The guidance in this section relates to the re-use of data from a previous BER assessment of a dwelling that was carried out by another Assessor.
The key aim in introducing this change is to avoid situations where a new BER of a dwelling is worse than a previous BER because the evidence to support the use of non-default values is no longer available.
Henceforth, Assessors will be able to re-use non-default data from a previous assessment of a dwelling, even where the supporting evidence for that non-default data is no longer available.
The following points regarding the re-use of data must be borne in mind:
| Data Entry Item | Guidance on re-use of data | Notes and examples |
|---|---|---|
| Type of Rating | As the re-use of data only applies to Existing Dwelling BERs, this must be updated to ‘Existing Dwelling’. | A ‘New Dwelling - Final’ BER must be updated to ‘Existing Dwelling’. |
| Purpose of rating | The purpose of the rating must be updated in accordance with the purpose of the new BER. | |
| Building Regulations | As the re-use of data only applies to Existing Dwelling BERs, this information must not be changed, unless onsite evidence shows otherwise. | |
| Date of Plans | As the re-use of data only applies to Existing Dwelling BERs, this information does not need to be changed. | |
| Planning Reference | As the re-use of data only applies to Existing Dwelling BERs, this information does not need to be changed. | |
| Assessor Comments | This is an editable field and can be overwritten as necessary as it does not affect the BER. | |
| Survey Description | This is an editable field and can be overwritten as necessary as it does not affect the BER. |
| Data Entry Item | Guidance on re-use of data | Notes and examples |
|---|---|---|
| Dwelling type | Dwelling type must be confirmed and any error corrected. | |
| Year | The Year of Construction entered in a previous BER may be re-used in the absence of supporting evidence from the previous BER, though any errors or conflicting evidence found during the onsite survey must be considered and changes made, if necessary. | |
| Extended | Where a part of the dwelling has been identified as an extension in the previous BER, it may continue to be assumed as such in the absence of supporting evidence from the previous BER, though any errors or conflicting evidence found during the onsite survey must be taken into account and changes made, if necessary. | |
| MPRN | The MPRN of the dwelling must be confirmed as being correct for the dwelling address. If the MPRN is incorrect the new BER must be published with the correct MPRN. | |
| BER Number | The BER Number of the dwelling must be retained, though any errors found during the onsite survey must be corrected. | |
| Property address | The property address must be confirmed and any errors corrected. | |
| Eircode | The Eircode must be confirmed and any error corrected. |
| Data Entry Item | Guidance on re-use of data | Notes and examples |
|---|---|---|
| Number of Storeys and Storey heights | The Assessor must carry out full onsite measurements to verify the existing entries and make corrections where necessary. | The supporting evidence required for survey dimensions is the same as for an assessment where data is not re-used. |
| Living area | The Assessor must assess the Living area and correct the entry if necessary. | The supporting evidence required for the Living Area is the same as for an assessment where data is not re-used. |
| Floor Location | The entry for Floor Location must be confirmed and any errors corrected. | |
| Floor Type | The entry for Floor Type must be confirmed and any errors corrected. | |
| Age Band |
Where there is no evidence onsite to contradict an Age Band entry from a previous BER, that Age Band can be re-used, even where evidence supporting the Age Band is not available. However, where there is evidence onsite that contradicts an Age Band entry from a previous BER, that Age Band must not be re-used. It should be updated in accordance with the onsite evidence. |
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| Description | This is an editable field and can be overwritten as necessary as it does not affect the BER. | |
| Floor area | The Assessor must carry out full onsite measurements to verify the existing floor area entries and make corrections where necessary. | The supporting evidence required for floor area is the same as for an assessment where data is not re-used. |
| Exposed Perimeter | The Assessor must carry out full onsite measurements to verify the existing exposed perimeter entry and make corrections where necessary. | The supporting evidence required for Exposed Perimeter is the same as for an assessment where data is not re-used. |
| Wall area (exposed to ground) |
This entry is only required for “heated basement – walls exposed to ground”. The Assessor must carry out full onsite measurements to verify the existing wall area entry and make corrections where necessary. |
The supporting evidence required for Wall area (exposed to ground) is the same as for an assessment where data is not re-used. |
| Floor U-value |
A default floor U-value depends on,
The conditions for data re-use for each of these entries are outlined above. If any of these need to be updated in the new BER, then the U-value should be updated accordingly. Non-default floor U-values from the previous BER can be re-used, even where evidence supporting the U-value is not available. However, where there is evidence onsite that contradicts a non-default floor U-value entry from a previous BER, that U-value must not be re-used. It should be updated in accordance with the onsite evidence. |
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| Underfloor heating | The presence of underfloor heating must be confirmed during the onsite survey and any error found must be corrected. | |
| Room in roof | The selection of room in roof must be verified during the onsite survey and any error found must be corrected. | |
| Include in compliance check | Not relevant to re-use of data. |
| Data Entry Item | Guidance on re-use of data | Notes and examples |
|---|---|---|
| Roof Type | The entry for Roof Type must be confirmed and any errors corrected. | |
| Description | This is an editable field and can be overwritten as necessary as it does not affect the BER. | |
| Include in compliance check | Not relevant to re-use of data. | |
| Insulation Unknown | This entry must be confirmed onsite and any error corrected. | If the previous BER had a roof section with Insulation unknown, but the insulation is now accessible, then the original entry must be discarded, and measurement of the insulation must be carried out following standard guidance. |
| Insulation Thickness | This entry must be confirmed onsite and any error corrected. | |
| Roof Age Band |
Where there is no evidence onsite to contradict a roof Age Band entry from a previous BER, that Age Band can be re-used, even where evidence supporting the Age Band is not available. However, where there is evidence onsite that contradicts a roof Age Band entry from a previous BER, that Age Band must not be re-used. It should be updated in accordance with the onsite evidence. |
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| Roof area | The Assessor must carry out full onsite measurements to verify the existing roof area entries. | |
| Roof U-value |
Where a roof U-value relates to a space that cannot be properly investigated in a survey, i.e. where the insulation is inaccessible, the U-value from the previous BER can be re-used. Similarly, non-default roof U-values from the previous BER can be re-used, even where evidence supporting the U-value is not available. However, where there is evidence onsite that contradicts a non-default roof U-value entry from a previous BER, that U-value must not be re-used. It should be updated in accordance with the onsite evidence. Where possible, default U-values must be checked, e.g. confirming insulation thickness, and any errors found during the onsite survey must be corrected. |
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| Ventilated or unventilated attic space | Where a roof space of a dwelling has been identified as an unventilated space in the previous BER, it may continue to be assumed as such in the absence of supporting evidence from the previous BER, though any errors found during the onsite survey must be corrected. |
| Data Entry Item | Guidance on re-use of data | Notes and examples |
|---|---|---|
| Wall Type | The entry for Wall Type must be confirmed and any error corrected. | |
| Wall Age Band |
Where there is no evidence onsite to contradict a wall Age Band entry from a previous BER, that Age Band can be re-used, even where evidence supporting the Age Band is not available. However, where there is evidence onsite that contradicts a wall Age Band entry from a previous BER, that Age Band must not be re-used. It should be updated in accordance with the onsite evidence. |
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| Wall area | The Assessor must carry out full onsite measurements to verify the existing wall area entries. | |
| Wall U-value |
A default wall U-value depends on,
The conditions for data re-use for each of these entries are outlined above. If either of these need to be updated in the new BER, then the U-value should be updated accordingly. Non-default wall U-values from the previous BER can be re-used, even where evidence supporting the U-value is not available. However, where there is evidence onsite that contradicts a non-default wall U-value entry from a previous BER, that U-value must not be re-used. It should be updated in accordance with the onsite evidence. |
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| Description | This is an editable field and can be overwritten as necessary as it does not affect the BER. | |
| Include in compliance check | Not relevant to re-use of data. | |
| Wall is semi-exposed | This entry must be confirmed and any error corrected. |
| Data Entry Item | Guidance on re-use of data | Notes and examples |
|---|---|---|
| Number of Items | This entry must be confirmed and any error corrected. | |
| Description | This is an editable field and can be overwritten as necessary as it does not affect the BER. | |
| Door area | The Assessor must carry out full onsite measurements to verify the existing door area entries. | |
| Door U-value |
Default U-values must be checked and any errors found during the onsite survey must be corrected. Non-default door U-values from the previous BER can be re-used, even where evidence supporting the U-value is not available. However, where there is evidence onsite that contradicts a non-default door U-value entry from a previous BER, that U-value must not be re-used. It should be updated in accordance with the onsite evidence. |
| Data Entry Item | Guidance on re-use of data | Notes and examples |
|---|---|---|
| Number of Items | This entry must be confirmed and any error corrected. | |
| Description | This is an editable field and can be overwritten as necessary as it does not affect the BER. | |
| Window Area | The Assessor must carry out full onsite measurements to verify the existing area entries. | |
| Window orientation | Window orientation data must be reviewed onsite, and any errors found during the onsite survey must be corrected. | |
| Window U-value and solar transmittance |
Non-default window U-values and g-values from the previous BER can be re-used, even where evidence supporting the U-value is not available. However, where there is evidence onsite that contradicts a non-default window U-value entry from a previous BER, that U-value must not be re-used. It should be updated in accordance with the onsite evidence. For default window U-values, the glazing type (single, double, triple) must be checked for each window:
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Where it is possible to identify the window model onsite, it should be checked against the model referenced in the assessment. If the models do not match, the data must not be re-used. |
| Window over shading | Overshading data must be reviewed onsite, and any errors found during the onsite survey must be corrected. | |
| Blinds/Curtain Type, Overhang, Overhang Depth | These do not affect the BER and are outside the scope of this document. | |
| Roof Window | This entry must be reviewed onsite, and any errors found during the onsite survey must be corrected. |
| Data Entry Item | Guidance on re-use of data | Notes and examples |
|---|---|---|
| Thermal bridging factor |
A non-default thermal bridging factor may be re-used, even where evidence supporting the y-value is not available. However, if any changes to the building fabric have occurred that would affect the thermal bridging factor, then the previous factor cannot be used. |
Examples of changes that would change the thermal bridging factor:
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| Thermal mass category |
The thermal mass category must be reviewed onsite, and any errors found during the onsite survey must be corrected. Where the previous BER was a ‘New Final BER’, which means it was calculated using the AmAf approach, the thermal mass category may be re-used. |
| Data Entry Item | Guidance on re-use of data | Notes and examples |
|---|---|---|
| Count of chimneys | The chimney count must be reviewed onsite, and any errors found during the onsite survey must be corrected. | |
| Count of open flues | The open flue count must be reviewed onsite, and any errors found during the onsite survey must be corrected. | |
| Intermittent fans and background / passive vents | The count of intermittent fans and vents must be reviewed onsite, and any errors found during the onsite survey must be corrected. | |
| Flueless combustion room heaters | The count of flueless combustion heaters must be reviewed onsite, and any errors found during the onsite survey must be corrected. | |
| Is there a draught lobby on main entrance? | The presence of a draught lobby must be confirmed in the onsite survey, and any error must be corrected. |
| Data Entry Item | Guidance on re-use of data | Notes and examples |
|---|---|---|
| Air permeability test result | Data from an air pressure test may be re-used even where the supporting evidence is unavailable. If changes have been made to the dwelling that render the pressure test invalid, then the data must not be re-used. |
Examples of changes that would affect the air permeability:
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| Structure type | The structure type must be confirmed in the onsite survey, and any error must be corrected. | |
| Is there a suspended wooden ground floor? | The ground floor type must be confirmed in the onsite survey, and any error must be corrected. | |
| Sheltered sides | The count of sheltered sides must be confirmed in the onsite survey, and any error must be corrected. | |
| Number of Openings / Number of Draught Stripped Openings | The count of Openings and Draught Stripped Openings must be confirmed in the onsite survey, and any errors must be corrected. |
| Data Entry Item | Guidance on re-use of data | Notes and examples |
|---|---|---|
| Whole house mechanical ventilation | The presence of mechanical ventilation must be confirmed in the onsite survey, and any errors must be corrected. Non-default data for a mechanical ventilation system may be re-used, even where evidence supporting this data is not available. Where it is possible to identify the MV model onsite, it should be checked against the MV model referenced in the assessment. If the models do not match, the data should not be re-used. |
| Data Entry Item | Guidance on re-use of data | Notes and examples |
|---|---|---|
| Heating systems properties, emitter type and controls |
Information on heating system properties,
must be confirmed in the onsite survey, and any errors must be corrected. |
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| Boiler interlock present | The presence of boiler interlock must be confirmed in the onsite survey, and any error must be corrected. | |
| Delayed start thermostat present | The presence of a Delayed start thermostat must be confirmed in the onsite survey, and any error must be corrected. | |
| Integrated thermal store present | The presence of an Integrated thermal store present must be confirmed in the onsite survey, and any error must be corrected. | |
| Is the heat distribution system inside the dwelling able to work at low or more efficient temperature levels? | This is a new data field, present in BERs from May 24th, 2026. For BERs published before that date, this value must be confirmed in the onsite survey. For BERs published before that date, the value can be re-used, even where evidence supporting this data is not available |
| Data Entry Item | Guidance on re-use of data | Notes and examples |
|---|---|---|
| Central heating pump | Information on the central heating pump, - Number present, - Boiler Controlled by Room Thermostat, - Inside Dwelling, must be confirmed in the onsite survey and any errors must be corrected. For the Electricity Consumption, non-default data may be re-used, even where evidence supporting this data is not available. |
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| Oil boiler fuel pumps | Information on oil boiler fuel pumps, - Number present, - Boiler Controlled by Room Thermostat, - Inside Dwelling, must be confirmed in the onsite survey and any errors must be corrected. |
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| Gas boiler flue fan | Information on gas boiler flue fans must be confirmed in the onsite survey, and any error must be corrected. | |
| Warm air heating or fan coil radiators present? | Information on warm air heating systems must be confirmed in the onsite survey, and any errors must be corrected. |
| Data Entry Item | Guidance on re-use of data | Notes and examples |
|---|---|---|
| Main space heating system efficiency |
Information on the main space and water heating systems must be confirmed in the onsite survey, and any errors must be corrected. Non-default space heating system efficiency data may be re-used, even where evidence supporting this data is not available. For heat pumps, the following non-default data may be re-used, even where evidence supporting this data is not available: - Space heating efficiency data (Ecodesign data) - Design Flow Temperature - Daily Operation (hours) For heat pumps, the presence of any Backup Heating System - for Space Heating and/or Water Heating – must be confirmed in the onsite survey, and any errors must be corrected. |
Where it is possible to identify the heating system model onsite, it should be checked against the model referenced in the assessment. If the models do not match, the data should not be re-used. |
| Secondary heating system | Information on secondary heating systems must be confirmed in the onsite survey, and any errors must be corrected. Non-default heating system efficiency data may be re-used, even where evidence supporting this data is not available. |
Where the heating system model referenced in the assessment does not match the model found onsite, data should not be re-used. |
| Fuel data | Information on heating system fuels must be confirmed in the onsite survey, and any errors must be corrected. | |
| Group heating scheme | Information on group heating systems must be confirmed in the onsite survey, and any errors must be corrected. The following non-default group heating system data may be re-used: - Fuel, - Percentage of Heat, - Efficiency, even where evidence supporting this data is not available. |
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| District heating scheme | Information on district heating systems must be confirmed in the onsite survey, and any errors must be corrected. Non-default district heating system efficiency data may be re-used, even where evidence supporting this data is not available. |
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| Heat loss from heat distribution system outside the dwelling [kWh/yr] | Information on the distribution losses for group or district heating schemes must be confirmed in the onsite survey, and any errors must be corrected. A value from a previous BER may be re-used, even where evidence supporting this data is not available. |
This is a new data field, present in BERs with group heating published from May 24th, 2026 on. |
| Combined Heat and Power (CHP) for group or individual heating system. | Information on CHP systems must be confirmed in the onsite survey, and any errors must be corrected. Non-default data for CHP systems may be re-used, even where evidence supporting this data is not available. |
| Data Entry Item | Guidance on re-use of data | Notes and examples |
|---|---|---|
| Storage losses | Information on storage losses in the water heating system must be confirmed in the onsite survey, and any errors must be corrected. | |
| Storage indoors or in group heating scheme | Information on storage losses in the water heating system must be confirmed in the onsite survey, and any errors must be corrected. | |
| Manufacturers declared loss available | The re-use of non-default data is allowed for storage losses, even where evidence supporting this data is not available. | |
| Distribution losses | Information on distribution losses in the water heating system must be confirmed in the onsite survey, and any errors must be corrected. | |
| Supplementary electric water heating in summer | Information on the need for supplementary electric water heating in summer must be confirmed in the onsite survey, and any error must be corrected. | |
| Storage type | Information on the water heating storage type must be confirmed in the onsite survey, and any error must be corrected. | |
| Storage volume | Information on water storage volume must be confirmed in the onsite survey, and any errors must be corrected. The re-use of non-default data is allowed for storage volume, even where evidence supporting this data is not available. |
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| Heat pump type of DHW | Where a heat pump is present providing hot water, the type of water storage must be confirmed in the onsite survey, and any errors must be corrected. | |
| Storage temperature factors | Information on temperature factors, which are based on the presence of the following controls for the hot water system, - Cylinder thermostat, - Cylinder Heated by Boiler / Heat Pump system having separate time control of DHW, - Separate timer for heating the store, - Store in an airing cupboard, must be confirmed in the onsite survey and any errors must be corrected. |
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| Insulation type and thickness of the water storage volume | Information on water storage insulation type and thickness must be confirmed in the onsite survey, and any errors must be corrected. The re-use of non-default data is allowed for storage volume, even where evidence supporting this data is not available. |
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| Make and model, Declared Loss | The re-use of non-default data is allowed for storage losses, even where evidence supporting this data is not available. | |
| Primary circuit loss type | Information on the factors affecting the primary circuit loss type must be confirmed in the onsite survey and any errors must be corrected, e.g. where relevant and possible check that the visible primary pipework is fully insulated. |
| Data Entry Item | Guidance on re-use of data | Notes and examples |
|---|---|---|
| Is there a combi boiler | The presence of a combi boiler must be confirmed in the onsite survey, and any errors must be corrected. | |
| Combi Boiler Type | Combi boiler type must be confirmed in the onsite survey, and any errors must be corrected. | |
| Electric Keep-hot Facility Type | Electric Keep-hot Facility Type must be confirmed in the onsite survey, and any errors must be corrected. The re-use of non-default data is allowed for this entry, even where evidence supporting this data is not available. |
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| Additional Loss | The Additional Combi Loss must be confirmed based on the combi parameters, and any errors must be corrected. The re-use of non-default data is allowed for Additional Loss, even where evidence supporting this data is not available |
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| Keep-hot Consumption | The Keep-hot Consumption must be confirmed based on the combi parameters, and any errors must be corrected. The re-use of non-default data is allowed for the Keep-hot Consumption, even where evidence supporting this data is not available. |
| Data Entry Item | Guidance on re-use of data | Notes and examples |
|---|---|---|
| Bath: Number of Items | This entry must be confirmed and any error corrected. | BERs published using DEAP 3 will need to be updated, as baths and showers were not recorded in DEAP 3. |
| Bath: Description | This is an editable field and can be overwritten as necessary as it does not affect the BER. | BERs published using DEAP 3 will need to be updated, as baths and showers were not recorded in DEAP 3. |
| Shower: Number of Items | This entry must be confirmed and any error corrected. | BERs published using DEAP 3 will need to be updated, as baths and showers were not recorded in DEAP 3. |
| Shower type | This entry must be confirmed and any error corrected. | BERs published using DEAP 3 will need to be updated, as baths and showers were not recorded in DEAP 3. |
| Shower: Description | This is an editable field and can be overwritten as necessary as it does not affect the BER. | BERs published using DEAP 3 will need to be updated, as baths and showers were not recorded in DEAP 3. |
| Flow Restrictor | This presence of a flow restrictor must be confirmed and any error corrected. The re-use of non-default data is allowed for storage volume, even where evidence supporting this data is not available. |
BERs published using DEAP 3 will need to be updated, as baths and showers were not recorded in DEAP 3. |
| Flow Rate | The re-use of a non-default Flow Rate is allowed for showers, even where evidence supporting this data is not available. | BERs published using DEAP 3 will need to be updated, as baths and showers were not recorded in DEAP 3. |
| Waste Water Heat Recovery Efficiency | The re-use of a non-default WWHR Efficiency is allowed for showers, even where evidence supporting this data is not available. | BERs published using DEAP 3 will need to be updated, as baths and showers were not recorded in DEAP 3. |
| Waste Water Heat Recovery Utilisation Factor | The re-use of a non-default WWHR Utilisation Factor is allowed for showers, even where evidence supporting this data is not available. | BERs published using DEAP 3 will need to be updated, as baths and showers were not recorded in DEAP 3. |
| Data Entry Item | Guidance on re-use of data | Notes and examples |
|---|---|---|
| Solar thermal panels | Information on the presence of solar thermal panels must be confirmed in the onsite survey, and any errors must be corrected. | |
| Aperture area of solar panels. | The re-use of non-default values is allowed for solar panel efficiency data, even where evidence supporting this data is not available. | |
| Zero loss collector efficiency | The re-use of non-default values is allowed for solar panel efficiency data, even where evidence supporting this data is not available. | |
| Collector heat loss coefficient | The re-use of non-default values is allowed for solar panel efficiency data, even where evidence supporting this data is not available. | |
| Dedicated solar storage | Information on dedicated solar storage volume must be confirmed in the onsite survey, and any errors must be corrected. The re-use of non-default data is allowed for dedicated solar storage volume, even where evidence supporting this data is not available. |
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| Annual solar radiation: over shading, orientation, and tilt | Information on the factors affecting the annual solar radiation falling on solar thermal panels, i.e. - Orientation, - Tilt In Degrees From Horizontal, - Overshading, must be confirmed in the onsite survey and any errors must be corrected. |
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| Cylinder Stat | The presence of a cylinder thermostat must be confirmed in the onsite survey, and any error must be corrected. | |
| Pump Solar Powered | The presence of a solar powered pump must be confirmed in the onsite survey, and any error must be corrected. | |
| Storage Contained within a combined Cylinder | The presence of a combined cylinder must be confirmed in the onsite survey, and any error must be corrected. |
For water heat source, see approach for entries under “space heating” tab above. Data is entered separately for water heating source if not the same as space heating source.
| Data Entry Item | Guidance on re-use of data | Notes and examples |
|---|---|---|
| Fixed cooling system | The presence of a cooling system must be confirmed in the onsite survey, and any errors must be corrected. | This is now set default of 2.5. |
| Data Entry Item | Guidance on re-use of data | Notes and examples |
|---|---|---|
| Lighting Design Unknown | As of May 24th, 2026, the case where Lighting Design is Unknown no longer requires a data entry. | The lighting section will need to be updated by toggling the Lighting Design to ‘Known’, then back to ‘Unknown’. |
| Lighting Design known (Lighting design information) | The re-use of non-default data is allowed for lighting, even where evidence the detailed lighting design is not available. |
| Data Entry Item | Guidance on re-use of data | Notes and examples |
|---|---|---|
| Solar PV | Data entry for Solar PV changed on May 24th, 2026, so for any BERs with PV published before that date, the data will have to be re-entered. For BERs published on or after that date, non-default data for solar PV systems may be re-used. |
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| Wind turbines | Data entry for Wind turbines changed on May 24th, 2026, so for any BERs with wind turbines published before that date, the data will have to be re-entered. For BERs published on or after that May 24th, 2026, non-default data for wind turbine systems may be re-used. |
To re-use data from a previous installation, set "Annual Output is Known” to ‘Yes’, and enter the previously calculated value into the “Annual Output”. |
| Other Renewables | Data from the Other Renewables section may be re-used, even where evidence supporting this data is not available. |
| Data Entry Item | Guidance on re-use of data | Notes and examples |
|---|---|---|
| Assessment of whether fossil fuel is used on site | The presence of a fossil fuel heating system must be confirmed in the onsite survey, and any error must be corrected. | This is a new data field for BERs published from May 24th, 2026 on. |
| Ability to adapt energy use, generation or storage according to external signals | The entry must be confirmed in the onsite survey, and any error must be corrected. | This is a new data field for BERs published from May 24th, 2026 on. |
| Data Entry Item | Guidance on re-use of data | Notes and examples |
|---|---|---|
| Value of Lifecycle of GWP | Non-default data for this entry may be re-used, even where evidence supporting this data is not available. | This is a new data field for BERs published from May 24th, 2026 on. |