The short answer
- You need a BER when a commercial building is built, sold or rented. Sale and letting adverts must show it, and a certificate is valid for 10 years unless a material change affects energy performance.
- Non-domestic BERs are calculated with SEAI's NEAP method, normally in SBEMie software, by an SEAI-registered assessor. The heat lost through the roof, walls, floor and air leakage feeds straight into the result.
- Roof insulation usually does most for the rating on single-storey commercial and industrial buildings, because the roof is the largest and often the worst-performing element. Spray foam also cuts air leakage.
- Cool-roof coatings such as GacoFlex S42 (initial solar reflectance 0.87) reduce solar heat gain. In Ireland that mainly helps buildings that overheat or are mechanically cooled. Ask your assessor how the software treats it before you rely on it for the rating.
What a commercial BER is
A Building Energy Rating (BER) is the energy label for a building. For homes it is calculated with SEAI's domestic method. For offices, warehouses, shops, factories, hotels and other non-domestic buildings it uses the Non-domestic Energy Assessment Procedure (NEAP). SEAI's default software for NEAP is SBEMie. The calculation estimates the energy the building would use, under standard conditions, to heat, cool, ventilate, light and provide hot water for its type of use. It then compares that with a reference building.
The result is a BER certificate and an advisory report. The certificate carries the rating. The advisory report lists improvements that would reduce energy use. A BER assessor registered with SEAI produces both and publishes them to SEAI's national register.
A BER is not a measurement of your actual energy bills. Two identical warehouses with the same BER can have very different bills if one is heated all day and the other is barely heated. That distinction matters when you decide what to upgrade, and it is covered below.
When you need a BER for a commercial building
According to SEAI, a valid BER certificate and advisory report are required when a building is:
- constructed, before it is first occupied
- offered for sale
- offered for rent
Commercial buildings are included. Advertisements for a sale or letting must show the BER, and SEAI publishes advertising guidelines for agents and owners. A BER certificate is valid for 10 years, unless a material change in the building could affect its energy performance. A significant insulation upgrade is exactly that kind of change, so a new assessment after the works lets you show the improvement.
Display Energy Certificates for public buildings
A Display Energy Certificate (DEC) is a separate thing. It is based on the actual metered energy use over a year, not a standard calculation, and it is updated every year. SEAI states that DECs are required for buildings of public bodies with a total useful floor area over 250 m² that are frequently visited by the public, and for other buildings over 500 m² that are frequently visited by the public. They are displayed prominently. Because a DEC reflects real consumption, a fabric upgrade that cuts heating use shows up in the next year's DEC.
Is there a minimum BER for letting a commercial building?
There is currently no minimum BER that a commercial building must reach before it can be let in the Republic of Ireland. The rating must be produced and advertised, but no rule stops a low-rated unit from being let. Tenants, lenders and buyers increasingly read the rating, though, and a poor one can weaken a negotiation. EU law is moving in that direction for non-residential buildings: see the EPBD recast section below.
EPBD recast and minimum energy performance standards (updated 15 September 2026)
The EU has recast its Energy Performance of Buildings Directive. The new text is Directive (EU) 2024/1275 of 24 April 2024, published in the Official Journal of the European Union on 8 May 2024. The Irish Government's press release of 8 May 2026 states that, as part of transposition, a number of actions were required before 29 May 2026. This section sets out what the directive says for owners of commercial and industrial buildings.
Minimum energy performance standards for non-residential buildings
Article 9(1) requires Member States to set minimum energy performance standards (MEPS) for non-residential buildings. Each Member State sets two thresholds, expressed as primary or final energy use in kWh/(m²·y):
- a "16 % threshold", set so that 16% of its national non-residential building stock is above it
- a "26 % threshold", set so that 26% of its national non-residential building stock is above it
The standards must ensure, at least, that all non-residential buildings are below the 16% threshold from 2030 and below the 26% threshold from 2033. In plain terms, the worst-performing non-residential buildings will have to be improved first. The directive leaves the numeric thresholds to each Member State, so confirm the Irish figures with SEAI or the Department before you plan around them.
Zero-emission new buildings
Article 7(1) requires new buildings to be zero-emission buildings from 1 January 2028 for new buildings owned by public bodies, and from 1 January 2030 for all new buildings.
Solar energy on buildings
Article 10(3) requires the deployment of suitable solar energy installations, if technically suitable and economically and functionally feasible. The dates most relevant to commercial owners are:
| By | Buildings covered |
|---|---|
| 31 December 2026 | All new public and non-residential buildings with useful floor area larger than 250 m² |
| 31 December 2027 | Existing public buildings larger than 2,000 m² |
| 31 December 2027 | Existing non-residential buildings larger than 500 m², where the building undergoes a major renovation or an action that requires an administrative permit for building renovations, works on the roof or the installation of a technical building system |
| 31 December 2028 | Existing public buildings larger than 750 m² |
| 31 December 2029 | All new residential buildings, and all new roofed car parks physically adjacent to buildings |
| 31 December 2030 | Existing public buildings larger than 250 m² |
Source: Directive (EU) 2024/1275, Article 10(3).
Article 10(4) also says Member States shall take into account structural integrity, green roofs, and attic and roof insulation, where appropriate. For a building owner, that is a good reason to look at the roof's condition and insulation before panels go on top of it.
The A to G scale and the A0 class
Under the directive's energy performance certificate provisions, the scale runs from A to G. A corresponds to zero-emission buildings and G to the very worst-performing buildings in the national stock when the scale is introduced. Member States that already designated zero-emission buildings as "A0" on 29 May 2026 may keep that designation instead of class A.
What Ireland has announced
According to the Department of Housing, Local Government and Heritage press release of 8 May 2026:
- a simplified BER scale for non-residential buildings is introduced from 24 May 2026, going from A to G with a new A0 category for zero-emission buildings that do not use fossil fuels
- subcategories are removed, reducing the levels shown on the certificate from 15 to 8
- the scale applies to public buildings, hotels, retail and office space, amongst others
- the transposition actions named are rescaling BER classes and defining zero-emission buildings, providing ZEB renovate thresholds for renovated non-residential buildings, and updating the calculation methodology for BER classes
- existing BER certificates remain valid for sale, rent or advertisement, for up to ten years from their date of issue
What to do now: if your building sits near the bottom of the scale, the roof is usually the first place to look. Ask your BER assessor to model a roof and wall upgrade, and keep the evidence of what was installed. This section summarises the directive and the Government announcement. It is not legal advice, and the statute and SEAI's guidance have the final say.
Selling, letting or upgrading?
Send your current BER advisory report if you have one. We will arrange a free survey of the roof and walls and give you a fixed price.
How the building fabric affects the rating
NEAP models the building zone by zone. For each zone it takes the construction of every element and its U-value, the glazing, the air permeability, the heating and cooling systems, the lighting and the activity. The fabric affects the result in three main ways.
1. U-values of the roof, walls and floor
Every square metre of envelope loses heat in proportion to its U-value. On a single-storey industrial or retail unit, the roof is usually the largest element, and often the worst. Uninsulated single-skin metal or fibre cement sheets perform very poorly. Bringing a roof like that up to the TGD L 2022 Table 10 figure for insulation on the slope, 0.25 W/m²K, is often the biggest single fabric improvement available.
2. Air permeability
The assessor enters an air permeability figure. A measured value from a pressure test is better than a default for an older building. Air leaking through laps, eaves and ridges carries heat out with it. Closed-cell spray foam applied to the underside of the roof seals those paths as it insulates. A test after the works gives the assessor a real, usually better, number to use. For comparison, TGD L 2022 treats 5 m³/(h·m²) at 50 Pa as the reasonable upper limit for new buildings other than dwellings.
3. Thermal bridging
Junctions such as eaves, ridges, purlins and wall-to-roof connections leak heat. Continuous insulation that wraps those junctions reduces the losses. A board system broken at every purlin does not.
| Upgrade | What it changes in the calculation | Typical fit |
|---|---|---|
| Closed-cell spray foam to underside of roof | Roof U-value, air permeability, junction losses | Single-skin metal or fibre cement roofs, warehouses, workshops |
| Spray foam to wall cladding | Wall U-value, air leakage at laps and base | Uninsulated cladding on sheds and units |
| Airtightness sealing and test | Measured air permeability replaces default | Any building with visible gaps at eaves, doors, laps |
| Reflective silicone roof coating | Solar gain through the roof (see below) | Buildings that overheat or are cooled |
| Heating, lighting, controls | Services efficiency | Almost every building (outside our scope) |
Fabric changes interact with services. A building with very efficient heating will see a smaller change from insulation than one with old direct-fired heaters.
Cool-roof coatings in Ireland: what they really do
A cool roof reflects sunlight instead of absorbing it. GacoFlex S42 is a 100% silicone liquid roof coating in white. It has a published initial solar reflectance of 0.87 and a Solar Reflectance Index of 110. Reflectance falls as a roof weathers, and the published three-year figures are 0.69 and SRI 84. Always compare products on their weathered figures, not just their day-one numbers.
In a hot climate, a roof that reflects most of the sun cuts air-conditioning costs substantially. Ireland is different, and it is better to say so plainly:
- Where a reflective roof helps in Ireland: buildings that are mechanically cooled, such as data rooms, cold stores, food production, chilled distribution and some retail. It also helps buildings with poorly insulated roofs that overheat in summer, such as workshops and offices under metal roofs, and roofs where a lower surface temperature is useful for comfort or process reasons.
- Where it does little: a heated but uncooled building in winter. A reflective roof keeps out solar heat you might otherwise have welcomed. For heated buildings, insulation does far more for energy use than reflectance.
How much credit a reflective roof earns in a BER depends on how the calculation software handles roof solar properties and on the building's cooling. Ask your BER assessor how they would model it before you commission a coating for rating purposes. The main reason to coat a commercial roof is still to waterproof it and extend its life. S42 carries a 20-year manufacturer-backed product warranty when applied at 0.90 mm wet film in a single pass. Any energy benefit is a bonus, and it should be judged on your building's cooling load, not assumed.
Best of both: on a roof that leaks and is uninsulated, the order is usually waterproof first, then insulate the underside. Our flat roof leaks guide explains when a coating is the right repair and when it is not.
Planning an upgrade that moves the rating
- Start with the existing BER and advisory report. If the building has one, it shows the assumptions the assessor used, including the roof and wall constructions and the air permeability. If those assumptions are defaults, a survey and a pressure test may already show the building is better or worse than modelled.
- Ask the assessor to model options. Many assessors will run "what if" scenarios: roof to 0.25 W/m²K, walls to 0.35 W/m²K, a measured air permeability. That tells you which upgrade gives the most improvement for the money before you spend it.
- Get the target U-values in writing. They drive the thickness, and the thickness drives the price.
- Book a free survey. An approved installer inspects the roof and walls, measures the areas including profile allowances, and confirms substrate condition and access.
- Keep the evidence. After installation, keep the specification, installation record, product data sheets and Declarations of Performance. Your assessor needs evidence of what was installed, not a description.
- Reassess. A new BER after a material change records the improvement for the next sale or letting.
If the building's roof is asbestos cement, the upgrade route has extra steps under the Exposure to Asbestos Regulations. Our asbestos cement roofs guide sets them out.
For landlords, tenants and buyers
Landlords use a better rating to market a unit, and upgrades at re-letting avoid disrupting a tenant. A roof upgrade between tenancies is also the easiest time to handle access and any asbestos issues.
Tenants on a full repairing lease pay the heating bills. A leaking, uninsulated roof costs them every winter. The BER advisory report is a useful starting point for a conversation with the landlord about who upgrades what.
Buyers and lenders read the BER as a signal of future cost. A low-rated warehouse with a failing roof is priced accordingly. A survey report and a fixed price for the upgrade help turn that into a number you can negotiate with.
Whichever you are, the practical first step is the same: find out what the building is actually made of and what it would take to improve it. That is what the free survey is for. We cover commercial buildings across the Republic, from County Dublin business parks to units in County Limerick and County Galway.