Our client manages residential estates across UK military sites, providing homes for service personnel and their families. These properties must deliver reliable heating and hot water whilst meeting increasingly strict energy efficiency and carbon reduction requirements.
Two separate estates required comprehensive heating system upgrades. At an estate in Bulford, existing air source heat pumps installed during construction were underperforming due to fundamental design and installation failures. At the same estate, properties relied on oil-fired heating systems, which are expensive to run, and carbon-intensive.
Both projects presented complex technical challenges requiring bespoke system design, and delivery across occupied family homes with minimal disruption to residents. Our client needed a contractor with both the technical capability to resolve underlying engineering problems and the operational expertise to manage large-scale programmes across sensitive defence estates.
Carbon3 was appointed to deliver complete heating system replacements across both sites, addressing equipment failures, system design flaws, and the transition from fossil fuel heating to low-carbon heat pump technology.
Project 1: 124 Homes – Failed ASHP Systems
During early surveys, it became clear that the original ASHP and underfloor heating (UFH) installations did not meet required standards. UFH loops were missing in several homes, and heat transfer was inconsistent across ground-floor zones.
Families were experiencing cold spots, unreliable heating, and higher-than-expected energy bills. Heat pumps were running constantly at inefficient flow temperatures, wearing components prematurely and failing to deliver the comfort and cost savings residents had been promised.
Several hot water cylinders were found to be incorrectly set up, meaning systems were unable to operate within their intended parameters.
This compounded efficiency losses and created intermittent hot water availability issues.
Carbon3’s initial investigation confirmed that replacing the existing heat pump units on a like-for-like basis would not resolve the deeper engineering and design problems. The underlying heating system design was flawed. A full-scale redesign was required to deliver a long-term, efficient, and reliable heating solution.
Project 2: 54 Homes – Oil Boiler Replacement
All 54 properties relied on oil-fired boilers for heating and hot water. Oil heating produces significantly higher carbon emissions than heat pumps, is expensive for residents to run (particularly during price volatility), and increasingly incompatible with government Net Zero targets and social housing decarbonisation requirements.
Existing Mechanical Ventilation with Heat Recovery (MVHR) units were not functioning correctly, creating poor indoor air quality and ventilation issues. These systems needed to be decommissioned and replaced with appropriate mechanical extract ventilation to maintain building regulation compliance.
Several properties required new Consumer Control Units (CCUs) to provide sufficient electrical capacity for heat pump installations. Existing infrastructure was not sized for the electrical demand of modern heating systems.
All works across both projects had to be delivered in occupied homes where residents include serving military personnel working irregular hours, families with young children, and households with specific access requirements. Disruption had to be minimised, communication had to be exemplary, and security protocols for defence estates had to be strictly observed.
Carbon3 delivered two comprehensive heating system replacement programmes, tailored to the specific technical requirements of each estate.
Project 1: Complete System Redesign
We completed full heat loss calculations for every property, allowing us to correctly size radiators and design revised heating circuits. In homes where underfloor heating performance could not deliver consistent heat, we transitioned properties to fully balanced radiator systems. This fundamental redesign addressed the root cause of system failures rather than simply replacing failed equipment.
We installed Mitsubishi 8.5 kW air source heat pumps paired with new 250L pre-plumbed cylinders. All systems were configured to operate within optimal temperature ranges (typically 45-50°C flow temperature for radiator systems), improving energy efficiency, reducing wear on components, and delivering consistent heating performance.
Each property was fitted with a remote management platform that allows our client to diagnose issues remotely, monitor system performance in real time, control heating and hot water in void properties, and track running costs and system trends. This digital layer reduces reactive maintenance visits and improves asset visibility across the estate.
Project 2: Oil to ASHP Conversion
All 54 homes transitioned from oil-fired boilers to air source heat pumps. This required removal of existing oil boilers, oil tank decommissioning (where applicable), installation of new heat pumps and hot water cylinders, and complete heating system commissioning.
Each property received full heat loss calculations to ensure correctly sized heat pumps and appropriate emitter upgrades (radiators) where required to operate efficiently at lower flow temperatures than oil boilers. Existing Mechanical Ventilation with Heat Recovery (MVHR) units were decommissioned across all properties. To maintain Building Regulations compliance following MVHR removal, we installed new mechanical extract fans to kitchens, utilities, WCs, ensuites, and bathrooms. This ensured adequate ventilation rates whilst removing the complexity and maintenance burden of whole-house MVHR systems.
Selected properties required replacement Consumer Control Units (CCUs) to provide sufficient electrical capacity for heat pump operation. Our electricians upgraded distribution boards where existing infrastructure was inadequate, ensuring safe and compliant installations.
All works across both projects were carried out by Carbon3’s directly employed Mitsubishi-trained and approved engineers. Evidence of training certification and manufacturer approvals was provided to our client prior to commencement, ensuring compliance with contract requirements and manufacturer warranty terms.
Close coordination with residents ensured minimal disruption to family life. We provided clear communication about timelines, scheduled appointments around work and school commitments, and maintained dedicated liaison support throughout delivery.
Our project management team worked closely with the client to align delivery with defence estate security requirements, access protocols, and operational constraints.
Project 1 Results:
By redesigning the heating system, rebalancing heating circuits, and installing correctly sized equipment, running costs have been reduced by an estimated 20-30% compared to the failed original installations. Residents now benefit from predictable, affordable heating costs.
Properly functioning heat pump systems with optimised controls have improved Energy Performance Certificate ratings across the estate, supporting the client’s compliance with energy efficiency requirements for social housing. The 124 upgraded ASHPs are estimated to reduce carbon emissions by approximately 212 tonnes CO₂ per year compared to the baseline of poorly performing systems, based on typical household heat demand and a seasonal performance factor of 3.0.
Project 2 Results:
Converting 54 homes from oil heating to air source heat pumps delivers substantial carbon savings of an estimated 256.5 tonnes CO₂/year, which is an 80% reduction in heating-related carbon emissions. Residents are now looking to save an estimated £400-£600 per year on heating costs, protecting families from oil price volatility.
Client Testimonial:
The Project Manager for the site in Bulford had this to say after the projects were completed:
“The transition to air source heat pumps on the Canadian Estate in Bulford has significantly improved the quality of life in by providing a consistent, controllable ambient temperature throughout the year. Unlike older systems, these units operate with high energy efficiency, helping to shield service families from fluctuating fuel costs while ensuring a warm, damp-free living environment. Carbon 3s knowledge and support of these renewable systems has been a breath of fresh air. Thank you”
Combined Impact Across Both Projects (178 Homes)
- Total annual carbon reduction: 468.5 tonnes CO₂/year
- Estimated £100,000+ annually across the estate in reduced heating costs
- 178 homes upgraded to low-carbon heating with improved EPC ratings
- Remote monitoring and proactive maintenance contracts reduce reactive callouts, emergency repairs, and resident dissatisfaction
- Mitsubishi-approved installations ensure full manufacturer warranty coverage across all heat pump equipment
