What is a deep retrofit?
A deep retrofit is a whole-house energy upgrade that transforms your home’s performance from the fabric out. Rather than doing one upgrade at a time, say, just insulation or just a heat pump, a deep retrofit addresses everything together: insulation, heating system, ventilation, windows, and often solar panels.
The goal is to achieve a BER rating of B2 or better, which means your home will use dramatically less energy to stay warm and comfortable. A typical Irish home rated D or E before retrofit will jump to A2 or A3 after a deep retrofit, cutting energy use by 60–80%.
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Deep retrofits are typically carried out through the SEAI One Stop Shop (OSS) service, where a single registered provider manages the entire project from start to finish, including applying for all grants on your behalf and deducting them from the cost upfront.
One Stop Shop vs individual grants
There are two main routes to upgrading your home through SEAI:
One Stop Shop (Deep Retrofit)
- Single provider manages everything
- Grants deducted upfront from your bill
- Must achieve BER B2 or better
- Multiple upgrades done together
- Can provide up to 50% of total project cost
- Post-works BER assessment included
- Home must be built before 2011
- 31 registered providers nationwide
Individual Grants (Step-by-Step)
- You manage each upgrade separately
- Pay upfront, claim grant back after
- No minimum BER target required
- Do one upgrade at a time, at your pace
- Fixed grant per measure
- Good for phased approach on a budget
- Home must be built before 2011
- Choose your own SEAI-registered contractors
For larger projects (typically €40,000–€60,000+), the One Stop Shop route is usually more generous because the 50% grant can exceed what you’d get stacking individual grants. It’s also far less hassle, one provider, one project, one bill. For smaller budgets or if you only need one or two upgrades, the individual grants route gives you more flexibility to upgrade at your own pace.
How much does a deep retrofit cost?
A typical whole-house deep retrofit in Ireland costs €50,000–€75,000 before grants, depending on your home’s size, condition, and the upgrades needed. After SEAI grants of €25,000–€35,000+, the net cost to the homeowner is typically €25,000–€48,000.
| Home Type | Typical Cost (Before Grants) | Typical Grant | Net Cost to You |
|---|---|---|---|
| Mid-terrace (3 bed) | €35,000 – €50,000 | €18,000 – €25,000 | €17,000 – €30,000 |
| Semi-detached (3 bed) | €45,000 – €65,000 | €25,000 – €32,000 | €22,000 – €38,000 |
| Detached (4 bed) | €60,000 – €85,000 | €30,000 – €40,000 | €30,000 – €50,000 |
| Bungalow | €45,000 – €70,000 | €25,000 – €35,000 | €22,000 – €40,000 |
Costs vary widely depending on the current condition of your home, its age, the specific upgrades required, and your location. Always get at least three quotes from registered One Stop Shops.
1970s semi-detached, South Dublin
A typical 3-bed semi built in the 1970s with original single-glazed windows, no wall insulation, and an oil boiler. The deep retrofit included external wall insulation, attic insulation, triple-glazed windows, an air-to-water heat pump with new radiators, mechanical ventilation, and a 4kWp solar PV system.
SEAI grants available for retrofit (2026)
When you go through the One Stop Shop route, your provider will claim all applicable grants and deduct them from your bill. Here are the individual measures and their grant values:
| Upgrade Measure | Semi-D Grant | Detached Grant | Notes |
|---|---|---|---|
| Attic insulation | €1,300 | €2,000 | Increased from Feb 2026 |
| Cavity wall insulation | €1,200 | €1,800 | Increased from Feb 2026 |
| External wall insulation | €6,000 | €8,000 | |
| Internal wall insulation | €4,500 | €4,500 | |
| Heat pump system | €12,500 | €12,500 | New combined rate 2026 |
| Heating controls | €700 | €700 | |
| Windows | €3,000 | €4,000 | New standalone grant 2026 |
| Doors (max 2) | €1,600 | €1,600 | €800 per door |
| Solar PV (up to 4kWp) | €1,800 | €1,800 | 0% VAT on supply & install |
| Solar thermal | €1,200 | €1,200 | |
| Mechanical ventilation (MVHR) | €1,500 | €1,500 |
With the One Stop Shop route, you never pay the full cost. Your provider claims the grants directly from SEAI and deducts them from your invoice, so you only pay the balance. This is a major advantage over the individual grants route where you typically pay first and claim back later.
How the One Stop Shop process works
The beauty of the One Stop Shop is that it’s as hands-off as possible for you. Here’s the typical journey:
Before contacting any One Stop Shop, get an independent BER assessment. This tells you your current rating, confirms whether your home qualifies for the OSS route (B3 or lower required), and gives you a clear picture of what upgrades are needed, so when providers quote you, you can compare like-for-like. Book a BER with Homerating.ie →
1. Get a BER assessment
An independent BER assessment confirms your current rating and whether you qualify for the One Stop Shop (B3 or lower required). The Advisory Report identifies where your home is losing energy and which upgrades will deliver the best results. This is your roadmap. Book with Homerating.ie →
2. Contact registered One Stop Shops
Armed with your BER report, approach at least 3 of the 31 SEAI-registered providers. They’ll arrange a consultation and can give you more accurate quotes because you already know your starting point.
3. Home energy assessment & retrofit plan
Your chosen provider carries out their own detailed assessment and designs a tailored retrofit plan showing exactly which upgrades are recommended, the total cost, all applicable SEAI grants, and the net price you’ll pay.
4. Grant application
Your One Stop Shop handles the entire SEAI grant application on your behalf. You don’t need to deal with SEAI paperwork, this is all managed for you.
5. Works carried out
The retrofit works are completed, typically over 4–8 weeks depending on the scope. Your provider coordinates all the different trades, insulators, plumbers, electricians, window fitters, so you deal with one point of contact.
6. Post-works BER assessment
A new BER assessment confirms your home has reached B2 or better. This is carried out by your provider and included in the project.
7. Enjoy your upgraded home
Your home is warmer, quieter, and cheaper to run. Most homeowners report dramatically better comfort, lower bills, and an end to draughts and cold spots from day one.
Who’s eligible for the One Stop Shop?
The One Stop Shop service is available to:
- Homeowners whose property was built and occupied before 2011
- Landlords of rental properties meeting the same criteria
- Approved Housing Bodies (AHBs)
Your home must also:
- Have a current BER of B3 or lower before works begin (this requirement is being relaxed from March 2026)
- Achieve a minimum BER of B2 or better after the retrofit
- Not have previously received SEAI grants for the same measures
From March 2026, the requirement to achieve a minimum energy improvement of 100 kWh/m²/year is being removed where a heat pump is installed. This makes it easier for homes that are already partially upgraded to qualify for the One Stop Shop route.
Special eligibility: landlords
Landlords can access the One Stop Shop for rental properties. On top of the SEAI grants, landlords can deduct the lesser of €10,000 or the actual amount spent (net of grant) from their rental income for tax purposes. From 2026, this applies to up to three properties (increased from two). The tax relief covers works carried out between 2023 and 2028.
Financing your retrofit
Even after grants, a deep retrofit is a significant investment. Here are the main ways to finance the balance:
Home Energy Upgrade Loan Scheme
The government-backed loan scheme lets homeowners borrow €5,000–€75,000 at rates starting from 2.99%. well below standard personal loan rates. The loan must be used alongside an SEAI grant and achieve at least a 20% improvement in energy performance.
Participating lenders include PTSB, AIB, Bank of Ireland, Avant Money (via An Post), and several credit unions through the Irish League of Credit Unions.
Other financing options
- Credit union loans. Many credit unions offer competitive rates for home improvement, typically 5–7%
- Home equity. If you have significant equity in your home, remortgaging or a top-up mortgage may offer the lowest rates
- One Stop Shop financing. Some providers have partnered with finance companies to offer financing directly as part of the retrofit package
A deep retrofit typically saves €1,500–€3,000+ per year on energy bills. If you finance the balance over 10–15 years, the monthly loan repayment is often less than your previous energy bill, meaning the upgrade effectively pays for itself from day one.
What’s new for retrofits in 2026
The National Residential Retrofit Plan 2026 brought the most significant changes to retrofit grants in years:
- Heat pump grant increased to €12,500. combines the heat pump (€6,500), radiator and pipework upgrades (€2,000), and a new renewable heating bonus (€4,000)
- New standalone windows & doors grants. up to €4,000 for windows and €1,600 for doors without a full retrofit, provided your home meets fabric performance standards
- Increased insulation grants. attic and cavity wall insulation grants increased from February 2026
- Relaxed OSS eligibility. the 100 kWh/m²/year minimum improvement requirement removed where a heat pump is installed
- Second wall insulation. homeowners who previously received a wall insulation grant can now apply for a second wall measure
- First-time buyer bonus. enhanced attic insulation grants, often covering most or all of the cost
- Higher welfare grants. homeowners on qualifying welfare payments get higher fixed grants for attic and cavity wall insulation
- Total budget of €558 million targeting 70,000 homes
Finding a One Stop Shop provider
There are currently 31 SEAI-registered One Stop Shop providers operating across Ireland. Some operate nationally, others serve specific regions. Major providers include Bord Gáis Energy, Electric Ireland, SSE Airtricity, and specialist firms like Kore Retrofit, Retrofit Design, Greenwatt, and Ohk Energy.
How to choose the right provider
- Verify SEAI registration. always confirm the provider is currently registered on SEAI’s official list
- Get at least 3 quotes. scope of works, timeline, and net cost can vary widely
- Ask for references. request before-and-after BER certificates from completed projects similar to yours
- Check their coverage. not all providers serve all counties
- Understand what’s included. confirm the grant is deducted upfront and a minimum BER improvement is guaranteed
Before committing to a deep retrofit, it helps to know your current BER rating. A BER assessment from Homerating.ie will tell you exactly where your home stands and help you understand the potential for improvement. Read our BER guide →
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This guide is maintained by HomeEnergyGuide.ie, an independent resource by Homerating.ie. We are not a One Stop Shop or retrofit contractor, our recommendations are independent and based on verified data from SEAI, ESRI, and industry sources. All grant figures verified against seai.ie. Last verified: March 2026.