Quick answer: A BER rates a home's energy efficiency on the simplified A0–G scale (from 24 May 2026). A0 is the top band — fossil-fuel-free, near-zero energy. G is the lowest. All new builds must achieve at least A under current regulations. An A-rated home costs significantly less to heat and may qualify for a lower "green mortgage" rate.
A BER (Building Energy Rating) is an energy efficiency certificate for a property, similar to the energy label on household appliances.
From 24 May 2026 all new BER certificates issued by SEAI use a simplified eight-band scale. Certificates issued before 24 May 2026 remain valid for their 10-year lifespan and continue to use the legacy A1–G sub-band scale — see the historic table below.
BER Scale (from 24 May 2026)
| Rating | Description |
|---|---|
| A0 | Highest efficiency — fossil-fuel-free, nearly zero energy (net zero or better) |
| A | Excellent — very low energy, heat pump standard |
| B | Good — well-insulated, low running costs |
| C | Moderate — typical of homes built late 1990s–2010s |
| D | Below average — higher running costs, older stock |
| E | Poor — significant energy use |
| F | Very inefficient |
| G | Lowest — uninsulated older property |
Historic certificates (issued before 24 May 2026)
Properties with a BER certificate issued before 24 May 2026 continue to show the legacy A1–G sub-band scale. These certificates remain valid for their 10-year lifespan. When comparing properties, both certificate types are acceptable to lenders and for legal compliance.
| Rating | Description |
|---|---|
| A1 | Highest — nearly zero energy |
| A2 | Excellent — modern passive house standard |
| A3 | Very good — well-insulated new build |
| B1 | Good — above average |
| B2 | Average for modern builds |
| B3 | Below average |
| C1–C3 | Moderate — typical 1970s–2000s homes |
| D1–D2 | Poor — high energy costs |
| E1–E2 | Very poor |
| F | Very inefficient |
| G | Lowest — uninsulated older property |
How It's Calculated
A BER assessor visits the property and assesses: - Wall, roof, and floor insulation levels - Window and door glazing (single, double, triple) - Heating system type and age (gas, oil, heat pump, etc.) - Hot water system - Ventilation - Renewable energy sources (solar panels, etc.)
The result is expressed in kWh/m²/year of primary energy — the BER letter corresponds to a band within this scale.
Why It Matters
Running costs: An A-rated home uses a fraction of the energy of a D or E-rated home. Heating and electricity bills can be significantly lower.
Mortgage and grants: Some lenders offer preferential "green mortgage" rates for A or B rated properties. SEAI grants for retrofitting are available to upgrade lower-rated homes.
New builds: All new builds in Ireland must achieve at least A under current building regulations (previously A2 on the legacy scale). Most recent new builds achieve A or better.
Older homes: Pre-1980 homes are often C, D, or E rated. A full retrofit (insulation, heat pump, windows) can cost €20,000–€60,000 but may qualify for SEAI grants.
SEAI Grants for Retrofitting
The SEAI (Sustainable Energy Authority of Ireland) offers grants for upgrading existing homes. The following figures reflect the February 2026 uplift (SEAI grant announcement):
| Upgrade | SEAI Grant |
|---|---|
| Heat pump installation | Up to €12,500 |
| Attic insulation | Up to €1,500 (up to €2,500 for eligible first-time buyers) |
| Cavity wall insulation | Up to €1,800 |
| External wall insulation (detached) | Up to €8,000 |
| External wall insulation (semi-detached) | Up to €6,000 |
| External wall insulation (mid-terrace) | Up to €3,500 |
| External wall insulation (apartment) | Up to €3,000 |
| Windows | €1,500–€4,000 (varies by dwelling type) |
| External doors | €800 per door (up to 2 doors, max €1,600) |
| Solar PV panels | Up to €1,800 |
| Mechanical ventilation (MVHR) | Up to €1,500 |
The One Stop Shop scheme through SEAI also offers a coordinated retrofit service for homeowners upgrading multiple elements at once, including a project coordinator and a guaranteed BER improvement. There is no fixed cap on total grant support under the One Stop Shop — grants are applied per measure as above.
Always check seai.ie/grants for current amounts, as grant levels are reviewed periodically.
Checking a BER
Every property listed for sale or rent must have a valid BER certificate. You can verify any BER certificate on the SEAI National BER Register using the property address or BER number.
Key Points
- A BER is valid for 10 years unless significant changes are made to the property.
- A BER must be provided to a buyer or tenant — it is a legal requirement.
- The BER reflects the building's potential, not the current occupant's behaviour.
Common Questions
Q: Does a high BER rating affect my mortgage rate? Yes — some Irish lenders offer "green mortgage" rates for A-rated homes (A or A0 on the new scale; A1–A3 on older certificates) that are 0.1–0.3% lower than standard rates. Ask your mortgage broker whether the property you're buying qualifies.
Q: How much does it cost to improve a BER rating? Individual upgrades can be affordable with SEAI grants: attic insulation with a €1,500 grant can move a D-rated home to C. A full whole-house retrofit (insulation, heat pump, windows) typically costs €30,000–€60,000 before grants — the heat pump grant alone is now €12,500, and the SEAI One Stop Shop coordinates the full suite of eligible grants with no fixed cap on total support.
Q: Is a BER certificate required when selling or renting a property? Yes — having a valid BER certificate is a legal requirement when listing a property for sale or rent. It must be included in all advertising. Certificates are valid for 10 years unless significant modifications are made.