing and office space shortages, offering a cost-effective, low-carbon alternative to demolishing old structures and constructing entirely new ones. The approach supports the efficient use of resources, reduces construction waste, and contributes to the revitalization of older urban areas. As cities continue to grow and face mounting pressure to meet housing demands, the Optoppen approach provides a scalable and sustainable way to enhance the built environment, all while adhering to carbon reduction goals.

The New Model Building provides a detailed methodology for designing multistorey mass timber buildings in the UK, which meets current guidelines and has the support of insurance companies and warranty providers, increasing confidence in the use of mass timber. The model has been produced by Waugh Thistleton Architects, alongside fire engineers from UCL, structural and sustainability engineers from Buro Happold, and cost consultants from Gardiner & Theobald.

The guidance is divided into a suite of three open-source and easily navigable documents:

• The Guide Book explains why the New Building Model is needed and what it includes
• The Detail Book describes the technical standards used to create the model and includes a collection of construction details, checklists, and performance specifications
• The Evidence Book contains the pre-assessed documents submitted to the national warranty provider NHBC.

With this comprehensive array of information, the New Building Model allows for stakeholders including designers, developers, insurers, and investors to have clarity and confidence to incorporate mass timber into their multistorey residential projects. The framework uses a typical building to show how the details and design principles can be used and is meant to showcase a methodology for timber residential developments in a climate emergency. Included in the guidance is also a detailed moisture management plan, fire strategy principles, acoustic performance information, and construction sequencing.

The New Building Model was developed with the following design parameters:

• Buildings with a height of less than 18m (around 6 storeys)
• Complies with all current Approved Documents and Building Regulations
• No combustible materials used in the external walls (to achieve an EWS1 Form and meet GLA funding requirements)
• Fire compartment in line with REI 60 and K2 60
• Best practice waterproofing and moisture prevention and mitigation
• Mass timber elements including glulam columns and beams, LVL columns and beams, CLT walls and slabs.

A whole life carbon assessment (A-C) was completed for an archetype New Model Building of six stories and 29 flats. Material volumes were calculated from a BIM Model and manufacturer EPDs, and the archetype achieves an A+ LETI rating and results in a carbon savings of 74% compared with an equivalent concrete and steel building. The Model Building would also be quicker to build, as timber frame construction typically can be delivered in a third of the time of traditional concrete framing. Additionally, timber construction is safer, quieter, and requires fewer deliveries. Excluding sequestration, the New Model Building has estimated upfront embodied carbon (A1-A5) of 326 kgCO2e/m2 and total embodied carbon (A-C) of 271 kgCO2e/m2 which meets the RIBA 2030 Built Target.

The New Model Building is intended as a set of design principles prepared for Build by Nature. This guidance meets the current UK Building Regulations and NHBC technical standards but was not intended to relieve any consultant of their responsibility to ensure designs meet suitability, performance, and compliance requirements.

Natural Building Systems has developed a construction system made with biogenic materials to address embodied emissions, operative emissions, and the waste associated with construction. Their system includes lightweight, breathable insulated wall, roof, and floor panels, which are standardised and designed to be efficiently assembled on site and easily disassembled and reused. Natural Building Systems’ primary innovation is the integration of HempSil, a natural insulation made from hemp, with demountable structural cassettes. During its growth, hemp absorbs up to 14 tonnes of carbon per hectare annually and is a good crop to incorporate into sustainable field rotation strategies. When used as an insulation material, hemp absorbs and desorbs moisture in the air, regulating indoor relative humidity and temperature.

The system is also well suited to address other problems typically attributed to the built environment. The panels themselves are self-similar to reduce costs and waste during production, but they can be combined with each other and bespoke components to provide a great amount of flexibility in design. Natural Building Systems’ panels can be delivered flat-packed or pre-assembled depending on the project needs. Assembly and disassembly are both quick and easy due a patented method of securing panels together using timber pegs and T&G cones. This method also allows reconfigurations or alterations to be made without waste.

Natural Building Systems are committed to the circular economy and even provide BIM material passports for all their products. Currently, this system is limited to 11m high buildings for residential use in the UK, but for non-residential uses it can be used for structures up to 8 stories high when paired with a timber structure.

The MykoSlab is an insulation sheet for construction bio assembled from cellulosic feedstock and fungal mycelium.

Mykor’s solution is to create highly performative building materials made from biomass waste. Their fabrication technique involves the use of mycology to propagate mycelium on cellulosic waste from the paper industry, that would otherwise be discarded to landfill or incinerated. Mycelium is the “root” of mushrooms and functions as a natural adhesive.

Mykor insulation utilises 90% less water and 40% less electricity than polystyrene. The Mykor team has estimated that they will be able to repurpose 20,000 tonnes of waste on average each year.

With studies linking air pollution’s negative impact on our health, it has become important to improve the quality of air in our homes. Mykor promotes higher standards of air quality compared with synthetic materials which emit toxins as they degrade. Their materials prevent the accumulation of dampness, they are breathable, vapour-permeable, and free of volatile compounds. The Mykoslab is stronger than EPS and more water resistant than hemp, wool and straw insulation. Its thermal performance is estimated to be competitive with mineral wool while its estimated sound-absorption is 75% at 1000Hz. It possesses good water permeability, and it is non-toxic, VOC free and fire safe (estimated Euroclass B).

Mykofoam can be used as a direct substitution for other insulation products available on the market.

An LCA is currently being produced for Mykofoam, due at the end of April 2024 which can be used in a whole-life carbon assessment.

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 .

Biohm generates a comprehensive picture of a business’ current environmental impact based on the ‘waste’ streams it produces. This data, supplemented with resource testing reveals opportunities for material development, which can help clients decarbonise, bring circularity into the business, reducing costs and adding value.

This service is broken into three steps:

1) RESOURCE MAPPING

To identify ways to help a client decarbonise, Biohm assesses ‘waste’ streams. Data collection and analysis on three or more resources generates an understanding of the company’s carbon flow and environmental impact. This is followed by a comprehensive demonstration of the opportunities for decarbonisation through material development.

​2) FEASIBILITY STUDY

This involves carrying out a schedule of tests and experiments with the ‘waste’ stream with an objective to validate it as a feasible feedstock to create mycelium and / or Orb materials.��Once the success of the experiments is assessed, the decarbonisation potential of the resource can be demonstrated and the possibilities of incorporating it into a circular material and / or product can then be determined.

3) INDICATIVE MATERIAL DEVELOPMENT

Once the ‘waste’ has gone through a feasibility study and is deemed ‘usable’, Biohm produces samples of a unique material incorporating the resource. Testing and optimisation then reveals the material’s properties and potential future application, revealing further product development pathways, demonstrating the possibilities and routes for decarbonisation.

Mycocycle is addressing this problem by using “mycoremediation” to remove the harmful toxins, divert this waste stream from landfills, and create a new bio-based product that can be used as a building product to replace plastics and other petrochemicals.

Mycocycle uses a patent-pending process that harnesses the power of mushrooms to clean harmful toxins from waste streams and create a new bio-based material that can be reused instead of being sent to a landfill where it would either be burned or buried. The waste stream now becomes a resource that creates a value stream in an average of 4-weeks. Although Mycocycle specialise in construction and demolition waste, they are moving into other sectors, such as medical waste, as well. The process is a stand alone solution that can be done on-site and we have been able to reduce PAHs by an average of 95% and Phthalates by an average of 85%.

The resulting material is a more environmentally friendly substitute for industrial uses such as Styrofoam, insulation, packaging, building materials and multiple other applications where plastics have been previously been utilised. It is lightweight, has insulative properties and offers water and fire resistance.

Costs equal the current national average of landfilling materials. Mycelium composites are cost competitive with both synthetic foams and wood products, with the raw materials of mycelium composites (0.07-.17/ $US/kg) constituting the cost of the agricultural and industrial by-products used to make them much lower than the wholesale price of polystyrene (2.1-2.3 $US/kg), polyurethane (8.2-10.4 $US/kg), phenolic formaldehyde resin (1.7-1.9 $US/kg), foams and plywood (0.5-1.1 $US/kg), softwood (0.7-1.4 $US/kg) and hardwood (3-11 $US/kg) products.

Taken from: Engineered mycelium composite construction materials from fungal biorefineries: A critical review Mitchell Jones a,b, Andreas Mautner b, Stefano Luenco c, Alexander Bismarck b,⁎, Sabu Johna,⁎ a School of Engineering, RMIT University, Bundoora East Campus, PO Box 71, Bundoora 3083, VIC, Australia b Institute of Material Chemistry and Research, Polymer and Composite Engineering (PaCE) Group.

Accoya® wood combines the sustainability benefits of carbon sequestration and storage with durability, stability and performance. Accoya® modified wood transforms fast-growing FSC® certified wood into a building material with characteristics that match or better those of man-made, intensely resource depleting and heavily carbon-polluting alternatives. Accoya® is a modified wood that under goes a proprietary acetylation process that enhances the properties of the wood, making it more dimensionally stable and extremely durable without compromising its inherent benefits.

Accoya® wood supports customers and end-consumers in reducing embodied carbon, maximising carbon storage, and also reducing operational carbon costs for the end consumer with exemplary energy efficiency credentials for windows and doors. High durability and resistance to decay also means less frequent repair and replacement timings, reducing lifetime costs and environmental impacts. And, thanks to Accoya’s superior thermal insulation and minimal shrinking or swelling, heat lost through timber windows and external doors is reduced, which helps to keep homes warm and energy bills down.

Additional major product categories for Accoya use include decking and cladding, and it can be used in water –�� even for long term use. For example, it has been used in canal linings in the Netherlands and Accoya has also recently been used by the UK Environment Agency to replace one of their hardwood fenders in the Thames, showing how these important ecological support structures can be more sustainable without compromising quality or effectiveness. Accoya offer an unrivalled 50-year warranty for wood durability and a 25-year warranty in ground or freshwater.

What Accoya believe sets them apart is how it enhances the performance and durability characteristics of wood, multiplying the ‘green’ impacts of timber as a building material through longer product life, increased suitability for multiple applications, and circular economy credentials. Data, testing and certifications are available to confirm Accoya’s quality and sustainability credentials, including FSC®, LEED, BREEAM, Declare, Green Star, Green Label, Dubokeur, KOMO and more.

Accoya’s Cradle to Cradle (‘C2C’) Certified® Gold level is perhaps its most prestigious and differentiating accreditation. C2C assessment criteria include the circular properties, material health (toxicity), renewable energy use, water and waste impacts, and social factors of our product and its production. With the highest possible Platinum rating for Material Health, Accoya demonstrates its friendliness to people, pets and the planet: non-toxic with no risk of harmful chemicals leaching out, no contribution to microplastic waste, and it can be recycled or used as biofuel like any other wood at end of life. Responsible sourcing is also assured, with 100% of Accoya sourced from certified sustainable (FSC®) wood sources.

Since Accoya is a material that is used to make products for multiple applications, initial cost and ROI vary greatly. However, for a relatively small initial premium, the benefits offered in return are extended service life and reduced maintenance of coatings. For example, compared to hardwood, an Accoya sliding sash window would cost approximately 10% more, but last at least twice as long and require repainting 2-3 times less frequently. And compared to western red cedar cladding, Accoya cladding would cost approximately the same yet last twice as long.

Gramitherm��is an insulating panel made from natural grass.��Gramitherm��exhibits high��thermal capacity,��performance��and��sound absorption properties.��Compared��with other commonly used��insulating��materials,��Gramitherm��offers:

• A low carbon material. 1kg of Gramitherm batt absorbs 1,405kg of biogenic carbon during the growth of the grass.��
• It is a natural, clean form of insulation both against cold and heat. The product has a thermal conductivity of 0,0405W/m.K, a thermal capacity of 1500 J/kgK and a with a phasing time of 9 hours (240mm). Gramitherm brings a sound absorption of 0,99 at 1000 Hz frequency.��
• The energy used in the production of Gramitherm is 20% less than that consumed by insulation products such as extruded polystyrene. Life Cycle Assessment information is available.����

Gramitherm costs 85 Euro per m3 (quoted pre-Brexit, please contact Gramitherm for accurate up-to-date pricing information).