Making existing buildings net zero operational carbon

Run from 24/08/20 - 25/09/20


Amongst all the chaos of 2020, two things kept happening: the world kept warming and organisations kept making net zero carbon commitments. Over the next nine years, we need to halve both the energy use of the UK’s buildings and global carbon emissions. Meeting this challenge requires an innovative approach to finding and adopting solutions to ensure swift and radical transformation across the built environment industry.

The World Green Building Council’s (WorldGBC) Advancing Net Zero campaign promotes and supports the acceleration of total sector decarbonisation by 2050. As part of this campaign, in 2019, the UK Green Building Council (UKGBC) published ‘Net Zero Carbon Buildings: A Framework Definition’ to provide the industry with clarity on how to practically achieve net zero carbon in construction and operation, supporting those who align with WorldGBC’s Net Zero Carbon Buildings Commitment (The Commitment). The Commitment challenges signatories
to reach net zero operating emissions in their portfolios by 2030 and to advocate for all buildings to be net zero in operation by 2050. By January 2021, 94 business and organisations, 28 cities and 6 states and regions have already signed this commitment, including 42 UKGBC members. These numbers are rising rapidly.

Addressing the climate and ecological crises, and their associated social impacts, is too great a challenge for any one organisation to tackle alone. To make ambitions like The Commitment
truly achievable requires collaboration and knowledge-sharing to increase both awareness and adoption of sustainability solutions across the built environment industry. So many of the solutions for net zero already exist but are often not common knowledge or well understood. UKGBC is uniquely positioned to convene our membership and the wider industry towards this common goal.

Challenge context

The global Net Zero Carbon Buildings Commitment requires companies, cities, states, and regions to reach net zero operational carbon emissions in their buildings by 2030. For the UK, this translates to halving average operational energy use within the same timeframe. Through this challenge we wanted to uncover what owners of existing buildings can do right now to significantly reduce operational energy use and carbon emissions with minimal physical intervention and disruption.


How can a building owner improve their existing buildings, with as little physical intervention as possible, to achieve net zero operational carbon by 2030?


The solutions received in response to this challenge ranged from whole house retrofits to smaller more specific interventions. Five of the solutions we received, which were deemed to address this challenge well, are highlighted over the next few pages.

Biogen Systems

Biogen Systems involves a modular Combined Heat and Power (CHP) system housed within 20 ft shipping containers fuelled by virgin or waste biomass. The system is deployed to site with complementary technologies that support and reflect the requirements or opportunities of individual sites e.g. microgrid, battery storage, solar, wind and cooling. Their goal is to provide bespoke Biomass CHP configurations to deliver power, building processes, heat and cooling.

Biogen Systems are currently working with Carbon Footprint Ltd to assess and then offset Scope 1, 2 and 3 emissions to achieve formal carbon neutral accreditation. The system itself produces a biochar that results in its operation being carbon negative. The technology does require sufficient space for fuel storage (typically 15m by 5m), which would preclude some sites. However, it does not require changes to typical heating systems i.e. it is a “2 flange system”, feeding hot water into conventional systems via one flange and receiving the return water via a second flange, as a typical fossil fuelled boiler would. Biogen Systems would carry out all installation work, making the process no more complex than installing a conventional system.

Energiesprong UK

Energiesprong is a whole house refurbishment or new build standard and funding approach for social housing providers. Developed and proven in the Netherlands, where thousands of homes are retrofitted each year, Energiesprong UK aims to scale this approach in the UK market. An Energiesprong retrofit uses money that would normally be spent on energy bills and maintenance to pay for the works, ensuring the cost of living does not increase. Installers must ensure the retrofit is net-zero energy over the year, with performance guaranteed in the long-term and verified by real life monitoring.

Energiesprong can deliver a whole-house retrofits in just 10 days, providing minimal disruption to residents. The retrofits are guaranteed to be net zero energy, including real life monitoring, and targeted at social housing. Therefore, if scaled, this solution alone could significantly contribute to making UK housing net zero operational carbon by 2030.

Etopia Uplift

Etopia Uplift, developed for existing housing stock, is where net-zero builder meets tech giant, Etopia powered by Samsung and Isla. Following on from the partnership signed between Samsung and Etopia in 2020 for new builds, they are now turning their attention to the decarbonisation of existing housing stock, releasing a technology-led solution to the industry with favourable costs and installation packages. The solution is made up of an air-source heat pump (ASHP), Smart home technology -‘Isla’, and renewable energy technologies.

A technology-led approach provides opportunity to prevent a full fabric intervention when increasing the energy efficiency of homes. Once the ASHP, upgraded radiators and Isla tech has been installed, Isla
uses sensors to diagnose any fabric requirements. For instance, identifying which rooms are causing the most heat loss, targeting the issue and reducing costs. Isla can monitor and manage the energy usage across all technology, including the ASHP, to ensure maximum efficiency is met whilst giving a lifestyle smart home function, interoperable with existing smart tech. Tests on various house types indicate this system could increase the average EPC rating from 60 (D) to up to 90+ (A) without requiring any fabric intervention, depending on building construction.


Radbot is a novel ‘smart’ thermostatic radiator heating control. It uses a combination of sensors
and an embedded learning algorithm to detect and predict room occupancy. It then heats each room to a set temperature when it is in use and automatically reduces the temperature when it is empty. This enables automated room-by-room zoning that reduces unnecessary overheating and saves energy in unoccupied zones without impacting occupant comfort. Radbot does not require scheduling via an app or WiFi connectivity.

Radbot takes minutes to install with no specialist skills required, resulting in a low-cost product that has the potential to be retrofitted to existing UK homes at scale. To achieve net zero this solution would need to be considered as part of a suite of solutions, but as a standalone product it can be installed quickly with minimal physical intervention and substantial energy and carbon savings. modules are building integrated photovoltaic construction elements that replace  conventional roofing and facade materials. Electricity is produced in a thin photovoltaic layer that covers the metal sheet. The series connection of modules is made under the roof sheeting between the battens. can provide on-site electricity via system installation that is as easy as installing any standard seam metal roof. The traditional aesthetics of the roof also aim to encourage more homeowners to consider solar energy. Environmental impact analysis undertaken by has shown a single 10kW roof will avoid emitting 300 tons of CO2, and approximately 80 million houses in Europe are suitable for installation. aims to reduce CO2 emissions by 200,749 tons annually by 2025.

Content within the solutions library is supplied by the solution providers and UKGBC offers no commercial endorsement of individual solutions mentioned. Solutions are showcased as a source of inspiration, and we do hope that you follow up with the innovators to find out more.