Heat Pump, Solar PV and Battery Retrofit for Armed Forces Sheltered Housing
Client: E.ON / Haig Housing
Location: South East England
Sector: Residential / Social Housing
Services: Heat Pump Design & Installation, Solar PV Design & Installation, Battery Storage, EPC Assessment, Retrofit Assessment, Planning Support
Technology: Air Source Heat Pumps, Allume SolShare, Sunamp Thermal Storage, Communal Battery Storage
Partners: Haig Housing, E.ON, DJB Installations, Wolseley, Trianco, Sunamp, Midsummer Energ
Project Summary
Flint Energy delivered a comprehensive whole-house retrofit across 12 sheltered accommodation units managed by Haig Housing, a housing association providing homes for veterans and armed forces families.
Working from concept through to completion, Flint replaced outdated night storage heaters and immersion hot water systems with modern air source heat pumps, Sunamp thermal storage and a communal solar PV and battery system - transforming cold, expensive-to-heat homes into warm, energy-efficient properties that residents are now actually using their heating in.
The project upgraded EPC ratings from D and E to B across all 12 units, significantly reduced resident energy bills and gave Haig Housing a working blueprint for upgrading the rest of their housing stock.
The Challenge
Many residents at the scheme had been avoiding using their heating altogether because of the cost. Night storage heaters are notoriously difficult to control - they charge overnight on off-peak electricity and release heat throughout the day, regardless of whether residents are in or want warmth. For older residents on fixed incomes, the result was a difficult choice between warmth and affordability.
Haig Housing wanted to address this, but with a constrained budget. They needed a partner who could design and deliver a meaningful upgrade without overrunning costs, and who could use the project as a replicable model for upgrading their wider stock.
The specific challenges were:
Replacing inefficient night storage heaters with a system residents could actually control
Improving hot water provision, which had previously relied on immersion heaters
Maximising the impact of a limited budget through smart technology integration
Managing a live installation across 12 occupied homes with minimum disruption to residents
Obtaining planning permission for the works
Helix Energy’s Solution
Helix Energy supported Haig Housing from the earliest stages, carrying out a full range of surveys before a single system was specified.
Initial assessments included RdSAP surveys, retrofit assessments, improvement option evaluations, heat loss calculations and solar design surveys - ensuring every technology decision was grounded in the actual performance characteristics of the buildings.
12 Air Source Heat Pumps (Trianco)
Each flat received a new air source heat pump, replacing the night storage heaters with a modern, responsive radiator heating system that residents can control room by room. For the first time, residents could turn the heating on when they needed it and off when they did not.
New Central Heating and Hot Water Systems
Each flat received a fully new central heating system with radiators and a new hot water system connected to Sunamp thermal storage units. Sunamp batteries store heat generated by the ASHP, providing fast-recovery hot water with significantly reduced standing losses and improved temperature stability.
Communal Solar PV with Allume SolShare
A communal rooftop solar PV array was installed and connected via Allume's SolShare system, distributing solar-generated electricity in real time across all 12 flats. Rather than generating power that goes unused or is exported at a low rate, SolShare directs solar energy to wherever demand exists in the building at any given moment, increasing on-site self-consumption significantly.
Communal Battery Storage
A communal battery system was integrated to capture excess solar generation during the day and make it available to residents in the evening, reducing reliance on peak-tariff grid electricity.
Planning and Resident Liaison
Helix Energy managed the planning application process for the heat pump installations and maintained close communication with residents throughout the works — an essential part of delivering a retrofit programme in occupied sheltered accommodation.
Key Deliverables
✓ 12 air source heat pump installations
✓ New central heating system to each flat
✓ New hot water system with Sunamp thermal storage to each flat
✓ Communal solar PV array with Allume SolShare distribution
✓ Communal battery storage system
✓ Full planning permission obtained
✓ Resident liaison throughout installation
✓ Complete retrofit assessments, RdSAP surveys and heat loss calculations
✓ Full commissioning, testing and handover documentationr
Results & Impact
EPC Ratings Transformed
All 12 properties were upgraded from EPC D and E ratings to B, representing a substantial improvement in energy performance and long-term asset value for Haig Housing.
Residents Using Their Heating Again
Most residents had not been turning their heating on before the retrofit due to the cost and the unpredictable nature of night storage heaters. With responsive radiator heating and controllable ASHP systems, residents now have warm homes they can manage on their own terms.
Reduced Energy Bills
Transitioning from high-tariff electric storage heating to an efficient heat pump system, combined with on-site solar generation and battery storage, has significantly reduced energy costs for residents. The SolShare system ensures solar generation is used on-site rather than exported, and the battery captures daytime generation for evening use when residents are most likely to need it.
Carbon Reduction
The replacement of all-electric storage heating with heat pumps, solar PV and battery storage has significantly reduced carbon emissions across the scheme, supporting Haig Housing's decarbonisation commitments.
A Blueprint for Future Upgrades
Haig Housing commissioned this project specifically to understand how their housing stock could be improved at scale. Helix Energy's approach - integrating heat pumps, solar, battery and thermal storage within a constrained budget — provides a clear and replicable model for future schemes across their portfolio.
Programme Delivered on Budget
The full retrofit was delivered within the agreed project scope, coordinating works across heating, hot water, solar and battery systems while managing access challenges and legacy installation constraints in occupied properties.
Why This Project Matters
This project is about more than technology. It is about people - veterans and armed forces families who were living in cold homes because their heating systems were too expensive and too confusing to use.
By combining heat pumps, solar sharing and battery storage in a holistic retrofit, Helix Energy delivered warmth, affordability and energy security to residents who needed it most, while giving their landlord a practical, costed model for doing the same across their wider portfolio.
That is what integrated energy design looks like in practice.
Interested in a Similar Project?
Whether you manage sheltered accommodation, social housing or a portfolio of residential properties, Helix Energy can assess your stock and develop a retrofit strategy that improves EPC ratings, reduces resident bills and works within your budget.