How to boost your Building Energy Rating (BER)
Boosting your home’s energy rating can slash your energy bills, make your house warmer and even unlock cheaper mortgage deals. Here’s how to improve your BER and save money.
Latest UpdateBER system to be overhauled from 24 May under new EU rules
24/04/2026: Ireland’s Building Energy Rating (BER) system will be overhauled from 24 May, with the current 15-point A-G scale simplified to a new A-G rating system under EU rules.
Existing BER certificates will remain valid for 10 years, so most homeowners won’t be affected until they need a new certificate, for example when selling or renting their property.
A small number of less energy-efficient homes in the D, E, F and G categories could see their rating change under the new system, particularly if they are close to the boundary between two bands.
The new scale will also introduce an A0 rating for zero-emissions homes that use very little energy, produce very low greenhouse gas emissions and have no fossil fuel boilers on site.
What is a Building Energy Rating (BER)?
A Building Energy Rating (BER) shows the energy performance of your home and grades your home’s energy efficiency on a scale of A-G.
A-rated homes are most energy-efficient and G-rated homes are the least. The higher your BER, the lower your energy use is; for instance, an A-rated house conserves heat better so less fuel is needed to keep it warm.
When it comes to energy bills, an A-rated home will benefit from lower energy costs, whereas a G-rated home will attract high energy bills.
The BER certificate
A BER certificate is required for the majority of homes for sale or rent in Ireland and BER details must be included in advertisements when a home is on the market.
Since 2007 all new homes are required to have a BER certificate. It ensures new dwellings are built with energy-efficient designs, materials, and appliances in line with the Government’s Sustainable Energy Policy.
How do I get a copy of my BER?
Find if your home has a BER, and download the certificate and advisory report on the SEAI National BER Register. You’ll need the MPRN number from an electricity bill and the BER number.
Why is it required?
An owner must provide a BER to prospective buyers or tenants when a home is offered for sale or rent and homeowners must obtain a BER before a new home is occupied for the first time.
A BER is required on a dwelling when it is:
- Offered for sale off plans (provisional BER)
- A new dwelling for occupation
- Offered for sale or rent
- Undergoing work that requires a grant from SEAI
Exemptions apply to protected, historic structures and temporary or derelict properties.
How do you get a BER?
BERs are carried out by independent assessors registered with the Sustainable Energy Authority of Ireland (SEAI). The assessor will need between 30 minutes and an hour to do the inspection depending on the size of your home.
You can find a list of registered BER assessors at SEAI.ie. Just search in your area or check if an assessor is registered.
Finding a BER assessor
Using the SEAI’s BER assessor tool, shop around, get multiple quotes (at least three) and compare prices and information.
When dealing with assessors:
When you’ve chosen an assessor:
- Request a written agreement or contract (SEAI example here)
- Request a description of proposed services, costs and expenses
- Confirm your postal address and Eircode
- Confirm your Meter Point Reference Number (MPRN) from your electricity bill
Before the assessment begins:
- Ensure any planned home improvements are complete
- Confirm documentation checklist (below)
BER Checklist
Having the right documents at hand can ensure an accurate BER reading.
If you can, provide information on:
Readying your home can also help the process go smoothly. Ensure:
- All areas are unlocked and accessible (e.g. attic, outdoor buildings and/or garage)
- All areas in your home that have been extended or upgraded are clearly marked
- You identify the heating system and heating controls
- Check if the documentation you have provided is sufficient
If you can’t provide some relevant documents, the BER assessor will use ‘default values’ or estimates, which could result in your home receiving a lower BER rating.
How long is a BER certificate valid?
A BER certificate is valid for 10 years provided there’s no change to your home that could affect the energy performance.
For unbuilt homes, a Provisional BER based on plans for your home is only valid for 2 years.
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How much does a BER certificate cost?
There is no set fee for a BER certificate so it’s wise to shop around to get the best price.
A typical home or an apartment of 1,200 sq could cost around €150 while a large house, duplex, or penthouse could cost between €200 and €300*.
Make sure you get written quotes before commissioning a BER assessment and check the following:
- Is the assessor insured and registered
- Is the price quoted inclusive of the SEAI Registration Charge
- Does the price include VAT
*Cost depends on property size, complexity, location, and quotes from assessors.
How BER affects energy efficiency
Ireland’s Building Energy Rating (BER) shows how efficiently a home uses energy for heating, hot water and lighting.
Homes with a higher BER are better insulated and need less energy to stay warm - meaning lower running costs and fewer carbon emissions.
The table below compares the relative efficiency of each BER grade to an A1-rated home.
For example, a C3-rated home uses roughly seven times more energy than an A1 home, so it retains only around one-seventh of the heat under the same conditions.
| BER grade | Relative efficiency (vs A1) | Example home / what it means in practice | |
|---|---|---|---|
| A1 | 100% | Very low running costs; highly efficient, near zero-energy building (NZEB) | |
| A3 | 56% | Excellent efficiency; most new urban homes with solar panels | |
| B1 | 30% | Efficient, modern home with upgrades | |
| B3 | 23% | Retrofitted or modern property; meets SEAI B2 target | |
| C1 | 19% | Average Irish home; moderate comfort and bills | |
| C2 | 17% | Rural home with oil heating; slightly less efficient | |
| C3 | 14% | Typical apartment; rising heating costs likely | |
| D1 | 13% | Noticeably higher bills; good candidate for retrofit | |
| D2 | 11% | Expensive to heat; low comfort; upgrades recommended | |
| E | 9% | Poor energy performance; draughty | |
| F / G | 7% | Very high costs; full retrofit needed |
Relative efficiency (vs A1) is compared to an A1 home, it is not a physical measure of heat kept in a house, but a comparative metric to highlight energy savings across BER grades.
Calculated using CSO’s BER primary energy usage stats. (A1 delivered energy / grade delivered energy) × 100 (A1 = 100%) E.g: C1 → (1,100 / 6,050) × 100 = 18.2%
Despite the calculations used, a BER is only an indication of the energy performance of a home.
The BER calculation
A BER is based on the calculated energy performance and associated carbon dioxide emissions from room and water heating, ventilation and lighting under standardised conditions.
Although a BER takes into account how many people live at the property, it doesn’t include electricity used for purposes other than heating, lighting, pumps and fans.
Used in the calculation are:
- the house dimensions
- the house orientation
- types of window
- level of insulation
- heating & hot water system efficiencies
How to boost your BER
Improving your BER will reduce your energy costs and make your home warmer and more comfortable.
The majority of homes in Ireland are C or D, but the higher your rating the more energy savings you can make.
Here’s some ways to boost your BER and save money on your energy bills and enhance the value of your house.
How efficient is a C-rated home?
Most BER-rated homes in Ireland have a C-rating, and were built between 1980 and 2009.
- Gas is the main heating fuel used in a C-rated household (especially C1-rated homes)
- Home heating oil is more prevalent in C2 and C3-rated homes.
C-rated homes are more efficient than D-F rated homes at trapping heat, and may have some form of insulation.
As up to 30% of all heat is lost through the attic, and 35% escapes through walls and doors, the main things that will improve your homes’s BER rating include:
Before carrying out work, you should contact a registered BER Assessor who will visit your home and carry out an assessment.
Once your home is assessed, you will receive an advisory report which will suggest the improvements needed to bring your home to a B2 level.
Estimated heating costs by BER rating
Most Irish homes fall into the C-rated or D-rated range, which means their annual energy costs can be materially higher than those of a newer A-rated home.
The table below shows illustrative annual energy costs by BER grade, benchmarked against a typical Irish dual-fuel household bill.
It is designed to show how costs rise and fall with a home’s energy efficiency, rather than predict a household’s exact annual bill.
BER ratings are based on standardised building energy performance, while actual bills will vary depending on occupancy, heating habits, tariff and home size.
| BER grade | Estimated annual cost* (€) | Compared with C2 home | What it means in practice | |
|---|---|---|---|---|
| A1 | €430 | 0.13× | Very low running costs; highest efficiency. | |
| A2 | €645 | 0.20× | Excellent efficiency; very low energy demand. | |
| A3 | €1,076 | 0.33× | Strong performance; lower annual costs. | |
| B1 | €1,506 | 0.47× | Efficient newer home; manageable energy bills. | |
| B2 | €1,936 | 0.60× | Good efficiency; below the typical benchmark. | |
| B3 | €2,366 | 0.73× | Reasonable performance, but room to improve. | |
| C1 | €2,797 | 0.87× | Close to the midpoint of the market. | |
| C2 | €3,227 | Baseline | Benchmark used for a typical Irish dual-fuel home*. | |
| C3 | €3,657 | 1.13× | Typical older home; higher annual running costs. | |
| D1 | €4,174 | 1.29× | Older home with more noticeable heat loss. | |
| D2 | €4,819 | 1.49× | Common in older stock; clear upgrade potential. | |
| E1 | €5,507 | 1.71× | High energy demand; expensive to run. | |
| E2 | €6,196 | 1.92× | Very high running costs. | |
| F | €7,142 | 2.21× | Inefficient; retrofit strongly recommended. | |
| G | €8,175 | 2.53× | Extremely inefficient; very costly to heat. |
Based on an average annual Irish dual-fuel household bill, using standard unit rates correct as of April 2026.
Figures are illustrative and for comparison purposes only. Costs are modelled using BER band midpoints and benchmarked to a typical Irish annual dual-fuel bill.
They are designed to show the relative difference in energy costs between BER ratings, not predict a household’s exact annual bill. Actual costs vary by tariff, home size, heating system and usage.
Methodology
- We used the official BER rating bands published by the CSO, which measure a home’s energy performance in kWh/m²/year.
- To compare one BER rating with another, we used a midpoint for each band. For example, A2 = 37.5, C2 = 187.5 and D2 = 280. These midpoint values were used to show the relative gap in energy performance between homes.
- We then used a C2-rated home as the benchmark and anchored it to €3,227, based on our average annual Irish dual-fuel household bill benchmark using standard unit rates, correct as of April 2026.
- Each other BER rating was then scaled up or down from that C2 benchmark using this formula:
- Estimated annual cost = (BER midpoint ÷ 187.5) × €3,227
- This means homes with better BER ratings are shown with lower estimated annual costs, while less efficient homes are shown with higher estimated annual costs.
The figures are illustrative and intended to show how annual energy costs may rise or fall in line with BER performance. They are not a direct conversion of BER primary energy into an exact household bill.
Actual household energy costs will vary depending on tariff, home size, heating system, occupancy and usage patterns.
Sources:
What grants and financial help are available?
The SEAI offers a range of Home Energy Grants for homeowners and those undertaking a self-build. Home Energy Grants are available for the following:
- Wall insulation - up to €8,000
- Attic insulation - up to €2,000
- Windows and doors - up to €4,000
- Heating controls - up to €700
- Heat pump systems - up to €12,500
- Solar PV panels - up to €1,800
- Solar water heating - up to €1,200
What’s the SEAI one stop shop?
This SEAI’s one stop shop is a full-serviced home energy upgrade. It includes a home energy assessment, grant application, project management and any contractor work.
It’s a good option for homeowners who want multiple home energy upgrades and don’t want the hassle of managing a large project themselves.
Can you borrow money to carry out the work?
Yes, some other one stop shop packages, like An Post’s Green Hub or the credit union’s Greener Homes, include a loan as part of the offering.
As well as managing your grant application, BER assessment and contractor work, they’ll include a loan to cover any remaining costs.
Several Irish banks also offer Green personal loans and homeowner loans designed for improving your home’s energy efficiency. You’ll just need to provide evidence of work and grants obtained to benefit from discounted loan rates.
Compare discounted Green loans
Green mortgages
Some Irish banks are offering discounted mortgage rates for homeowners with a good BER rating. They’re called Green mortgages and are worth considering if your home has a rating of B3 or better.
Bank of Ireland even offers an innovative fixed mortgage based on a building’s BER Rating, with discounts applied on a sliding scale: so the higher your BER, the larger the discount.
Find out more about Green mortgages and whether you could qualify for this type of mortgage from some of Ireland’s leading banks like Bank of Ireland in our helpful guide.
BER FAQs
What do BER ratings like B2, C1, and D2 mean?
A Building Energy Rating (BER) measures how energy efficient your home is, from A1 (most efficient) to G (least efficient).
- B2-rated homes are highly efficient, often featuring modern insulation, condensing boilers or heat pumps, and renewable systems like solar PV.
- C1-rated homes are moderately efficient, typically with good insulation and modern gas or oil heating.
- D2-rated homes tend to have older boilers, minimal insulation, and higher energy bills.
A higher rating means a warmer, cheaper-to-run home that’s more attractive to buyers and may qualify for SEAI grants or green mortgage discounts.
How much does it cost to upgrade from D2 to C1 or better?
Costs depend on your home’s size and condition, but typical improvements, such as attic and wall insulation, boiler replacement, or new heating controls, range from €5,000 to €10,000 after SEAI grants.
Homes aiming for B2 or better may need additional measures like external wall insulation, triple glazing, or renewable systems.
Which upgrades give the best BER improvement for the money?
The most cost-effective upgrades include:
- Attic insulation quick, affordable, and immediately beneficial.
- Wall insulation (cavity or external).
- Upgrading to a condensing boiler or heat pump.
- Adding heating controls to better manage energy use.
- Solar PV also helps by reducing grid electricity demand, improving your overall energy performance.
Can you sell a home with a low BER rating?
Yes. All homes for sale or rent in Ireland must have a BER certificate, but there’s currently no minimum legal rating.
However, a low BER (like D2 or lower) can make a property less appealing to buyers due to higher running costs and lower comfort levels.
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