Whole-House Energy Retrofit
Insulation, heat pump, underfloor heating, solar, battery, and ventilation. One company, one project plan, one point of contact. The complete fabric-first approach to slashing your energy bills by up to 80%.
The Fabric-First Approach
Most installers sell individual products. A solar company sells you solar. A plumber sells you a heat pump. Nobody looks at the whole picture. The result is oversized equipment, wasted money, and performance gaps.
Green Hat Renewables takes a different approach. With roots in construction and expertise across all five core building services, we design your retrofit as a single, coordinated project. Every element is sized and sequenced to complement the others, delivering the lowest possible energy bills with the highest possible comfort.
The Five Steps to a Zero-Carbon Home
Insulate the Envelope
Up to 70% heat loss reductionExternal wall insulation reduces heat loss by up to 70% in solid-walled homes common across East Anglia. By wrapping your home first, every subsequent system works more efficiently and can be sized smaller, saving you money.
Learn more about External Wall InsulationUpgrade the Heating
£7,500 BUS grant availableWith insulation in place, a smaller heat pump delivers the same comfort at lower running costs. The £7,500 BUS grant makes the switch affordable, and a well-insulated home means the heat pump operates at peak efficiency year-round.
Learn more about Air Source Heat PumpDistribute Efficiently
25% more efficient than radiatorsUnderfloor heating operates at 35-45 degrees C, precisely where heat pumps are most efficient. The result is even warmth throughout your home with no cold spots and no radiators taking up wall space.
Learn more about Underfloor HeatingGenerate Your Own Power
60-80% heat pump electricity offsetSolar panels offset the electricity your heat pump consumes. Paired with battery storage, you store daytime generation for evening use and earn from smart export tariffs. A 4kW system typically covers 60-80% of a heat pump's annual electricity needs.
Learn more about Solar Panels + BatteryVentilate Properly
95% heat recovery from exhaust airAn airtight, insulated home needs controlled ventilation to maintain fresh air quality. MVHR recovers up to 95% of the heat from extracted air, delivering fresh filtered air without the energy penalty of opening windows.
Learn more about MVHRIndicative Costs and Grants
Every retrofit is different. These ranges are based on a typical 3-bed detached home in East Anglia. Your free survey will provide exact figures.
| Component | Cost Range | Available Grant / Relief |
|---|---|---|
| External Wall Insulation | £5,000-£15,000 | ECO4 may cover full cost |
| Air Source Heat Pump | £10,000-£18,000 | £7,500 BUS grant |
| Underfloor Heating | £4,000-£7,000 | Included in BUS quote |
| Solar Panels (4kW) | £5,000-£8,000 | 0% VAT |
| Battery Storage (5kWh) | £2,500-£5,000 | 0% VAT |
| MVHR System | £4,000-£8,000 | Part of retrofit coord. |
| Total before grants | £30,500-£61,000 | £7,500+ in grants |
Phased Payment, Not Lump Sum
Most homeowners spread their retrofit over 6-24 months. You pay for each phase as it happens, not the full amount upfront. We also offer finance options on individual elements. Start with insulation and a heat pump (net cost from £7,500 after BUS grant), then add solar and battery when ready.
Why One Company Matters
One person coordinates every trade, every delivery, every inspection. No chasing multiple contractors.
We size your heat pump based on the insulated building, not the current one. Smaller pump, lower cost, better efficiency.
If anything goes wrong with any element of your system, you call one number. No finger-pointing between trades.
15+ years in construction means we understand building fabric. We do not just bolt renewables onto walls, we understand the walls themselves.
We apply for BUS, check ECO4 eligibility, ensure 0% VAT, and explore local authority funding. All paperwork handled.
Every phase is designed with the complete system in mind. Nothing gets ripped out or replaced when the next phase begins.
Typical Retrofit Timeline
Frequently Asked Questions
What is a whole-house retrofit?
A whole-house retrofit is a coordinated approach to improving your home's energy performance by addressing insulation, heating, ventilation, and renewable energy generation together. Rather than treating each upgrade in isolation, the fabric-first approach ensures each system is optimised to work with the others, delivering greater comfort, lower bills, and significantly reduced carbon emissions.
Why does the order of installation matter?
The fabric-first principle means insulating your home before upgrading heating systems. By reducing heat loss first, you need a smaller, cheaper heat pump. The underfloor heating then distributes warmth efficiently at the low temperatures heat pumps prefer. Solar and battery address the remaining electricity cost, and MVHR ensures air quality in the newly airtight home. Done in the wrong order, you end up with oversized equipment and higher costs.
How much does a whole-house retrofit cost?
A complete retrofit typically costs £30,000-£60,000 before grants. After the £7,500 BUS grant, 0% VAT on solar and battery, and potential ECO4 funding for insulation, the net cost ranges from £15,000-£40,000 depending on property size and scope. The annual savings of £1,500-£1,800 give a payback period of 10-20 years, but you also gain comfort, property value, and future-proofing against energy price rises.
Can I do a whole-house retrofit in stages?
Yes, and many homeowners do. We recommend starting with insulation (the foundation), then adding a heat pump (the biggest running-cost saving), followed by solar, battery, and MVHR as budget allows. We design each stage with the complete system in mind, so nothing needs replacing later. We provide a full retrofit plan upfront with a phased installation timeline.
Do I need all five services for a retrofit?
Not necessarily. The core of a retrofit is insulation plus an efficient heating system (heat pump with underfloor heating or upgraded radiators). Solar and battery significantly reduce electricity costs. MVHR is most important in well-sealed homes. During your free survey, we assess which combination delivers the best return for your specific property and budget.
What grants are available for a whole-house retrofit?
Multiple grants can be combined: the Boiler Upgrade Scheme provides £7,500 towards a heat pump, 0% VAT applies to solar panels and battery storage until March 2027, and the ECO4 scheme may fund insulation for eligible households. Some local authorities in Cambridgeshire, Norfolk, and Suffolk also offer retrofit grants. We check all eligibility during your free survey and handle all applications.
How long does a complete retrofit take?
A phased retrofit typically takes 2-4 months from start to finish. External wall insulation takes 1-3 weeks, the heat pump and underfloor heating 1-2 weeks, solar and battery 1-2 days, and MVHR 2-3 days. We coordinate all trades to minimise disruption and can schedule around your household routine.
Why choose Green Hat for a whole-house retrofit?
Green Hat Renewables is one of very few companies in East Anglia that delivers every element of a whole-house retrofit in-house. Our construction heritage means we understand building fabric, and our MCS certification covers both renewable heating and generation. One company, one project manager, one warranty. No subcontractor coordination, no finger-pointing, and no gaps between services.
Related Guides
Learn about costs, grants, and the technology behind each element of a whole-house retrofit.
Ready to Switch to Clean Energy?
Get your free, no-obligation survey and personalised quote. Our MCS-certified team is ready to help you save money and reduce your carbon footprint.