Welcome to the new DEAP Guidance website.
This website contains guidance for the Dwelling Energy Assessment Procedure (DEAP), which is Ireland’s official method for calculating and rating the energy performance of dwellings. This version of the DEAP guidance is applicable to Building Energy Ratings for new and existing dwellings from 24th of May 2026.
This website replaces the DEAP Manual, the DEAP Survey Guide, and the DEAP Guidance Document.
It is designed to replicate the layout of the DEAP v4.3 software and contains all the calculation and surveying requirements necessary to complete a BER Assessment, along with examples covering various scenarios likely to be encountered onsite.
In moving the DEAP guidance to this website, it has been necessary to re-number the tables used throughout DEAP.
To help you find them more easily, the most commonly used tables are listed here with links to their new location.
| Previous table number | Description | New table number |
|---|---|---|
| Table E4 | Efficiency conversion factors | Table 4.32 |
| Table S1 | Age bands | Table 2.7 |
| Table S2 | Building regulations summary | Table 2.8 |
| Table S3 | Exposed wall U-values | Table 2.21 |
| Table S3a | U-values of semi-exposed uninsulated walls between apartment and unheated corridor | Table 2.22 |
| Table S3b | Exposed wall U-Values with typical drylining insulation upgrades | Table 2.23 |
| Table S3c | Default building element U-values using onsite verification indicators | Table 2.24 |
| Table S3d | Deriving wall U-values: summary | Table 2.25 |
| Table S4 | Roof U-values when loft insulation thickness is known | Table 2.16 |
| Table S5 | Assumed U-values when the roof insulation thickness is unknown | Table 2.17 |
| Table S6 | Basis for floor U-value calculation | Table 2.11 |
| Table S7 | Exposed/Semi-exposed floor U-values | Table 2.14 |
| Table S8 | Summary of floor U-value defaults | Table 2.13 |
| Table S9 | Default window values based on Age | Table 2.35 |
| Table S10 | Thermal mass category defaults | Table 2.43 |
| Table S12 | Data to be collected | Table 1.4 |
| Table 2 | Factors to be applied to losses for cylinders, thermal stores and CPSUs | Table 5.1 |
| Table 2a | Calculation of hot water storage vessel volume | Table 5.2 |
| Table 3 | Primary Circuit Losses | Table 5.3 |
| Table 3a | Additional losses for combi boilers | Table 5.4 |
| Table 4a | Heating system seasonal efficiency (space and water) | Table 4.4 |
| Table 4b | Gross seasonal efficiency for gas and oil boilers | Table 4.5 |
| Table 4c | Efficiency adjustment factors | Table 4.6 |
| Table 4d | Heating responsiveness category for wet systems | Table 4.7 |
| Table 4e | Heating system controls | Table 4.8 |
| Table 4f | Electricity for fans and pumps and electric keep-hot facility | Table 4.9 |
| No previous number | Electricity for pumps based on Energy Label category | Table 4.10 |
| Table 4g | Specific fan power for mechanical ventilation systems | Table 3.7 |
| Table 6a | Default U-values for windows, doors and roof windows. | Table 2.28 |
| No previous number | U-value adjustment for roof window with wood or PVC frames | Table 2.29 |
| No previous number | U-value adjustment for roof window with metal frames | Table 2.30 |
| Table 6b | Solar transmittance and light transmittance of glazing types | Table 2.31 |
| Table 6c | Frame factors for windows and glazed doors | Table 2.32 |
| Table 6d | Solar and light access factors | Table 2.33 |
| Table 7 | Fraction of heat supplied by secondary heating systems | Table 4.14 |
| Table 8 | Fuel data | Table 12.1 |
| Table 11 | Thermal mass categories for the dwelling | Table 2.41 |
| Table 11a | Thermal Mass of construction elements | Table 2.42 |
| Table 12a | Thermal conductivity of some common building materials | Table 2.9 |
| Table 12b | Thermal conductivity of some common insulation materials | Table 2.10 |