We upgraded 48 council homes on Ross Street and Coldham’s Grove to bring them up to a net zero carbon standard.
About a third of carbon dioxide emissions in Cambridge come from homes, mainly from heating. Decarbonising homes is crucial to fulfilling our vision for the whole city to be net zero carbon by 2030. This pilot project explored how we can do that.
We delivered the extensive ‘whole house’ upgrades while the tenants, who volunteered to take part, remain in their homes. As well as reduced energy consumption and emissions, the project’s benefits include:
- improved health and wellbeing
- a more consistent indoor temperature throughout the year
- excellent ventilation and indoor air quality, with no damp or draughts
- reduced risk of damp and mould
- a refreshed and attractive home in good repair
Energy efficiency measures
The homes were built in the 1930s and are some of our least energy efficient properties. Before the upgrades, more than half of all heat lost was through the uninsulated solid brick walls. About a sixth was lost through the floor and roof.
Measures completed to improve the energy efficiency of the homes include:
- adding insulation to the external walls, ground floor and roofs. This will significantly reduce heat loss in winter
- replacing gas boilers with air-source heat pumps, which extract heat from the air to provide heating and hot water. They typically produce about three times as much energy as they use
- installing new mechanical ventilation with heat recovery (MVHR) systems. These replace stale, moist air with fresh, filtered air and reduce heat loss. They also reduce humidity and the risk of condensation and mould
- installing photovoltaic (PV) solar panels on the roofs, to provide electricity for the homes. Over the course of a year, these will contribute to the running of the heat pumps and MVHR systems. They also enable qualifying tenants to claim Smart Export Guarantee payments for any generated energy that property does not use
- installing triple-glazed windows and composite external doors to reduce heat loss, draughts and condensation. These also provide better insulation against external noise
Timeline
Planning permission and building regulations approval was granted in 2023. We then selected Axis as the contractor through a tender process.
Work began in an empty home in May 2024, then in the occupied properties in August.
The main construction phase finished in March 2026, and is covered by a 12-month defects period.
Engagement events
Regular engagement with tenants throughout the project has been important. It has allowed us to communicate the benefits and secured trust in the process.
In September 2022, we held an online seminar for interested tenants. After a presentation to introduce the project, residents could ask questions about it.
In April 2023, we hosted a drop-in event where participating tenants could meet the architects and see the design proposals.
In April 2024, the tenants were able to meet the contractor at a second drop-in event, and ask questions about the upcoming work.
During 2024 and 2025, we hosted regular coffee mornings for participants to ask questions and meet other people taking part.
In January 2026, we hosted a smarter energy session to help tenants learn about their new heating systems and choose appropriate energy tariffs. The event included stalls from National Energy Action and Vaillant, whose demonstration trailer included a working air-source heat pump.
Next steps and further information
We will continue to support the tenants as they adapt to their upgraded homes. This is alongside an extended period of monitoring to understand the long-term performance of the improvements.
The results and other practical lessons from the project will inform our approach to future upgrade works. They will ensure we continue to improve quality, resident experience and delivery.
Visit Action on Energy for further information on how to maximise your home’s energy efficiency, save money on energy bills and cut carbon emissions.
