Kent Council Whole-Borough Energy Strategy.

Long-Term Energy Strategy in Action

Helping one of the UK’s most ambitious councils hit net zero by 2030:

In 2019, Gravesham Borough Council declared a climate emergency. They set a target to commit to: net zero by 2030.

What followed was an evolving strategy, with Carbon3 as the principal contractor making it deliverable since 2021. Every part of the programme is coordinated by Carbon3 from end to end.

The results, across five years and multiple funded programmes, are unambiguous. Gravesham has increased the number of homes at EPC A to C by almost 50%. D to G rated stock has fallen by nearly 65%. Housing stock carbon emissions are down 3,916 tonnes, which is a 28.6% reduction.

The council now ranks in the top ten local authorities in England for social housing EPC performance. Every council vehicle is now electric.

The partnership has been shortlisted for three Unlock Net Zero awards in 2026.

These results are only possible with a client who knows what they need to achieve, a principal contractor who knows how to achieve it, and good communication between the two for the entire programme duration.

The funding structure

Gravesham’s decarbonisation programme has run across three Social Housing Fund waves, each building on the last. Wave 2.1 established the foundations, bringing the worst-performing homes up to a baseline standard. Wave 2.2 extended that work with low-carbon technologies at scale. Wave 3, currently underway, is the largest phase yet, covering more than 420 additional homes.

The Warm Homes: Social Housing Fund has covered the core measures required to reach EPC C. What makes the Gravesham programme distinctive is what sits alongside that. The council has consistently chosen to go further than the funding requires, commissioning additional measures beyond the EPC C threshold and paying for them directly. Because the target is net zero, not compliance, and the difference these measures make to residents is non-trivial.

Carbon3 has been the principal contractor across all three waves. The same team, the same systems, the same quality standards, which matters when you are trying to build a coherent borough-wide asset base rather than a patchwork of separately procured projects. We’ve also kept a comprehensive asset register so that none of this impactful work gets lost.

Wave 2.1

Wave 2.1 was where the relationship was established and where the delivery model was tested. Fabric measures came first: cavity wall insulation, loft insulation, bringing the building fabric up to a standard that would support the low-carbon technologies to follow. Installing a heat pump in a poorly insulated home is an expensive way to heat a draughty building. The sequencing was deliberate to provide the best possible results for the resident, rather than the EPC rating.

The programme covered a significant portion of the social housing stock, identifying the properties most in need and designing measures around the specific characteristics of each building. Carbon3 handled the full scope, including surveys, energy performance modelling, design, installation, sub-contractor management, and lodgement. Where road closures were required for access or materials, Carbon3 coordinated directly with the local authority. Residents were engaged before work began and supported throughout.

Wave 2.1 also established the technical and operational standards that would carry through every subsequent phase. All technologies across the borough use the same product specifications. That decision, taken early, is what makes the O&M programme so effective.

Wave 2.2

Wave 2.2 followed a similar routine, with the same technologies of air source heat pumps, solar PV, battery storage, and heating controls. These measures directly reduce what the council’s tenants pay to keep their homes warm and powered.

Carbon3’s in-house design team worked with the council’s housing and asset management teams to assess each property, model the appropriate measures, and produce designs that would hit EPC C as a minimum while accounting for the individual characteristics of each building. Where GBC wanted to go further, with additional measures, higher performance targets, technologies beyond what the funding covered, Carbon3 designed and delivered those too, funded directly by the council.

Resident engagement was a priority for Carbon3 from the first letter to the post-installation walkthrough. Appointments were made and rescheduled when residents weren’t available. Works were sequenced around how people actually live, particularly in sheltered housing where disruption carries a different weight. Vulnerable residents received additional support, and no work progressed in a home until the occupant understood what was happening and why.

Cleveland House: Retrofit Project of the Year shortlist 2026

Cleveland House is a sheltered housing scheme: 33 flats, many occupied by residents on fixed incomes, all of them more exposed to energy price volatility than the average household.

Carbon3 installed 86.57kWp of solar PV across the building. The technical approach that makes it significant is how that generation reaches residents. Rather than feeding into a communal supply or exporting to the grid, Carbon3 used direct current wiring to allocate 2.175kWp of solar capacity to each individual flat. Each home generates, consumes, and can export its own electricity through the Smart Export Guarantee. The savings are the resident’s, not the building’s.

This challenged standard practice in social housing retrofit. Communal solar is easier to install and simpler to administer. Flat-level allocation requires more careful design and more complex wiring. Carbon3 and Gravesham chose it because it would actually help the people living there.

The system has operated at 5% above anticipated generation since commissioning. Each flat produces close to 2,000kWh of clean electricity annually. Average resident savings are £400 a year. Smart meters in every flat give residents visibility of their own generation and give Carbon3 and GBC real-time performance data. If any system underperforms, an alert is sent automatically. As of early 2026, no faults have been reported.

A 22kW EV charger was installed at the scheme to support the council’s electric maintenance fleet on site visits, with preferential rates for residents set through Carbon3’s EV management app.

EPC ratings across the scheme improved from C to a high B. Annual emissions per flat fell to less than 0.3 tonnes which is a fraction of the national average.

“We thought this was going to be a difficult process, but Carbon3 were easy to get hold of, and told us what was going on. We’re now getting way smaller bills. I don’t wake up worried about whether I can afford to turn the heating on in winter anymore.” — Terry, resident at Cleveland House.

Chinnery Court: Innovation of the Year shortlist 2026

Chinnery Court applies the same flat-level solar principle with battery storage added — which changes what the technology can do for residents who spend most of their day at home.

62.1kWp of solar PV was installed, with 1.8kWp allocated to each flat via DC wiring. A separate 21.6kWp system serves communal infrastructure: automatic doors, stair lifts, lighting, heating, and laundry. Battery storage captures generation during daylight hours for use in the evening and overnight. In winter, when solar output is lower, batteries can be charged on cheaper overnight grid tariffs and discharged during peak rate hours; a direct fuel poverty intervention built into the system.

Smart storage heaters were specified individually following assessments of each resident’s needs and usage patterns. Communal system improvements deliver operational savings of over £5,000 a year for the council. Residents are reporting monthly savings of over £40.

Post-installation support was built into the programme. Carbon3 provided video guides for every technology installed, with subtitles for residents with hearing difficulties. A dedicated team lead maintained consistent contact throughout delivery. Apprentices working on site received additional briefings on operating in sensitive housing environments, and all resident feedback about the team was positive.

“I think you’ll find everyone is happy. The storage heaters are cheap to use, and we’ve definitely seen bill savings.” — Dave, resident at Chinnery Court.

The EV charger at Chinnery Court connects to Carbon3’s management app, giving Gravesham visibility of usage, the ability to set different tariffs by user group, and the option to offer residents preferential rates to support transition to electric vehicles.

The innovations developed at Chinnery Court, including flat-level DC solar allocation, battery storage as a fuel poverty tool, and unified monitoring across all technologies are now being rolled out across the Wave 3 programme. They emerged from the partnership with Gravesham’s clarity about what residents needed and Carbon3’s technical capability to build it.

Carl Ekman House

Carl Ekman House presented a different set of problems. A 14-storey residential tower near the Thames, with unique structural constraints and a recently replaced roof that carried a warranty Carbon3 could not compromise.

Carbon3 worked directly with the roofing manufacturer and the council’s asset management team to design a 24kWp solar and battery storage system that could be installed within the structural limits of the building, in a way that left the roof warranty intact. The system now operates at over 96% efficiency compared to design projections. There were no warranty issues, no disruption to residents during installation, and now a building that was previously without on-site renewable generation now has a working system that will run for decades.

Brookvale Depot

Brookvale is the council’s head office and the operational hub for its electric van fleet. Carbon3 installed 198kWp of solar PV, wired into the 12 EV chargers already in place on site. Read more about Brookvale Depot here.

Gravesham’s entire vehicle fleet is now electric. The solar charges those vehicles for free during the working day. What isn’t used for charging offsets the building’s electricity consumption, saving the council over £45,000 a year. Carbon3 manages the EV infrastructure through its own app platform, giving the council full visibility of charging usage, costs, and vehicle availability.

The fleet used to service all social properties in the borough are now 100% electric. Gravesham Borough Council lead by example.

Wave 3

Wave 3 is the largest phase of the programme and is currently underway. More than 420 additional homes are being retrofitted using the same delivery model, the same product specifications, and the same team that has been working with Gravesham since 2021. 100 properties have been decarbonised in the first year of this programme.

The consistency matters. An engineer visiting a Wave 3 property today is working with the same technologies they installed in Wave 2.1. When something needs attention, the team already knows the system, and any issues can be resolved straight away.

Where GBC has chosen to go beyond the funded measures, Carbon3 has designed and delivered those additional works under the same programme. The relationship between what the Warm Homes: Social Housing Fund covers and what Gravesham funds itself is managed through Carbon3 without the council needing to run a parallel procurement process.

The O&M programme

Renewable energy in social housing can fail without anyone noticing.

Gravesham did not allow that to happen. Carbon3 provides the full operations and maintenance programme across every asset installed across the borough, with real-time remote monitoring through Carbon3’s management portal, automatic alerts when performance drops below expected levels, and a dedicated O&M team that is entirely separate from the installation crews.

The O&M engineers are not the people who installed the systems and who are now called in when something goes wrong. They are a trained, dedicated team whose only job is keeping the systems running. They are cross-trained across all the technologies installed at Gravesham; solar PV, battery storage, heat pumps, EV chargers, so a single visit can address multiple systems in the same property. Every van carries a hospital kit: parts for every technology specification in use across the borough, chosen and standardised precisely so faults can be resolved on the first visit without ordering components or returning the following week and disrupting residents further.

Because Gravesham standardised on the same product specifications across all three funding waves, there are no legacy compatibility issues. The same parts work across the entire estate.

Resident complaints about heat pumps and solar are at their lowest since Carbon3 took over the O&M contract. That is not a soft metric. In occupied social housing with vulnerable tenants, a heat pump that fails in January or a solar system that stops offsetting bills can affect residents, especially vulnerable residents in sheltered housing schemes.

Learn how we consistently deliver the best O&M SLAs in the industry.

How the programme runs

Carbon3’s role across the Gravesham programme goes well beyond installation. Every aspect of delivery is managed directly; the surveys that establish what each property needs, the energy performance modelling that determines which measures will achieve EPC C and what it would take to go further, the system designs, the DNO applications and grid connection approvals, the sub-contractor procurement and management, the road closures where access requires them, the lodgement of completed works into the relevant compliance systems, and the resident engagement that runs from first contact through to post-installation support.

Gravesham Borough Council does not manage a supply chain across this programme. They only have to liaise with one team at Carbon3. Nothing gets lost this way, and quality is standardised.

Gravesham also upskilled their own team through the partnership. The council’s housing officers qualified as EPC assessors, enabling them to work alongside Carbon3’s design team on identifying and prioritising properties, combining Carbon3’s technical capability with the council’s knowledge of its own stock. That integration is part of why the programme has moved at the pace it has.

Carbon3 supported Gravesham through the funding application process across all three waves. Carbon3 helped develop project proposals, run feasibility surveys, and ensure that designs met the compliance requirements that grant funding demands.

The results

Across Waves 2.1, 2.2, and 3, Carbon3 has delivered more than 1,300kW of solar PV, 584kW of air source heat pumps, and over 30 EV charge points across the Gravesham estate, collectively offsetting close to 1,000 tonnes of carbon annually.

EPC A to C homes: up nearly 50%. D to G rated stock: down nearly 65%. Total carbon reduction from housing stock: 3,916 tonnes, a 28.6% fall. Fleet: 100% electric. Council ranking for social housing EPC performance: top ten nationally.

The programme has been shortlisted for three Unlock Net Zero awards: Retrofit Project of the Year for Cleveland House, Innovation of the Year for Chinnery Court, and Collaboration of the Year for the partnership as a whole.

Nicole Arthur, Head of Housing Assets at Gravesham Borough Council:

“Since 2021, we’ve worked with Carbon3 as our principal contractor for the installation and maintenance of renewable technologies across our social housing stock and council buildings. Carbon3 has delivered a range of successful projects including solar PV, air source heat pumps, battery storage, and EV charging installations across multiple sites. Their team also supported us in securing Wave 3 SHF financing, handling feasibility surveys, bespoke system designs, and installation with professionalism and efficiency. Carbon3’s approach to resident engagement and project delivery has been excellent. The results speak for themselves: across our portfolio, Carbon3’s systems are monitored in real time, achieving efficiencies of over 95% and delivering significant annual savings in both costs and carbon emissions. Resident complaints are at the lowest they have been since Carbon3 has taken over the O&M for ASHPs and solar. Carbon3 continues to provide our ongoing operations and maintenance service, ensuring our renewable assets remain in top condition and our residents continue to benefit. We value their expertise, reliability, and commitment to delivering long-term social value for our community.”

Gravesham set a net zero target and built a strategy around it. Carbon3 has been the partner making that strategy deliverable. For more than 5 years this partnership has been producing incredible results.

If you need to hit EPC targets by 2030, we can help you find funding and create a strategy to get you there. Don’t leave it too long, contact us today.