| Floor type | P/A Ratio | A | B | C | D | E | F | G | H | I | J | K | L |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Ground floor - solid | 0.1 | 0.27 | 0.27 | 0.27 | 0.27 | 0.27 | 0.23 | 0.23 | 0.19 | 0.19 | 0.17 | 0.14 |
0.21
|
| 0.2 | 0.46 | 0.46 | 0.46 | 0.46 | 0.46 | 0.38 | 0.38 | 0.29 | 0.29 | 0.26 | 0.19 | ||
| 0.3 | 0.61 | 0.61 | 0.61 | 0.61 | 0.61 | 0.48 | 0.48 | 0.36 | 0.36 | 0.31 | 0.22 | ||
| 0.4 | 0.73 | 0.73 | 0.73 | 0.73 | 0.73 | 0.57 | 0.57 | 0.41 | 0.41 | 0.34 | 0.24 | ||
| 0.5 | 0.84 | 0.84 | 0.84 | 0.84 | 0.84 | 0.64 | 0.64 | 0.44 | 0.44 | 0.37 | 0.25 | ||
| 0.6 | 0.94 | 0.94 | 0.94 | 0.94 | 0.94 | 0.7 | 0.7 | 0.47 | 0.47 | 0.39 | 0.26 | ||
| 0.7 | 1.02 | 1.02 | 1.02 | 1.02 | 1.02 | 0.74 | 0.74 | 0.49 | 0.49 | 0.4 | 0.27 | ||
| 0.8 | 1.1 | 1.1 | 1.1 | 1.1 | 1.1 | 0.79 | 0.79 | 0.51 | 0.51 | 0.42 | 0.27 | ||
| 0.9 | 1.16 | 1.16 | 1.16 | 1.16 | 1.16 | 0.82 | 0.82 | 0.52 | 0.52 | 0.43 | 0.28 | ||
| 1 or more | 1.23 | 1.23 | 1.23 | 1.23 | 1.23 | 0.85 | 0.85 | 0.54 | 0.54 | 0.44 | 0.28 | ||
| Ground floor - suspended | 0.1 | 0.27 | 0.27 | 0.27 | 0.27 | 0.27 | 0.25 | 0.25 | 0.22 | 0.22 | 0.2 | 0.17 |
0.21 |
| 0.2 | 0.44 | 0.44 | 0.44 | 0.44 | 0.44 | 0.39 | 0.39 | 0.32 | 0.32 | 0.28 | 0.22 | ||
| 0.3 | 0.56 | 0.56 | 0.56 | 0.56 | 0.56 | 0.48 | 0.48 | 0.37 | 0.37 | 0.33 | 0.24 | ||
| 0.4 | 0.65 | 0.65 | 0.65 | 0.65 | 0.65 | 0.55 | 0.55 | 0.42 | 0.42 | 0.36 | 0.26 | ||
| 0.5 | 0.73 | 0.73 | 0.73 | 0.73 | 0.73 | 0.6 | 0.6 | 0.45 | 0.45 | 0.38 | 0.27 | ||
| 0.6 | 0.8 | 0.8 | 0.8 | 0.8 | 0.8 | 0.64 | 0.64 | 0.47 | 0.47 | 0.4 | 0.28 | ||
| 0.7 | 0.85 | 0.85 | 0.85 | 0.85 | 0.85 | 0.68 | 0.68 | 0.49 | 0.49 | 0.41 | 0.28 | ||
| 0.8 | 0.9 | 0.9 | 0.9 | 0.9 | 0.9 | 0.71 | 0.71 | 0.50 | 0.50 | 0.42 | 0.29 | ||
| 0.9 | 0.94 | 0.94 | 0.94 | 0.94 | 0.94 | 0.73 | 0.73 | 0.52 | 0.52 | 0.43 | 0.29 | ||
| 1 or more | 0.98 | 0.98 | 0.98 | 0.98 | 0.98 | 0.76 | 0.76 | 0.53 | 0.53 | 0.44 | 0.30 | ||
| Ground floor – above unheated basement | 0.1 | 0.56 | 0.56 | 0.56 | 0.56 | 0.56 | 0.47 | 0.47 | 0.36 | 0.36 | 0.31 | 0.22 | 0.21 |
| 0.2 | 0.75 | 0.75 | 0.75 | 0.75 | 0.75 | 0.60 | 0.60 | 0.43 | 0.43 | 0.36 | 0.25 | ||
| 0.3 | 0.88 | 0.88 | 0.88 | 0.88 | 0.88 | 0.68 | 0.68 | 0.47 | 0.47 | 0.39 | 0.26 | ||
| 0.4 | 0.98 | 0.98 | 0.98 | 0.98 | 0.98 | 0.73 | 0.73 | 0.50 | 0.50 | 0.41 | 0.27 | ||
| 0.5 | 1.06 | 1.06 | 1.06 | 1.06 | 1.06 | 0.78 | 0.78 | 0.51 | 0.51 | 0.42 | 0.28 | ||
| 0.6 | 1.12 | 1.12 | 1.12 | 1.12 | 1.12 | 0.81 | 0.81 | 0.53 | 0.53 | 0.43 | 0.28 | ||
| 0.7 | 1.17 | 1.17 | 1.17 | 1.17 | 1.17 | 0.84 | 0.84 | 0.54 | 0.54 | 0.44 | 0.28 | ||
| 0.8 | 1.21 | 1.21 | 1.21 | 1.21 | 1.21 | 0.86 | 0.86 | 0.55 | 0.55 | 0.44 | 0.29 | ||
| 0.9 | 1.26 | 1.26 | 1.26 | 1.26 | 1.26 | 0.88 | 0.88 | 0.56 | 0.56 | 0.45 | 0.29 | ||
| 1 or more | 1.29 | 1.29 | 1.29 | 1.29 | 1.29 | 0.89 | 0.89 | 0.56 | 0.56 | 0.45 | 0.29 | ||
| Floor type | P/A Ratio | A | B | C | D | E | F | G | H | I | J | K | L |
| Basement – heated | 0.1 | 0.36 | 0.36 | 0.36 | 0.36 | 0.36 | 0.29 | 0.29 | 0.22 | 0.22 | 0.2 | 0.15 | 0.21 |
| 0.2 | 0.54 | 0.54 | 0.54 | 0.54 | 0.54 | 0.42 | 0.42 | 0.31 | 0.31 | 0.27 | 0.19 | ||
| 0.3 | 0.65 | 0.65 | 0.65 | 0.65 | 0.65 | 0.49 | 0.49 | 0.35 | 0.35 | 0.3 | 0.21 | ||
| 0.4 | 0.73 | 0.73 | 0.73 | 0.73 | 0.73 | 0.54 | 0.54 | 0.38 | 0.38 | 0.32 | 0.22 | ||
| 0.5 | 0.78 | 0.78 | 0.78 | 0.78 | 0.78 | 0.57 | 0.57 | 0.4 | 0.4 | 0.33 | 0.23 | ||
| 0.6 | 0.81 | 0.81 | 0.81 | 0.81 | 0.81 | 0.59 | 0.59 | 0.41 | 0.41 | 0.34 | 0.24 | ||
| 0.7 | 0.84 | 0.84 | 0.84 | 0.84 | 0.84 | 0.6 | 0.6 | 0.42 | 0.42 | 0.35 | 0.24 | ||
| 0.8 | 0.86 | 0.86 | 0.86 | 0.86 | 0.86 | 0.62 | 0.62 | 0.42 | 0.42 | 0.35 | 0.24 | ||
| 0.9 | 0.87 | 0.87 | 0.87 | 0.87 | 0.87 | 0.63 | 0.63 | 0.43 | 0.43 | 0.36 | 0.24 | ||
| 1 or more | 0.89 | 0.89 | 0.89 | 0.89 | 0.89 | 0.63 | 0.63 | 0.43 | 0.43 | 0.36 | 0.24 | ||
| Partially heated below | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | |
| Exposed / semi exposed | 1.2 | 1.2 | 1.2 | 1.2 | 1.2 | 1.2 | 1.2 | 1.2 | 1.2 | 1.2 | 1.2 | 1.2 | |
| Other | No default data | ||||||||||||
Ground-floor – above unheated basement: This U-value is for the ground floor between the dwelling and unheated basement. Underground open car parks would not be considered to be unheated basements. The actual basement floor is assumed to be uninsulated. Perimeter is the exposed perimeter of that ground floor and area is the area of that ground floor. Insulation thickness as outlined. Insulation thickness and conductivity as per solid floors for same age band.
Basement – heated: This U-value applies to the heated basement walls and floor. Insulation in walls and floor assumed to be of thickness and conductivity as per solid floors. When determining default U-values for heated basements in existing dwellings the following rules apply:
A heated basement is considered as part of the dwelling volume in DEAP when the criteria in Section 1 (dimensions) are met. The heated basement floor and walls are considered to be heat loss elements in DEAP. The ground floor (which is also the heated basement ceiling) is an internal non-heat loss element.
For P/A ratio of the basement for default U-value calculation:
To simplify data collection, there is no distinction in terms of U-value between an exposed floor (to outside air below) and a semi-exposed floor (to an enclosed but unheated space below) and the U-values in Table 2.7 are used (based on Building Regulations Table S2).
Table 2.14 (formerly Table S7) - Exposed/Semi-exposed floor U-values
| Age band | U-value (W/m²K) |
|---|---|
| A to E | 1.20 |
| F, G | 0.8 |
| H, I | 0.6 |
| J | 0.37 |
| K | 0.25 |
| L | 0.21 |
The U-value of a floor above partially heated premises is taken as 1.0 W/m²K. This applies typically for a flat above non-domestic premises that are not heated to the same extent or duration as the flat.
Where an existing dwelling is above a space heated to a different pattern than that of a dwelling, then the default U-value of 1.0 W/m2K applies. This is half of a typical value for an uninsulated exposed element. However, if there is enough information available (and proof thereof) to calculate the actual floor U-value, then this should be done, and the result halved as to attain the floor U-value.