Low-Carbon Roof Extensions to Existing Buildings

Construction method adding lightweight, low-carbon roof extensions to existing buildings

Climate Change Mitigation Resource Use Retrofit Advancing Net Zero Circular Economy

Problem Addressed

Given the ongoing housing crisis, there is an urgent need to maximise the use of existing infrastructure while minimizing the environmental impact of new development. Traditional construction practices often result in significant resource consumption, waste, and carbon emissions, especially when buildings are demolished to make way for new ones. To meet the rising demand for urban housing and office space, cities must find solutions that allow for densification without expanding onto rural land. Optoppen addresses these challenges by offering a sustainable, low-carbon solution for expanding the usable space within existing urban environments.

Solution Overview

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.

Company name

Whitby Wood

UK availability

Yes

Solution launch date

November 2024

Solutions submitted by

Whitby Wood

Case Study

Located in London, the Arding & Hobbs building underwent a transformative renovation that added 1,500 m² of space through the addition of two storeys. Completed in 2023, this project was led by W.RE (W Real Estate) with architectural design by Stiff + Trevillion, and collaboration with B&K Structures, AKT II, and Knight Harwood.

The project’s new roof pavilion was constructed using Cross-Laminated Timber (CLT) framing and finished with a unique scalloped brass cladding. This addition was paired with an innovative raised curtain wall system, incorporating bespoke brass and bronze cladding, supported by a steel framing system.

The revitalised building showcases a commitment to sustainability, earning a BREEAM ‘EXCELLENT’ rating and receiving multiple accolades in 2021, including the ATA Awards for Office, Future Projects, and Stakeholder Engagement. The project highlights the potential of CLT in creating energy-efficient, low-carbon spaces while enhancing the value and functionality of existing buildings.

Up to 630,000

40 %

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