Building Energy Rating Guide: BER, EPC and Energy Scores
- What Is a Building Energy Rating?
- BER in Ireland and EPC in the UK: What’s the Difference?
- How Is a Building Energy Rating Calculated?
- How to Read a Building Energy Rating Certificate
- How to Improve Your Building Energy Rating
- Residential vs Commercial Building Energy Ratings
- What to Do After Improving Your Building Energy Rating
- Conclusion
- FAQs
A Building Energy Rating indicates the efficiency that a building is likely to achieve in its energy use as a result of design and equipment. The purpose of ratings is to educate owners, buyers, and tenants about a building's characteristics, including heating requirements, insulation, ventilation, and carbon emissions, and to offer a common way to compare the energy performance of different buildings.
In Ireland, BERs are used, and EPCs are used in the UK, but both are about building and not just one household's energy bills. The score can identify areas where efficiency improvements might be worth pursuing. Once unnecessary demand has been reduced, owners can take bigger steps, such as adding renewable generation and planning solar and battery storage to the building's new energy profile.
What Is a Building Energy Rating?
A building energy rating is a standardised assessment that indicates a property's energy performance. Formal rating systems rate attributes of the building and installed services based on specified assumptions, instead of just actual utility bills, which are highly dependent on how the building is used. This is because ratings are more helpful in comparing properties on a comparable basis.
What a Building Energy Rating Measures
A building energy rating assessment takes into account the characteristics that affect how much energy a property should use under normal circumstances. Depending on the assessment system, this can include insulation levels, walls, roofs, floors, windows, heating and hot-water systems, ventilation, lighting and renewable technologies. For instance Ireland's domestic BER approach uses standardised assumptions to calculate the energy needed for heating, water heating, ventilation and lighting and not the occupants' behaviour. The resulting score thus offers a more uniform estimate of the property's built-in energy efficiency than household bills alone.
How Energy Use and Emissions Affect the Rating
A building energy efficiency rating is based on the relationship between the expected energy demand and the environmental impact. The more delivered energy is needed to achieve the same level of comfort, the poorer the property's insulation or the heating system's efficiency; the better the insulation and the more efficient the heating system, the less energy is required to deliver the same level of comfort. Rating methodologies also take related carbon emissions into account. DEAP estimates delivered energy, primary energy, and CO₂ emissions annually based on standardised occupancy assumptions in Ireland. In the UK non-domestic EPCs, the performance of the building is presented through an index based on carbon-dioxide.
Why Building Energy Ratings Matter to Property Owners and Occupants
Building energy ratings give owners and occupants a better sense of the building's performance before actual use behaviour. The higher the rating, the lower the theoretical energy requirement and vice versa. Buyers and tenants can also use ratings to compare properties with similar attributes. UK homeowners who want more information about the domestic system can read how an EPC rating works. Importantly, the rating indicates energy performance and does not guarantee any specific household bill.
BER in Ireland and EPC in the UK: What’s the Difference?
BER and EPC both measure building energy performance but are part of different country energy assessment systems. A building energy rating Ireland search typically refers to the Irish BER system, whereas in the UK, a building energy rating is called an Energy Performance Certificate. This distinction matters because the same letter grade may not correspond to the same calculations or thresholds.
Building Energy Rating (BER) as Ireland’s Formal Energy-Performance System
The formal energy-performance system for residential and non-domestic buildings in Ireland is the Building Energy Rating (BER). For new BER certificates, the simplified numbering series A0, A, B, C, D, E, F and G has replaced the previous subcategories (e.g. A2 and B1). A0 is the best label and is reserved for the most energy efficient buildings without fossil fuels. BER is an asset rating, meaning it assesses the building and its systems based on standardised assumptions, not actual energy use by a specific tenant.
Energy Performance Certificates (EPCs) in the UK
The Energy Performance Certificate is the most common certificate for a building energy rating in the UK. EPCs consider factors like the building fabric and installed services and generally grade energy performance of a building on a scale of A to G, where A is best. EPCs are typically requested when qualifying properties are constructed, sold, or leased, with specific requirements varying across the UK nations. If a property owner requires a certificate, they can review the practical steps for obtaining an Energy Performance Certificate and then book an assessment with a suitable, accredited professional.
Why BER and EPC Scores Should Not Be Compared Directly
Although both BER and EPC certificates are based on letter bands, this does not imply that they are interchangeable. The building energy rating is generated based on the methodology, assumptions, energy factors and thresholds of the respective national system. The BER methodology and the UK EPC schemes thus should be understood in the context of each jurisdiction. It is not appropriate to assume that a B-rated Irish dwelling would have the same performance as a B EPC-rated UK dwelling. What matters is the certificate information, energy performance, and recommended interventions in the relevant country's system.
How Is a Building Energy Rating Calculated?
A formal building energy rating assessment takes into account the physical nature of the property, its equipment, and its systems, and does not reflect electricity or gas bills. Assessors input relevant building information into the approved methodology for the country in question to enable different properties to be compared under standardised conditions. Although the exact calculation varies between the BER methodology in Ireland and the EPC methodology in the UK, a few basic elements always play a role in the calculation.
Building Fabric, Insulation and Airtightness
The building envelope plays a significant role in the building energy efficiency rating as the walls, roofs, floors and openings control the ease of heat transfer between the interior and exterior environment. When calculating the heat loss, assessors take into account the type of construction, the level of insulation and other pertinent fabric properties. Airtightness can also influence the energy needed to achieve comfortable indoor conditions as uncontrolled air leakage adds to the heating requirement. A continuously insulated building with controlled air leakage will typically use less energy than a building of similar construction with poor-performing building fabric, provided appropriate ventilation is provided.
Heating, Ventilation and Hot Water Systems
Hot-water and heating systems can play a significant role in a building energy rating and account for a high percentage of total energy demand in many buildings. This includes the type of heating system, system efficiency, energy source, and controls. Ventilation can also affect calculated demand, especially in those buildings that are more airtight or mechanically ventilated. Even if the equipment is efficient, a strong rating cannot be achieved if it still loses a significant amount of heat through the building fabric. That is why, in most cases, the greatest benefits from heating improvements are achieved when they are part of an overall whole-building efficiency plan.
Windows, Lighting and Renewable Technologies
Elements such as glazing performance, lighting efficiency, and renewable technologies can all contribute to the final building energy rating calculation. Window type, frame performance, and glazing area affect heat loss and solar gain; efficient lighting can help lower calculated electricity demand. Renewable energy technologies that generate electricity on-site, such as solar PV can enhance the modelled energy performance of the building by providing a proportion of its electricity. Before assuming that all PV installations contribute the same amount to a rating, property owners should consider factors that influence solar panel output, such as PV capacity, PV orientation, and available sunlight.
Why an Online Energy Rating Calculator Is Only an Estimate
An online building energy rating calculator can help indicate some of the impacts a set of upgrades may have on a property, but it cannot replace an accredited assessment. Online tools may use simplified information, such as a floor's area, the type of heating, and details about insulation and windows; an official rating may require much more detailed building information and an approved rating tool. Owners can use estimates to consider improvement options before investing, but they should not be considered a substitute for a formal BER/EPC certificate. Final ratings are based on methodology and verified property information.
How to Read a Building Energy Rating Certificate
A building energy rating certificate is only valuable if you use it correctly. The headline grade gives a quick indication of how well you are performing, but the certificate can also provide calculated energy demand, emissions, and areas with potential for improvement. Consider them side by side to provide property owners with a stronger foundation to choose the best improvements to prioritize.
Understanding Energy-Performance Grades and Scores
Most often, a building energy rating chart is represented by a letter grade or a performance band. The higher the rating, the more energy-efficient the property is, and the lower the rating, the more energy the property uses under standard assessment conditions. The letter, however, cannot be used to determine why a building received that result. Owners should also consider the underlying score, building attributes and the systems installed. If a property is located on the edge of two grades, the improvements needed for it to float up may be relatively minor, but for another property on the same grade, the improvements might be more extensive.
Estimated Energy Consumption and Carbon Emissions
A building energy rating certificate can contain estimated values of energy use and carbon emissions. These values assume the approved assessment methodology and are not necessarily the same as those of current occupants, and actual bills may vary. In a home with fewer rooms, or rooms set to lower temperatures, the home may consume less energy than indicated in the certificate, and a home that consumes more energy may generate higher bills. The figures are most helpful in comparing the building's theoretical performance and determining which systems have the greatest impact on the building's overall demand and emissions.
Recommended Improvements and Potential Savings
Many certificates also list potential improvements that could raise the building energy efficiency rating of the property, such as insulation, heating controls, glazing changes and renewable energy technology. Recommendations are a starting point, not a required sequence of renovations. There are a number of reasons why one measure may be the first to be considered, including costs, condition of building, technical feasibility, and future plans for work. If multiple improvements are planned, reducing heat loss and unnecessary demand before replacing major energy systems can help prevent oversizing equipment and provide a better understanding of the property's future energy needs.
How to Improve Your Building Energy Rating
When implementing a building energy rating improvement, measures can be taken to either reduce the property's underlying energy demand or introduce new technologies. The best order is to first reduce heat loss, then add heat and controls, and finally renewables and expanded energy systems. This helps ensure investments are scaled around an efficient building rather than making up for losses that could have been avoided.
Reduce Heat Loss With Insulation and Airtightness Upgrades
Improvements to insulation and airtightness can enhance a building energy efficiency rating by decreasing the amount of heat needed to keep buildings warm in cold weather. This can include loft, roof, wall, or floor insulation and draught-proofing around appropriate windows, doors, and service penetrations, depending on the property. However, adequate ventilation should still be provided to prevent moisture and indoor air quality issues. Owners who are looking to make larger renovations can also consider any available energy-efficiency grants, if applicable. When improving or upgrading a heating system, it is often better to start with the fabric first to reduce its weaknesses, then make the heating more efficient to avoid oversizing the system.
Improve Heating Efficiency and Smart Controls
The performance of the heating-system can have significant impact on the energy rating of buildings, especially if the building is fitted with ageing equipment or limited controls, producing unnecessary energy demand. Improvements can involve upgrading of inefficient heating equipment, installing appropriate thermostatic or zoning controls and commissioning of systems. Smart controls can help align heating time with occupancy rather than running constant heating. But if you replace the heating system without first minimising large heat-loss areas, you may end up sizing equipment to sustain old heat-loss requirements. Heating improvements, combined with fabric improvements, will tend to offer a more consistent path to achieving overall energy performance.
Add Solar PV and Other Renewable Technologies
Renewable technologies can contribute to a higher building energy rating by providing a portion of the building's energy demand through conventional energy. Solar PV can produce electricity onsite, and other technologies like heat pumps can lessen fossil-fuel heating requirements, if the building and system design are appropriate. The effect on the final rating varies with the assessment methodology, the size of the system, and other building characteristics. Renewables should therefore not be regarded as a sure-fire path to a specific certificate rating but as an integral part of the overall energy concept.
Reduce Energy Demand Before Adding New Energy Systems
Demand reduction should be prioritised in a practical building energy rating guide before installing major new energy infrastructure. The amount and timing of the energy required to the property can be modified with better insulation, efficient heating, appropriate controls and reduced electrical loads. These measures provide a clearer foundation for owners to choose the level of solar generation/battery capacity or other technology. This sequence can help eliminate oversized equipment and help design new systems for better buildings.
Residential vs Commercial Building Energy Ratings
The assessment applies to homes and business premises, but as buildings get bigger and services more complex, the assessment is more detailed. A building energy rating typically covers common household systems, while a commercial rating may require consideration of multiple zones, large HVAC systems, lighting controls, and varying usage patterns.
Domestic Ratings for Homes
Domestic assessment evaluates the features that affect the likely energy efficiency of dwellings such as insulation, glazing, heating systems, hot water systems, ventilation and renewable technologies. This building energy rating is calculated using standardised assumptions and does not reflect the real-life occupation patterns of the current building tenants, but enables a more consistent, comparable rating of homes. The BER framework is used in Ireland, and typically, homes in the UK and the British Isles have domestic EPCs. Actual household bills may still vary significantly depending on thermostat settings, how many people are in the house, what appliances are used, and energy prices; use the certificate as an indicator of how the home is performing, not as a bill predictor.
Commercial Ratings for Offices and Business Premises
Commercial building energy ratings may require considering a more extensive list of energy-consuming systems than do residential building energy ratings. Offices, shops, and other business premises can include mechanical ventilation, air conditioning, high lighting levels, lifts, commercial hot water systems, and special equipment. They can also be open for different hours and have varying day of the week schedules from one location to the next within the same property. Commercial ratings thus evaluate the building and its permanent facilities in accordance with the jurisdiction's methodology. The certificate does not show a standardised picture of energy performance – actual business consumption will also be dependent on operational schedules and equipment used by the occupants.
Why Larger Buildings Require More Complex Assessments
Larger properties may have multiple thermal zones, each having different uses, temperatures, and occupancy, with varying ventilation needs. This makes performing a building energy rating assessment more complicated than rating a relatively uniform house. Considerations may include glazing orientation, HVAC distribution, lighting systems, controls, and the interaction between spaces. Additional complexities arise when offices and retail space or communal facilities exist on the same property, but under different circumstances, as in mixed-use buildings. More detailed modelling can help ensure the rating is based on the building's fixed characteristics and services, rather than overly simplistic assumptions that may not reflect the operation of a large building.
What to Do After Improving Your Building Energy Rating
While improving the building energy rating is important, it is also a milestone that should influence planning for the building's future energy system. Demand can be significantly reduced with better insulation, heating efficiency and controls and so earlier estimates of electricity demand may not apply to the energy use in the upgraded building. If consumption is reassessed up front, it can provide a stronger basis for determining the suitability of solar generation and battery storage.
Reassess Electricity Demand After Efficiency Upgrades
Owners should take the opportunity to evaluate post-efficiency electrical consumption and when it occurs. Heating improvements, better control systems, and reduced heat loss can alter overall consumption and peak demand. Monitoring for several weeks or months after the upgrade can therefore provide a more realistic baseline for future planning for energy use and conservation. Further efforts to save energy at home can also help separate energy demand from energy-avoidable consumption. This keeps the property from being ‘oversized’ for the new solar or storage system, since the system was built to the property's old energy profile.
Use Solar Generation More Effectively With Energy Storage
Solar PV production and consumption do not necessarily happen simultaneously, although PV can decrease grid electricity demand when it is producing. During the day, when the sun is out, a property could generate more electricity than it uses, and import it again later in the day, when it's darker. Some of that excess can be stored in batteries for later use, boosting solar self-consumption. However, storage itself would not necessarily lead to an improvement in a building energy efficiency rating, since formal assessments are based upon the energy efficiency rating methodology. It would support more efficient renewable electricity management after the building's overall energy demand has been lowered.
EcoFlow STREAM 5000 for New Solar and Storage Setups
EcoFlow STREAM 5000 offers a practical initial solution for properties that have taken steps toward reducing energy consumption and are now considering integrating solar power generation with storage. Its storage and solar-input capacities can be designed around the building's new electricity demand, rather than its previous electricity use. This is especially important when the next step after improving the building's energy rating is designing a coordinated renewable-energy system that can expand in the future.
EcoFlow STREAM AC 5000 for Existing Solar Systems
If a PV system is already in place, EcoFlow STREAM AC 5000 is more suitable for retrofitting solar energy systems to include storage. It enables excess solar power to be stored for future use, which can be especially beneficial after solar efficiency has improved and consumption has decreased. This simplifies future planning of the storage system by accounting for changes in the property's electricity use after building energy rating assessment and improvements.
Conclusion
A building energy rating is a realistic way to understand how efficiently a property is designed to use energy, and where improvements can make the most difference. The best outcomes are typically achieved by optimising insulation, airtightness, heating, controls, and renewable generation in a sensible order, whether in Ireland's BER or a UK EPC.
Once these improvements lower the building's overall demand, energy storage can support the building's broader electricity strategy. EcoFlow STREAM 5000 is ideal for properties considering combining solar and storage, and EcoFlow STREAM AC 5000 is better suited to existing solar systems that need more storage for later use.
FAQs
How long is a building energy rating certificate valid in Ireland?
The building energy rating certificate Ireland is typically valid for 10 years as long as there are no significant changes which impact the energy performance of the building. If major changes, such as the replacement of the heating system, or significant extensions or other efficiency improvements are to be made, a new assessment may be required before the certificate's expiration date. Therefore, property owners should review the building to determine whether recent works have materially altered it, rather than relying on the original expiry date.
Can a poor building energy rating affect a property’s sale or rental?
Yes, a low building energy rating can affect the perception of potential purchasers or tenants about expected energy use and necessary future upgrades.
Lower ratings may indicate greater heating demand.
Buyers may factor retrofit costs into their decisions.
Better-rated properties can appear more attractive to energy-conscious occupants.
Occupants living in better-rated properties may find their building more appealing when considering energy.
Does battery storage automatically improve a building energy rating?
No, adding battery storage does not automatically increase a building energy efficiency rating. Formal BER/EPC methodologies evaluate certain building parameters and systems installed and the treatment of battery storage will vary as per the calculation methodology. The most obvious use of a battery is usually energy management – to store some excess solar power for later use to boost solar self-consumption. When the primary goal is to improve the building's assessed energy performance, the focus should therefore remain on fabric changes, efficient heating, and suitable controls.
Should you add battery storage before or after an energy-rating assessment?
Usually, the first step is to complete a building energy rating assessment and have a plan of efficiency changes to better understand the building's energy usage and size the battery accordingly. Electricity demand can be reduced and the timing of electricity use can be altered through improvements to insulation, heating controls and/or heating equipment. With this understanding of an improved consumption profile, storage can be sized around realistic needs. While it may be sensible to take battery systems into account when planning a building renovation, the battery capacity should ideally be based on the building's expected post renovation energy demand.
Who can take building energy rating courses and become a BER assessor?
To become a BER assessor in Ireland, it is not enough to just attend building energy rating courses. Applicants must have the relevant qualification and competency, complete approved assessor training, and comply with the registration requirements for the BER scheme. Several factors govern the requirements for assessing domestic versus non-domestic buildings. Before entering training, prospective assessors should therefore ensure that they review the current SEAI entry and/or registration criteria, as these criteria may evolve over time.