Sprouto/rdsap10 huggingface dataset:
a) Detailed assessment option for RR:
Where all actual dimensions are measured, and the U-values assigned; see section 4.10, and Figure 4 for the details.  
The U-value are from Table 4 : U-values of gable-end and other walls in RR.
a) Detailed assessment option for RR:
b) Simplified assessment option for RR:
Slightly less accurate but requiring less measurements.
The simplified assessment option has two scenarios:  
1) Room in Roof fully within roof (true Room in Roof), and
2) Room in Roof built into a roof space which has continuous common walls located outside of the RR boundaries.
4.9.1 The approach to Room in Roof fully within roof (True Room in Roof), see also 2.16:
![img-4.jpeg](img_ref_5)  
There is no common wall in the true RR type, therefore 1.8 m rule does not apply.
a) Detailed assessment option for RR:
The following steps apply when:
RR is either:
-RR fully within the roof (left diagram above), or
-RR type with accessible areas of continuous common walls which are outside the boundaries of the RR (right diagram above).
a) Assessor measures floor dimensions in $m$ (length $\mathrm{L}_{\text {RR_floor }}$ and width $\mathrm{W}_{\text {RR_floor }}$ ) and calculates RR floor area $A_{R R \_f l o o r}$
$A_{R R \_f l o o r}=L_{R R \_f l o o r} \times W_{R R \_f l o o r}$
b) The height of $R R$ is assumed to be $\mathbf{2 . 2} \mathbf{m}$ high (this is lower than normal room height of 2.4 m to compensate for the sloping parts); however, this height does not include $\mathbf{0 . 2 5 m}$ between $R R$ and the storey below, therefore 0.25 m needs to be added, making height of RR $2.2+0.25=2.45 \mathrm{~m}$.
a) Detailed assessment option for RR:
The following steps apply when:
In addition, if applicable, assessor measures and specifies length of each gable ( $\mathrm{L}_{\text {gable1 }}$ and $\mathrm{L}_{\text {gable2 }}$ ) or adjacent wall ( $A_{R R \_p a r t y}, A_{R R \_s h e l t e r e d}$ or $A_{R R \_c o n n e c t e d}$ ) and software assumes height of gables as 2.45 m (this also includes 0.25 m between RR and the storey below).
c) The areas of the applicable RR walls are calculated by software as:
$\sum A_{R R \_g a b l e / o t h e r}=A_{R R \_g a b l e 1}+A_{R R \_g a b l e 2}+A_{R R \_p a r t y}+A_{R R \_s h e l t e r e d}+A_{R R \_c o n n e c t e d}$
Where for the gable walls:  
$$
\begin{aligned}
& A_{R R \_g a b l e 1}=L_{\text {gable } 1} \times 2.45 \mathrm{~m} \\
& A_{R R \_g a b l e 2}=L_{\text {gable } 2} \times 2.45 \mathrm{~m}
\end{aligned}
$$  
For other walls (party walls, sheltered walls or walls connected to another part or the dwelling):  
$$
\begin{aligned}
& A_{R R \_ \text {party }}=L_{\text {party }} \times 2.45 \mathrm{~m} \\
a) Detailed assessment option for RR:
The following steps apply when:
$$  
For other walls (party walls, sheltered walls or walls connected to another part or the dwelling):  
$$
\begin{aligned}
& A_{R R \_ \text {party }}=L_{\text {party }} \times 2.45 \mathrm{~m} \\
& A_{R R \_ \text {sheltered }}=L_{\text {sheltered }} \times 2.45 \mathrm{~m} \\
& A_{R R \_ \text {connected }}=L_{\text {connected }} \times 2.45 \mathrm{~m}
\end{aligned}
$$  
Note: Heights of these walls are not measured by assessors; they are assumed as 2.45 m .
d) The remaining RR area is assessed by using the equation (this includes gable walls):  
$$
A_{R R}=12.5 \sqrt{A_{R R_{-} \text {floor }} / 1.5}
$$  
This is treated as timber framed construction and assumes a rectangular room-in-roof area of average height 2.2 m , and accounts for 0.25 m between RR floor and the ceiling of the storey below, i.e. the calculation uses RR height $=(2.2+0.25)=2.45 \mathrm{~m}$.
e) The areas of gable walls are deducted from the net RR area is:  
$$
a) Detailed assessment option for RR:
The following steps apply when:
e) The areas of gable walls are deducted from the net RR area is:  
$$
A_{R R \_ \text {final }}=A_{R R}-\sum A_{R R \_ \text {gable/other }}
$$  
The rest of the calculation is as normal, i.e. software will treat $A_{R R}$ final as timber framed construction, and gables will be allocated U-values given in Table 4.  
Table 4Note: different U-values should be assigned to gable and adjacent walls with different heatloss; therefore, there are four options for gable walls:  
Table 4 : U-values of gable-end and other walls in RR  
| Description | RR wall type | Assigned U-value |
| :-- | :-- | :-- |
| $A_{R R \text {, gable }}$ | Exposed gable | U-value as common wall |
| $A_{R R \text {, party }}$ | Party | U-value $=0.25 \mathrm{~W} / \mathrm{m} 2 \mathrm{~K}$ |
| $A_{R R \text {, sheltered }}$ | Sheltered | U-value as external wall with sheltering factor $\mathrm{R}=0.5$ |
| $A_{R R \text {, connected }}$ | Adjacent to heated <br> space | U-value $=0$ |
a) Detailed assessment option for RR:
The following steps apply when:
| $A_{R R \text {, sheltered }}$ | Sheltered | U-value as external wall with sheltering factor $\mathrm{R}=0.5$ |
| $A_{R R \text {, connected }}$ | Adjacent to heated <br> space | U-value $=0$ |  
f) Elements of RR other than gable-end and adjacent walls are assumed by software to be of a timber framed construction with U-values from Table 17 or Table 18
4.9.2 The approach to RR Type with the accessible areas of continuous common walls
(see also section 2.16):
![img-5.jpeg](img_ref_6)  
This type of RR is checked for the 1.8 m rule. It is considered as Room in Roof when the height of accessible common walls is less than 1.8 m (otherwise it is a separate storey).  
The following applies when:
RR has accessible areas of continuous common walls which are boundaries of the RR; this RR type is as defined in Figure 2 (see section 2.16.2).  
The approach is:
a) Assessor measures floor dimensions (length $\mathrm{L}_{\text {RR_floor }}$ and width $\mathrm{W}_{\text {RR_floor }}$ ) and calculates RR floor area $\mathrm{A}_{\text {RR_floor }}$  
$$
\mathrm{A}_{\text {RR_floor }}=\mathrm{L}_{\text {RR_floor }} \times \mathrm{W}_{\text {RR_floor }}
$$  
In addition, the following applicable dimensions are measured:
4.9.2 The approach to RR Type with the accessible areas of continuous common walls
$$
\mathrm{A}_{\text {RR_floor }}=\mathrm{L}_{\text {RR_floor }} \times \mathrm{W}_{\text {RR_floor }}
$$  
In addition, the following applicable dimensions are measured:  
- length of each gable or adjacent wall ( $\mathrm{L}_{\text {gable1 }}, \mathrm{L}_{\text {gable2 }}, \mathrm{L}_{\text {party, }} \mathrm{L}_{\text {sheltered or }} \mathrm{L}_{\text {, connected }}$ ) and their heights ( $\mathrm{H}_{\text {gable1 }}, \mathrm{H}_{\text {gable2 }}, \mathrm{H}_{\text {party, }} \mathrm{H}_{\text {sheltered or }} \mathrm{H}_{\text {connected }}$ ) where heights are measured at the highest point of each accessible gable or adjacent wall;
- length $\mathrm{L}_{\text {common_wall }}$ and height $\mathrm{H}_{\text {common_wall }}$ of each accessible common wall;
a) The total area of each continuous common wall is calculated as:
$A_{R R \text { _common_wall }}=\Sigma\left(L_{\text {common_wall }} \times\left(0.25+H_{\text {common_wall }}\right)\right.$
4.9.2 The approach to RR Type with the accessible areas of continuous common walls
a) The total area of each continuous common wall is calculated as:
$A_{R R \text { _common_wall }}=\Sigma\left(L_{\text {common_wall }} \times\left(0.25+H_{\text {common_wall }}\right)\right.$
b) Software calculates the area of each gable or adjacent wall by using the equation:  
$$
A_{R R_{-} \text {gable }}=L_{\text {gable }} \times\left(0.25+H_{\text {gable }}\right)-\left(\frac{\left(H_{\text {gable }}-H_{\text {common_wall_1 }}\right)^{2}}{2}+\frac{\left(H_{\text {gable }}-H_{\text {common_wall_2 }}\right)^{2}}{2}\right)
$$  
Note: 0.25 m added to the measured height of common wall to take account space of 0.25 m between $R R$ and the storey below.
$\mathrm{A}_{\mathrm{RR} \text {_gable }}$ can be one of the appropriate values in Table 4 : U-values of gable-end and other walls in RR
4.9.2 The approach to RR Type with the accessible areas of continuous common walls
$\mathrm{A}_{\mathrm{RR} \text {_gable }}$ can be one of the appropriate values in Table 4 : U-values of gable-end and other walls in RR  
The same equation is used for calculating areas of other walls, where a gable wall is a party wall ( $\mathrm{A}_{\text {RR_party }}$ ), a sheltered wall ( $\mathrm{A}_{\text {RR_sheltered }}$ ) or a wall connected to another building part (ARR, connected).  
These walls will be assigned to $U$-values given in Table 4.
Walls other than gable-end walls, adjacent walls and accessible continuous common walls are assumed to be of a timber framed construction with U-values from Table 17 : U-values applicable to rooms in roof (RR) where insulation thickness is known.
c) Total RR wall area is calculated by the equation (this includes gables and accessible continuous walls):  
$$
A_{R R}=12.5 \sqrt{A_{R R_{-} \text {floor }} / 1.5}
$$
4.9.2 The approach to RR Type with the accessible areas of continuous common walls
c) Total RR wall area is calculated by the equation (this includes gables and accessible continuous walls):  
$$
A_{R R}=12.5 \sqrt{A_{R R_{-} \text {floor }} / 1.5}
$$  
d) The areas of gable walls are deducted from the calculated total RR area, and the remaining area of $R R, A_{R R \text { _final }}$ is then calculated. This area is treated as roof structure.
$\mathrm{A}_{\mathrm{RR} \text { _final }}=\mathrm{A}_{\mathrm{RR} \text { _wall }}-\left(\sum \mathrm{A}_{\mathrm{RR} \text { common_wall }}+\sum \mathrm{A}_{\mathrm{RR} \text { gable }}+\sum \mathrm{A}_{\mathrm{RR} \text { party }}+\sum \mathrm{A}_{\mathrm{RR} \text { sheltered }}+\sum \mathrm{A}_{\mathrm{RR} \text { connected }}\right)$.
e) The rest of the calculation is as normal, i.e. software will treat $\mathrm{A}_{\text {RR_final }}$ as timber framed construction, and other elements (continuous common walls and gables) will be treated by allocating the appropriate $U$-value.
4.9.2 The approach to RR Type with the accessible areas of continuous common walls
Note: 0.25 m between RR and the storey below is added by software (not by RdSAP Assessor).
4.10 Detailed measurements of roof room
Detailed measurements of roof rooms are required only if evidence exists that the flat ceiling, slope, stud wall (or common wall) or gable wall (see Figure 4) have differing levels of insulation and each of their Uvalues is known. Refer to RdSAP Conventions for more details.
![img-6.jpeg](img_ref_7)  
Figure 4: Different parts of roof rooms
(instead of stud wall and residual ceiling there can be a common wall)  
For detailed measurements of roof rooms there can be up to two of each of:  
- flat ceiling
- sloping ceiling
- stud wall (or common wall)
- gable wall  
A U-value must be acquired for each non-zero heat loss area.
4.10 Detailed measurements of roof room
4.10.1 Default U-values of the roof rooms.
Where the details of insulation are not available, the default $U$-values are those for the appropriate age band for the construction of the roof rooms (see Table 18 : Assumed roof U-values when Table 16 or Table 17 do not apply). The default $U$-values apply when the roof room insulation is 'as built' or 'unknown'.  
Where the thickness of insulation of the roof room elements has been determined, the U-value is from Table 16 : Roof U-values when loft insulation thickness is known or the insulation thickness concerned and for the insulation type, except for a vaulted roof when the insulation of the flat ceiling is marked as 'not applicable' and for the purposes of the calculation $U_{R R}=U_{v t}$ ( $U_{R R}$ means Room Roof $U$-value and $U_{v t}$ means $U$-value of vaulted roof).
4.10 Detailed measurements of roof room
4.10.1 Default U-values of the roof rooms.
The residual area (area of roof less the floor area of room(s)-in-roof) has a U-value from Table 16 : Roof U-values when loft insulation thickness is known according to its insulation thickness if at least half the area concerned is accessible, otherwise it is the default for the age band of the original property or extension.  
The default U-value can be overwritten if any of the elements of the roof room (ceiling/slope/stud/gable) have known insulation details and the U -values are available or taken from the Tables in this document on a basis of the type and thickness of insulation.
4.10 Detailed measurements of roof room
4.11 Heat loss area for houses and bungalows
The lowest floor of a part of a dwelling ('part' means main dwelling or any extension) can be a basement, a ground floor, an exposed floor (external air below e.g. over a passageway) or a semi-exposed floor (unheated space below e.g. over an integral garage) or not a heat loss floor (upper flats/maisonettes or same or another dwelling below).  
The area of the lowest occupied floor of the main dwelling is a ground floor.
If it is a heated basement it is treated as a lowest occupied floor.
For each building part examine the floor areas on each storey. If the area of any upper floor is greater than that of the floor below, the difference in these areas is an exposed or semi-exposed floor. Exposed floors are ground floors or floors above a passage. An example of semi-exposed floor is a floor above an integral garage.
4.10 Detailed measurements of roof room
4.11 Heat loss area for houses and bungalows
When external dimensions are being used, however, the method of dimensional conversion can result in a small, but spurious, exposed floor area. To avoid that situation, the area of exposed floor on any level cannot be greater than the difference between the area of the current floor and the floor below measured using external dimensions.  
This rule is implemented as follows:  
1. Calculate the exposed floor area before converting dimensions, call this $\mathrm{A}_{1}$
2. Convert dimensions
3. Calculate exposed floor area from the internal areas, call this $\mathrm{A}_{2}$
4. If $\mathrm{A}_{2} \leq \mathrm{A}_{1}$ the exposed floor area is $\mathrm{A}_{2}$
5. If $\mathrm{A}_{2}>\mathrm{A}_{1}$ the exposed floor area is $\mathrm{A}_{1}$
6. Repeat for all levels if dwelling has more than two storeys and obtain the total exposed floor area.
4.10 Detailed measurements of roof room
4.11 Heat loss area for houses and bungalows
5. If $\mathrm{A}_{2}>\mathrm{A}_{1}$ the exposed floor area is $\mathrm{A}_{1}$
6. Repeat for all levels if dwelling has more than two storeys and obtain the total exposed floor area.  
When dimensions have been measured internally, the exposed floor area is simply the difference in area between the current floor and the floor below.  
Generally, semi-exposed floors are treated as if they were fully exposed. This is because semi-exposed floors (e.g. floor above garage) are above slightly ventilated spaces making very small reduction to the U value. However, U-value calculated according to BR443 can be used if available.  
The ground floor area of the main dwelling and that of any extension are treated separately as they can have different U-values.
4.12 Heat loss floor area for flats and maisonettes
There is no heat loss through the floor if there is another flat below. Otherwise the floor area of the flat, or the lower floor of the maisonette, is:  
- an exposed floor if there is an open space below;
- a semi-exposed floor if there are unheated premises below it (e.g. an enclosed garage);
- above a partially heated space if there are non-domestic premises below (heated, but at different times);
- a ground floor if there is ground below  
Semi-exposed (sheltered) floors are treated as if they were fully exposed, because semi-exposed are above slightly ventilated spaces making very small reduction to the U-value.
4.12 Heat loss floor area for flats and maisonettes
4.13 Sheltered walls for flats and maisonettes
If the flat or maisonette is adjacent to an unheated corridor or stairwell, the area of wall between the dwelling and the corridor or stairwell is treated as a sheltered (semi-exposed) wall, see 2.4.  
The area of sheltered wall is the shelter length multiplied by the height of the lowest storey, less the door area (see 4.6 and 4.7).  
In any building part there can be an alternative wall which is indicated as sheltered. In this case the assessor does not provide the area of alternative wall; instead, it is calculated from the shelter length as above (this avoids the door to the unheated corridor being deducted twice).  
The length of wall between the dwelling and the unheated corridor or stairwell is included in the exposed perimeter.
4.12 Heat loss floor area for flats and maisonettes
4.13 Sheltered walls for flats and maisonettes
The length of wall between the dwelling and the unheated corridor or stairwell is included in the exposed perimeter.  
When a dwelling (flat or maisonette) has a sheltered wall to an unheated corridor on more than one storey the sheltered length is the total for all storeys with a sheltered wall (example: two storeys with sheltered wall on each storey, length of sheltered wall is 5 m on each storey: enter 10 m for the sheltered length).  
In the case of the wall separating the dwelling from an unheated corridor or stairwell, where this wall is of different construction or insulation to the external walls (e.g. not insulated but external walls are), make it an alternative wall and mark it as sheltered.
5 VENTILATION
5.1 Infiltration (SAP algorithm)
The parameters needed for calculation of the ventilation rate are obtained from Table 5 : Ventilation parameters.  
Table 5 : Ventilation parameters  
| Parameter | Value |
| :--: | :--: |
| Infiltration due to chimneys, flues, fans, passive stack vents, etc. | RdSAP calculation is according to SAP10.2 worksheet: <br> Number of chimneys / flues: <br> - open chimneys <br> - open flues <br> - chimneys / flues attached to closed fire <br> - flues attached to solid fuel boiler <br> - flues attached to other heater <br> Number of blocked chimneys <br> Number of intermittent extract fans <br> Number of passive vents <br> Number of flueless gas fires <br> Infiltration due to chimneys, flues, fans, PSVs, etc. $(6 a) \cdot(6 b) \cdot(6 c) \cdot(6 d) \cdot(6 e) \cdot(6 f) \cdot(7 a) \cdot(7 b) \cdot(7 c)=$ <br> Air changes per hour $(8)$ |
| Chimneys | - Number of open fireplaces for main and for secondary heating, <br> - or " 0 " if not present |
5 VENTILATION
5.1 Infiltration (SAP algorithm)
| Chimneys | - Number of open fireplaces for main and for secondary heating, <br> - or " 0 " if not present |
| Blocked chimneys | - Number of blocked chimneys, or <br> - " 0 " if not present |
| Flues | - Number of open flues (main and secondary heating systems) for main and for secondary heating, or <br> - " 0 " if not present <br> Flue for solid fuel boiler in unheated space is not counted. |
| Chimneys/flues attached to closed fire | - Number for main and for secondary heating, <br> - or " 0 " if not present |
| Flues attached to solid fuel boiler | - Number for main and for secondary heating, <br> - or " 0 " if not present |
| Flues attached to other heater | - Number for main and for secondary heating, <br> - or " 0 " if not present |
| Ventilation system | - Natural with intermittent extract fans, unless mechanical ventilation system clearly identified |  
| Parameter | Value |  |  |
| :--: | :--: | :--: | :--: |
5 VENTILATION
5.1 Infiltration (SAP algorithm)
| Ventilation system | - Natural with intermittent extract fans, unless mechanical ventilation system clearly identified |  
| Parameter | Value |  |  |
| :--: | :--: | :--: | :--: |
| Extract fans | - Number of extract fans if known <br> - If number is unknown: <br> Not park home: <br> Age bands A to E <br> Age bands F to G <br> Age bands H to M <br> Park home: <br> Age band F <br> Age bands G onwards all cases <br> all cases <br> 3 to 5 habitable rooms <br> 6 to 8 habitable rooms <br> more than 8 habitable rooms <br> all cases <br> all cases | 0 1 1 2 3 4 0 2 |  |
| Passive stack vents | - Number of Passive stack vents if known, <br> - or " 0 " if not present |  |  |
| Flueless gas fire | - Number of flueless gas fires if known, <br> - or " 0 " if not present |  |  |
5 VENTILATION
5.1 Infiltration (SAP algorithm)
| Infiltration rate through walls, roofs, floors | Infiltration rate calculated according to SAP10.2 worksheet: <br> If a pressurisation test has been carried out or is intended, proceed to (17), otherwise continue from (9) to (16) <br> Number of storeys in the dwelling $\left(\mathrm{n}_{0}\right)$ <br> Additional infiltration $\quad|(9)-1|=0.1=$ <br> (10) <br> Structural infiltration: 0.25 for steel or timber frame or 0.35 for masonry construction <br> If both types of wall are present, use the value corresponding to the greater wall area (after deducting areas of openings); if equal use 0.35 <br> If suspended wooden ground floor, enter 0.2 (unsealed) or 0.1 (sealed), else enter 0 <br> If no draught lobby, enter 0.05 , else enter 0 <br> Percentage of windows and doors draught proofed <br> Window infiltration $0.25-|0.2=(14)=100|=$ <br> (8) $+(10)+(11)+(12)+(13)+(15)=$ | (12) <br> (13) <br> (14) <br> (15) <br> (16) |
5 VENTILATION
5.1 Infiltration (SAP algorithm)
| Number of storeys | Greater of the number of storeys in the main part of the dwelling and in any extension. |  |
| Walls | Structural infiltration: 0.25 for steel or timber frame or 0.35 for masonry construction; if both present - use prevailing construction; if equal use 0.35 <br> System build: treated as masonry. <br> If both types of walls present, use the value applicable to the greater wall area after deducting areas of openings; if wall areas are equal use 0.35 . <br> Walls of roof rooms: not included. <br> Park home: use value for timber frame. <br> Curtain walls: see section 6.18 below |  |
| Solid and suspended not timber | Solid (structural infiltration 0) <br> Suspended not timber (structural infiltration 0) |  |  
| Parameter | Value |
| :--: | :--: |
5 VENTILATION
5.1 Infiltration (SAP algorithm)
| Solid and suspended not timber | Solid (structural infiltration 0) <br> Suspended not timber (structural infiltration 0) |  |  
| Parameter | Value |
| :--: | :--: |
| Floor infiltration (suspended timber ground floor only) | Default infiltration when : <br> - Age band of main dwelling A to E: <br> a) if floor U-value is $<\mathbf{0 . 5}$, assume "sealed" and use floor infiltration 0.1 <br> b) if floor insulation is 'retro-fitted' and no U-value is supplied, assume "sealed" and use 0.1 ; <br> otherwise "unsealed" and use floor infiltration 0.2 . <br> - Age band of main dwelling $\mathbf{F}$ to $\mathbf{M}$ : sealed <br> (the floor infiltration for the whole dwelling is determined by the floor type of the main dwelling) <br> - Park home: assume unsealed suspended timber and use floor infiltration 0.2 . |
5 VENTILATION
5.1 Infiltration (SAP algorithm)
| Draught lobby | Presence of draught lobby: <br> add infiltration 0.05 if draught lobby is not present, or use 0.0 if present. <br> House, bungalow, or park home: assume no draught lobby if cannot be determined. <br> Flat or maisonette: Assume draught lobby if entrance door is facing corridor (heated or unheated) or stairwell. |
| Infiltration rate applicability | Calculated when pressure test result is not available; however when pressure test result is available it can be used in the calculation. |
5 VENTILATION
5.1 Infiltration (SAP algorithm)
| Pressure test result available | If pressure test result is available (at 50 Pa or 4 Pa ), it is used for calculating effective air change rate. <br> Air permeability value, $\mathrm{AP}_{50},\left(\mathrm{~m}^{3} / \mathrm{h} / \mathrm{m}^{3}\right)$ <br> Air permeability value, $\mathrm{AP}_{\mathrm{A}},\left(\mathrm{m}^{3} / \mathrm{h} / \mathrm{m}^{3}\right)$ <br> If based on air permeability value at 50 Pa , then $(18)=[(17)+20]+(8)$ <br> If based on air permeability value at 4 Pa , then $(18)=[0263 \times(17 a)^{0.504}]+(8)$ <br> If no air permeability test data, then $(18)=(16)$ <br> Air permeability value applies if a pressurisation test has been done, or a design or specified air permeability is being used <br> Number of sides on which dwelling is sheltered <br> Shelter factor <br> (20) $=1-[0.075 \times(19)]=$ <br> (20) <br> Infiltration rate incorporating shelter factor <br> (21) $=(18) \times(20)=$ |
5 VENTILATION
5.1 Infiltration (SAP algorithm)
| Sheltered sides | 0 for detached, <br> 1 for semi-detached or end terraced; <br> 3 for enclosed mid-terraced <br> 2 in other cases (e.g. mid-terraced, including flats) |
| Number of wet rooms (required for an exhaust air heat pump) | 1 to 2 habitable rooms: Kitchen +1 <br> 3 to 4 habitable rooms: Kitchen +2 <br> 5 to 6 habitable rooms: Kitchen +3 <br> 7 to 8 habitable rooms: Kitchen +4 <br> 9 to 10 habitable rooms: Kitchen +5 <br> 11 or more habitable rooms: Kitchen +6 |  
| Parameter | Value |
| :-- | :-- |
| Mechanical ventilation | If details are available, select mechanical ventilation from PCDB, otherwise use default <br> data. <br> Default data given in Table 4 g in SAP10.2 specification: |  
| Type of mechanical ventilation | SFP, <br> W/(litre/sec) | Heat recovery <br> efficiency |
| :-- | :--: | :--: |
| Mechanical extract ventilation (centralised or decentralised), or positive <br> input ventilation from outside | 0.8 | - |
5 VENTILATION
5.1 Infiltration (SAP algorithm)
| :-- | :--: | :--: |
| Mechanical extract ventilation (centralised or decentralised), or positive <br> input ventilation from outside | 0.8 | - |
| Balanced whole house mechanical ventilation, without heat recovery | 2.0 | - |
| Balanced whole house mechanical ventilation, with heat recovery | 2.0 | $66 \%$ |
| Default in-use factors: |  |  |
| For SFP: 2.5 |  |  |
| For efficiency of heat recovery: 0.70 |  |  |  
Age bands mentioned in Table 5 relate to the age of the main dwelling and not to any extension. The number of rooms is as defined in 10.1.
Refer to RdSAP Conventions for the chimney/fireplace definitions and count.
5.2 Provision of ventilation
Ventilation can be provided by one of these methods:  
1) Natural ventilation
2) Positive input - from loft (treated as natural)
3) Positive input - from outside
4) Mechanical extract - centralised
5) Mechanical extract - decentralised
6) Whole House Mechanical Ventilation - no heat recovery
7) Whole House Mechanical Ventilation - with heat recovery  
Items from 2) to 7) in the above list are treated as Mechanical ventilation.
If a mechanical ventilation system present and the details and documentary evidence s are available, use mechanical ventilation from PCDB by specifying brand name and model.
Otherwise use default value for mechanical ventilation in Table 5 : Ventilation parameters.
6 CONSTRUCTION TYPES AND INSULATION (U-VALUES)
Where it can be established that a building element has insulation beyond what would normally be assumed for the age band, this can be specified if adequate evidence exists. Refer to RdSAP Conventions for further details.
6 CONSTRUCTION TYPES AND INSULATION (U-VALUES)
6.1 Wall options
The thickness of stone and brick walls should be measured wherever possible. While the construction elements will often be indicated as 'as-built' or 'unknown insulation,' RdSAP will assign default insulation on the basis of the age band of the part of the property concerned (main dwelling, extension, room in roof).  
Where there is evidence of additional insulation, the assessor has three options:
a. indicate the thickness of insulation, or
b. provide the U-value of the construction element, or
c. select unknown thickness and RdSAP will default.
6 CONSTRUCTION TYPES AND INSULATION (U-VALUES)
6.2 Wall types
RdSAP allows the following wall types:  
- Stone (granite or whinstone)
- Stone (sandstone or limestone)
- Solid brick
- Cob
- Cavity (unfilled, filled)
- System built.  
If the dwelling has a wall type that does not correspond closely with one of the available options, select the nearest equivalent taking account of the U -values in the tables below and include Addendum 1 (see section 14 : Addendum to EPCs).
6 CONSTRUCTION TYPES AND INSULATION (U-VALUES)
6.2.1 Cavity wall
Where a cavity wall has been identified, it is recorded irrespective of the width of the cavity. However, insulation level, presence of dry-lining and wall thickness should be recorded.
6 CONSTRUCTION TYPES AND INSULATION (U-VALUES)
6.2.2 System Built wall
System built wall is a wall other than masonry or timber-framed.
See RdSAP conventions in relation to system-built dwellings greater than four storeys.
6 CONSTRUCTION TYPES AND INSULATION (U-VALUES)
6.2.3 Unknown wall type
Do not use the 'unknown' option for wall insulation inappropriately as this automatically suppresses any insulation recommendation; assume as-built if no evidence of retro-fitted insulation.
'Unknown' should be used only in exceptional circumstances, e.g. when there is conflicting evidence (inspection and/or documentary) of added insulation whose presence cannot be ascertained conclusively. In these cases clarification must be provided in site notes.  
Note that "Unknown" wall type will automatically suppress any insulation recommendation.
Refer to RdSAP Conventions.
6 CONSTRUCTION TYPES AND INSULATION (U-VALUES)
6.2.4 Wall adjacent to stairwell or corridor
Stairwells and access corridors are not regarded as parts of the dwelling, however wall adjacent to stairwell or access corridor can be treated as sheltered alternative wall (if stairwell or corridor is unheated), or as party wall (if heated).
Refer to RdSAP conventions for definition of heated corridor.
6.2.5 Dwelling adjacent to non-domestic (commercial) premises
If a dwelling or part of a dwelling has commercial premises below record as partially heated space below. If a dwelling or part of a dwelling has commercial premises above record as another dwelling above. If a dwelling has commercial premises alongside it, treat as a party wall.  
Refer to RdSAP conventions for more details.
6.2.5 Dwelling adjacent to non-domestic (commercial) premises
6.2.6 Curtain wall
The definition of a curtain wall is given in section 2.5; see also section 6.18 below for the details of curtain wall.
6.2.5 Dwelling adjacent to non-domestic (commercial) premises
6.3 U-value for walls, roofs, floors
U-values of construction elements are determined within software from the constructional type, date of construction and, where applicable, thickness of additional insulation, according to the tables below.  
U values are obtained separately for the main part of the dwelling and for any extension. If the insulation status is unknown, the relevant value for 'as built' is used.  
A U-value is that of the whole element, including any added insulation.  
The U-values of existing elements (walls/roofs/floors, etc.) must be the RdSAP default values (e.g. entered "as built") and must not be overwritten unless specific documentary evidence of the thermal conductivity of individual materials of the building element of the property being assessed is provided and was undertaken in accordance with BR 443 "Conventions for U-value calculations" (BRE, 2019).
6.2.5 Dwelling adjacent to non-domestic (commercial) premises
6.3 U-value for walls, roofs, floors
Documentary evidence applicable to the property being assessed must be provided and recorded if overwriting any default U-value. See RdSAP10 Conventions for the details of documentary evidence.  
Otherwise Table 31 : Data to be collected indicates the options required for collection of data on site in respect of additional insulation of elements.  
These are:  
- floor insulation
- cavity filled wall
- internal and/or external wall insulation
- party wall insulation (cavity fill)
- measured thickness of loft insulation
- rafter insulation
- flat roof insulation
- insulation of roof rooms  
A U-value is assigned to an insulated loft according to the measured insulation thickness. In other cases the U-value with additional insulation is based on the thickness of insulation of mineral wool type (assume 100 mm if thickness is unknown).  
If insulation is multifoil or foam insulation refer to RdSAP Conventions.
6.2.5 Dwelling adjacent to non-domestic (commercial) premises
6.3 U-value for walls, roofs, floors
If insulation is multifoil or foam insulation refer to RdSAP Conventions.
If there is both internal and external wall insulation add the insulation thicknesses together and enter as external.
6.2.5 Dwelling adjacent to non-domestic (commercial) premises
6.4 Default U-values of external walls
Unless the U-value is available (subject to documentary evidence) use the default wall U-values given in: Table 6 : Wall U-values - England
Table 7 : Wall U-values - Scotland
Table 8 : Wall U-values - Northern Ireland
Table 9 : Wall U-values - Wales
Table 10 : Wall U-values - Isle of Man  
Table 6 : Wall U-values - England  
|  Age band | A | B | C | D | E | F | G | H | I | J | K | L | M  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
|  Wall type |  |  |  |  |  |  |  |  |  |  |  |  |   |
|  Stone: granite or whinstone | According to 6.6 |  |  |  | 1.7 a | 1.0 | 0.60 | 0.60 | 0.45 | 0.35 | 0.30 | 0.28 | 0.26  |
|  Stone: sandstone or limestone |  |  |  |  | 1.7 a | 1.0 | 0.60 | 0.60 | 0.45 | 0.35 | 0.30 | 0.28 | 0.26  |
|  Solid brick as built | According to 6.7 |  |  |  | 1.7b | 1.0 | 0.60 | 0.60 | 0.45 | 0.35 | 0.30 | 0.28 | 0.26  |
6.2.5 Dwelling adjacent to non-domestic (commercial) premises
6.4 Default U-values of external walls
|  Solid brick as built | According to 6.7 |  |  |  | 1.7b | 1.0 | 0.60 | 0.60 | 0.45 | 0.35 | 0.30 | 0.28 | 0.26  |
|  Stone/solid brick with 50 mm external or internal insulation | According to 6.8 |  |  |  | 0.55 c | $0.45^{*}$ | $0.35^{*}$ | $0.35^{*}$ | $0.30^{*}$ | $0.25^{*}$ | $0.21^{*}$ | $0.21^{*}$ | $0.20^{*}$  |
|  Stone/solid brick with 100 mm external or internal insulation |  |  |  |  | 0.32 c | $0.28^{*}$ | $0.24^{*}$ | $0.24^{*}$ | $0.21^{*}$ | $0.19^{*}$ | $0.17^{*}$ | $0.16^{*}$ | $0.15^{*}$  |
|  Stone/solid brick with 150 mm external or internal insulation |  |  |  |  | 0.23 c | $0.21^{*}$ | $0.18^{*}$ | $0.18^{*}$ | $0.17^{*}$ | $0.15^{*}$ | $0.14^{*}$ | $0.14^{*}$ | $0.13^{*}$  |
|  Stone/solid brick with 200 mm external or internal insulation |  |  |  |  | 0.18 c | $0.17^{*}$ | $0.15^{*}$ | $0.15^{*}$ | $0.14^{*}$ | $0.13^{*}$ | $0.12^{*}$ | $0.12^{*}$ | $0.11^{*}$  |
6.2.5 Dwelling adjacent to non-domestic (commercial) premises
6.4 Default U-values of external walls
|  Stone/solid brick with 200 mm external or internal insulation |  |  |  |  | 0.18 c | $0.17^{*}$ | $0.15^{*}$ | $0.15^{*}$ | $0.14^{*}$ | $0.13^{*}$ | $0.12^{*}$ | $0.12^{*}$ | $0.11^{*}$  |
|  Cob (as built) | 0.80 | 0.80 | 0.80 | 0.80 | 0.80 | 0.80 | 0.60 | 0.60 | 0.45 | 0.35 | 0.30 | 0.28 | 0.26  |
|  Cob with 50 mm external or internal insulation | 0.40 | 0.40 | 0.40 | 0.40 | 0.40 | 0.40 | $0.35^{*}$ | $0.35^{*}$ | $0.30^{*}$ | $0.25^{*}$ | $0.21^{*}$ | $0.21^{*}$ | $0.20^{*}$  |
|  Cob with 100 mm external or internal insulation | 0.26 | 0.26 | 0.26 | 0.26 | 0.26 | 0.26 | $0.24^{*}$ | $0.24^{*}$ | $0.21^{*}$ | $0.19^{*}$ | $0.17^{*}$ | $0.16^{*}$ | $0.15^{*}$  |
|  Cob with 150 mm external or internal insulation | 0.20 | 0.20 | 0.20 | 0.20 | 0.20 | 0.20 | $0.18^{*}$ | $0.18^{*}$ | $0.17^{*}$ | $0.15^{*}$ | $0.14^{*}$ | $0.14^{*}$ | $0.13^{*}$  |
6.2.5 Dwelling adjacent to non-domestic (commercial) premises
6.4 Default U-values of external walls
|  Cob with 150 mm external or internal insulation | 0.20 | 0.20 | 0.20 | 0.20 | 0.20 | 0.20 | $0.18^{*}$ | $0.18^{*}$ | $0.17^{*}$ | $0.15^{*}$ | $0.14^{*}$ | $0.14^{*}$ | $0.13^{*}$  |
|  Cob with 200 mm external or internal insulation | 0.16 | 0.16 | 0.16 | 0.16 | 0.16 | 0.16 | $0.15^{*}$ | $0.15^{*}$ | $0.14^{*}$ | $0.13^{*}$ | $0.12^{*}$ | $0.12^{*}$ | $0.11^{*}$  |
|  Cavity as built | 1.5 | 1.5 | 1.5 | 1.5 | 1.5 | 1.0 | 0.60 | 0.60 | 0.45 | 0.35 | 0.30 | 0.28 | 0.26  |
|  Unfilled cavity with 50 mm external or internal insulation | 0.53 | 0.53 | 0.53 | 0.53 | 0.53 | 0.45 | $0.35^{*}$ | $0.35^{*}$ | $0.30^{*}$ | $0.25^{*}$ | $0.21^{*}$ | $0.21^{*}$ | $0.20^{*}$  |
|  Unfilled cavity with 100 mm external or internal insulation | 0.32 | 0.32 | 0.32 | 0.32 | 0.32 | 0.30 | $0.24^{*}$ | $0.24^{*}$ | $0.21^{*}$ | $0.19^{*}$ | $0.17^{*}$ | $0.16^{*}$ | $0.15^{*}$  |
6.2.5 Dwelling adjacent to non-domestic (commercial) premises
6.4 Default U-values of external walls
|  Unfilled cavity with 100 mm external or internal insulation | 0.32 | 0.32 | 0.32 | 0.32 | 0.32 | 0.30 | $0.24^{*}$ | $0.24^{*}$ | $0.21^{*}$ | $0.19^{*}$ | $0.17^{*}$ | $0.16^{*}$ | $0.15^{*}$  |
|  Unfilled cavity with 150 mm external or internal insulation | 0.23 | 0.23 | 0.23 | 0.23 | 0.23 | 0.21 | $0.18^{*}$ | $0.18^{*}$ | $0.17^{*}$ | $0.15^{*}$ | $0.14^{*}$ | $0.14^{*}$ | $0.13^{*}$  |
|  Unfilled cavity with 200 mm external or internal insulation | 0.18 | 0.18 | 0.18 | 0.18 | 0.18 | $0.17^{*}$ | $0.15^{*}$ | $0.15^{*}$ | $0.14^{*}$ | $0.13^{*}$ | $0.12^{*}$ | $0.12^{*}$ | $0.11^{*}$  |
|  Filled cavity | 0.7 | 0.7 | 0.7 | 0.7 | 0.7 | 0.40 | 0.35 | 0.35 | $0.45^{1}$ | $0.35^{1}$ | $0.30^{1}$ | $0.28^{1}$ | $0.26^{1}$  |
|  Filled cavity with 50 mm external or internal insulation | 0.37 | 0.37 | 0.37 | 0.37 | 0.37 | 0.27 | $0.25^{*}$ | $0.25^{*}$ | $0.25^{*}$ | $0.25^{*}$ | $0.21^{*}$ | $0.21^{*}$ | $0.20^{*}$  |
6.2.5 Dwelling adjacent to non-domestic (commercial) premises
6.4 Default U-values of external walls
|  Filled cavity with 50 mm external or internal insulation | 0.37 | 0.37 | 0.37 | 0.37 | 0.37 | 0.27 | $0.25^{*}$ | $0.25^{*}$ | $0.25^{*}$ | $0.25^{*}$ | $0.21^{*}$ | $0.21^{*}$ | $0.20^{*}$  |
|  Filled cavity with 100 mm external or internal insulation | 0.25 | 0.25 | 0.25 | 0.25 | 0.25 | 0.20 | $0.19^{*}$ | $0.19^{*}$ | $0.19^{*}$ | $0.19^{*}$ | $0.17^{*}$ | $0.16^{*}$ | $0.15^{*}$  |
|  Filled cavity with 150 mm external or internal insulation | 0.19 | 0.19 | 0.19 | 0.19 | 0.19 | 0.16 | $0.15^{*}$ | $0.15^{*}$ | $0.15^{*}$ | $0.15^{*}$ | $0.14^{*}$ | $0.14^{*}$ | $0.13^{*}$  |
|  Filled cavity with 200 mm external or internal insulation | 0.16 | 0.16 | 0.16 | 0.16 | 0.16 | 0.13 | $0.13^{*}$ | $0.13^{*}$ | $0.13^{*}$ | $0.13^{*}$ | $0.12^{*}$ | $0.12^{*}$ | $0.11^{*}$  |
|  Timber frame as built | 2.5 | 1.9 | 1.9 | 1.0 | 0.80 | 0.45 | 0.40 | 0.40 | 0.40 | 0.35 | 0.30 | 0.28 | 0.26  |
6.2.5 Dwelling adjacent to non-domestic (commercial) premises
6.4 Default U-values of external walls
|  Timber frame as built | 2.5 | 1.9 | 1.9 | 1.0 | 0.80 | 0.45 | 0.40 | 0.40 | 0.40 | 0.35 | 0.30 | 0.28 | 0.26  |
|  Timber frame with internal insulation | 0.60 | 0.55 | 0.55 | 0.40 | 0.40 | 0.40 | $0.40^{1}$ | $0.40^{1}$ | $0.40^{1}$ | $0.35^{1}$ | $0.30^{1}$ | $0.28^{1}$ | $0.26^{1}$  |
|  System build as built | 2.0 | 2.0 | 2.0 | 2.0 | 1.7 | 1.0 | 0.60 | 0.60 | 0.45 | 0.35 | 0.30 | 0.28 | 0.26  |
|  System build with 50 mm external or internal insulation | 0.60 | 0.60 | 0.60 | 0.60 | 0.55 | 0.45 | $0.35^{*}$ | $0.35^{*}$ | $0.30^{*}$ | $0.25^{*}$ | $0.21^{*}$ | $0.21^{*}$ | $0.20^{*}$  |
|  System build with 100 mm external or internal insulation | 0.35 | 0.35 | 0.35 | 0.35 | 0.35 | $0.32^{*}$ | $0.24^{*}$ | $0.24^{*}$ | $0.21^{*}$ | $0.19^{*}$ | $0.17^{*}$ | $0.16^{*}$ | $0.15^{*}$  |
6.2.5 Dwelling adjacent to non-domestic (commercial) premises
6.4 Default U-values of external walls
|  System build with 150 mm external or internal insulation | 0.25 | 0.25 | 0.25 | 0.25 | 0.25 | $0.21^{*}$ | $0.18^{*}$ | $0.18^{*}$ | $0.17^{*}$ | $0.15^{*}$ | $0.14^{*}$ | $0.14^{*}$ | $0.13^{*}$  |
|  System build with 200 mm external or internal insulation | 0.18 | 0.18 | 0.18 | 0.18 | 0.18 | $0.17^{*}$ | $0.15^{*}$ | $0.15^{*}$ | $0.14^{*}$ | $0.13^{*}$ | $0.12^{*}$ | $0.12^{*}$ | $0.11^{*}$  |  
a Or from equations in 6.6 if the calculated $U$-value is less than 1.7 . b Or from 6.7 if wall thickness is other than 200 mm to 280 mm c According to 6.8  
- wall may have had internal or external insulation when originally built; this applies only if insulation is known to have been increased subsequently (otherwise 'as built' applies) ${ }^{1}$ assumed as built If a wall is known to have additional insulation but the insulation thickness is unknown, use the row in the table for 50 mm insulation  
Table 7 : Wall U-values - Scotland
6.2.5 Dwelling adjacent to non-domestic (commercial) premises
6.4 Default U-values of external walls
Table 7 : Wall U-values - Scotland  
|  Age band | A | B | C | D | E | F | G | H | I | J | K | L | M  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
|  Wall type |  |  |  |  |  |  |  |  |  |  |  |  |   |
|  Stone: granite or whinstone as built | According to 6.6 |  |  |  | 1.7 a | 1.0 | 0.60 | 0.45 | 0.45 | 0.30 | 0.25 | 0.22 | 0.17  |
|  Stone: sandstone or limestone as built |  |  |  |  | 1.5 a | 1.0 | 0.60 | 0.45 | 0.45 | 0.30 | 0.25 | 0.22 | 0.17  |
|  Solid brick as built | According to 6.7 |  |  |  | 1.7b | 1.0 | 0.60 | 0.45 | 0.45 | 0.30 | 0.25 | 0.22 | 0.17  |
|  Stone/solid brick with 50 mm external or internal insulation | According to 6.8 |  |  |  | 0.55 c | $0.45^{*}$ | $0.35^{*}$ | $0.30^{*}$ | $0.30^{*}$ | $0.21^{*}$ | $0.19^{*}$ | $0.17^{*}$ | $0.14^{*}$  |
6.2.5 Dwelling adjacent to non-domestic (commercial) premises
6.4 Default U-values of external walls
|  Stone/solid brick with 100 mm external or internal insulation |  |  |  |  | 0.32 c | $0.28^{*}$ | $0.24^{*}$ | $0.24^{*}$ | $0.21^{*}$ | $0.19^{*}$ | $0.17^{*}$ | $0.14^{*}$ | $0.12^{*}$  |
|  Stone/solid brick with 150 mm external or internal insulation |  |  |  |  | 0.23 c | $0.21^{*}$ | $0.18^{*}$ | $0.18^{*}$ | $0.17^{*}$ | $0.15^{*}$ | $0.14^{*}$ | $0.12^{*}$ | $0.10^{*}$  |
|  Stone/solid brick with 200 mm external or internal insulation |  |  |  |  | 0.18 c | $0.17^{*}$ | $0.15^{*}$ | $0.15^{*}$ | $0.14^{*}$ | $0.13^{*}$ | $0.12^{*}$ | $0.10^{*}$ | $0.09^{*}$  |
|  Cob as built | 0.80 | 0.80 | 0.80 | 0.80 | 0.80 | 0.80 | 0.60 | 0.60 | 0.45 | 0.30 | 0.25 | 0.22 | 0.17  |
|  Cob with 50 mm external or internal insulation | 0.40 | 0.40 | 0.40 | 0.40 | 0.40 | 0.40 | $0.35^{*}$ | $0.35^{*}$ | $0.30^{*}$ | $0.21^{*}$ | $0.19^{*}$ | $0.17^{*}$ | $0.14^{*}$  |
6.2.5 Dwelling adjacent to non-domestic (commercial) premises
6.4 Default U-values of external walls
|  Cob with 50 mm external or internal insulation | 0.40 | 0.40 | 0.40 | 0.40 | 0.40 | 0.40 | $0.35^{*}$ | $0.35^{*}$ | $0.30^{*}$ | $0.21^{*}$ | $0.19^{*}$ | $0.17^{*}$ | $0.14^{*}$  |
|  Cob with 100 mm external or internal insulation | 0.26 | 0.26 | 0.26 | 0.26 | 0.26 | 0.26 | $0.24^{*}$ | $0.24^{*}$ | $0.21^{*}$ | $0.19^{*}$ | $0.17^{*}$ | $0.14^{*}$ | $0.12^{*}$  |
|  Cob with 150 mm external or internal insulation | 0.20 | 0.20 | 0.20 | 0.20 | 0.20 | 0.20 | $0.18^{*}$ | $0.18^{*}$ | $0.17^{*}$ | $0.15^{*}$ | $0.14^{*}$ | $0.12^{*}$ | $0.10^{*}$  |
|  Cob with 200 mm external or internal insulation | 0.16 | 0.16 | 0.16 | 0.16 | 0.16 | 0.16 | $0.15^{*}$ | $0.15^{*}$ | $0.14^{*}$ | $0.13^{*}$ | $0.12^{*}$ | $0.10^{*}$ | $0.09^{*}$  |
|  Cavity as built | 1.5 | 1.5 | 1.5 | 1.5 | 1.5 | 1.0 | 0.60 | 0.45 | 0.45 | 0.30 | 0.25 | 0.22 | 0.17  |
6.2.5 Dwelling adjacent to non-domestic (commercial) premises
6.4 Default U-values of external walls
|  Cavity as built | 1.5 | 1.5 | 1.5 | 1.5 | 1.5 | 1.0 | 0.60 | 0.45 | 0.45 | 0.30 | 0.25 | 0.22 | 0.17  |
|  Unfilled cavity with 50 mm external or internal insulation | 0.53 | 0.53 | 0.53 | 0.53 | 0.53 | 0.45 | $0.35^{*}$ | $0.30^{*}$ | $0.30^{*}$ | $0.25^{*}$ | $0.19^{*}$ | $0.17^{*}$ | $0.14^{*}$  |
|  Unfilled cavity with 100 mm external or internal insulation | 0.32 | 0.32 | 0.32 | 0.32 | 0.32 | 0.30 | $0.24^{*}$ | $0.21^{*}$ | $0.21^{*}$ | $0.19^{*}$ | $0.17^{*}$ | $0.14^{*}$ | $0.12^{*}$  |
|  Unfilled cavity with 150 mm external or internal insulation | 0.23 | 0.23 | 0.23 | 0.23 | 0.23 | 0.21 | $0.18^{*}$ | $0.17^{*}$ | $0.17^{*}$ | $0.15^{*}$ | $0.14^{*}$ | $0.12^{*}$ | $0.10^{*}$  |
|  Unfilled cavity with 200 mm external or internal insulation | 0.18 | 0.18 | 0.18 | 0.18 | 0.18 | $0.17^{*}$ | $0.15^{*}$ | $0.15^{*}$ | $0.14^{*}$ | $0.13^{*}$ | $0.12^{*}$ | $0.10^{*}$ | $0.09^{*}$  |
6.2.5 Dwelling adjacent to non-domestic (commercial) premises
6.4 Default U-values of external walls
|  Filled cavity | 0.7 | 0.7 | 0.7 | 0.7 | 0.7 | 0.40 | 0.35 | $0.45^{\dagger}$ | $0.45^{\dagger}$ | $0.30^{\dagger}$ | $0.25^{\dagger}$ | $0.22^{\dagger}$ | 0.17  |
|  Filled cavity with 50 mm external or internal insulation | 0.37 | 0.37 | 0.37 | 0.37 | 0.37 | 0.27 | $0.25^{*}$ | $0.25^{*}$ | $0.25^{*}$ | $0.25^{*}$ | $0.25^{*}$ | $0.17^{*}$ | $0.14^{*}$  |
|  Filled cavity with 100 mm external or internal insulation | 0.25 | 0.25 | 0.25 | 0.25 | 0.25 | 0.20 | $0.19^{*}$ | $0.19^{*}$ | $0.19^{*}$ | $0.19^{*}$ | $0.19^{*}$ | $0.14^{*}$ | $0.12^{*}$  |
|  Filled cavity with 150 mm external or internal insulation | 0.19 | 0.19 | 0.19 | 0.19 | 0.19 | 0.16 | $0.15^{*}$ | $0.15^{*}$ | $0.15^{*}$ | $0.15^{*}$ | $0.15^{*}$ | $0.12^{*}$ | $0.10^{*}$  |
|  Filled cavity with 200 mm external or internal insulation | 0.16 | 0.16 | 0.16 | 0.16 | 0.16 | 0.13 | $0.13^{*}$ | $0.13^{*}$ | $0.13^{*}$ | $0.13^{*}$ | $0.12^{*}$ | $0.10^{*}$ | $0.09^{*}$  |
6.2.5 Dwelling adjacent to non-domestic (commercial) premises
6.4 Default U-values of external walls
|  Filled cavity with 200 mm external or internal insulation | 0.16 | 0.16 | 0.16 | 0.16 | 0.16 | 0.13 | $0.13^{*}$ | $0.13^{*}$ | $0.13^{*}$ | $0.13^{*}$ | $0.12^{*}$ | $0.10^{*}$ | $0.09^{*}$  |
|  Timber frame as built | 2.5 | 1.9 | 1.9 | 1.0 | 0.80 | 0.45 | 0.40 | 0.40 | 0.40 | 0.30 | 0.25 | 0.22 | 0.17  |
|  Timber frame with internal insulation | 0.60 | 0.55 | 0.55 | 0.40 | 0.40 | 0.40 | $0.40^{\dagger}$ | $0.40^{\dagger}$ | $0.40^{\dagger}$ | $0.30^{\dagger}$ | $0.25^{\dagger}$ | $0.22^{\dagger}$ | $0.17^{\dagger}$  |
|  System build as built | 2.0 | 2.0 | 2.0 | 2.0 | 1.7 | 1.0 | 0.60 | 0.45 | 0.45 | 0.30 | 0.25 | 0.22 | 0.17  |
|  System build with 50 mm external or internal insulation | 0.60 | 0.60 | 0.60 | 0.60 | 0.55 | 0.45 | $0.35^{*}$ | $0.30^{*}$ | $0.30^{*}$ | $0.21^{*}$ | $0.19^{*}$ | $0.17^{*}$ | $0.14^{*}$  |
6.2.5 Dwelling adjacent to non-domestic (commercial) premises
6.4 Default U-values of external walls
|  System build with 50 mm external or internal insulation | 0.60 | 0.60 | 0.60 | 0.60 | 0.55 | 0.45 | $0.35^{*}$ | $0.30^{*}$ | $0.30^{*}$ | $0.21^{*}$ | $0.19^{*}$ | $0.17^{*}$ | $0.14^{*}$  |
|  System build with 100 mm external or internal insulation | 0.35 | 0.35 | 0.35 | 0.35 | 0.35 | $0.32^{*}$ | $0.24^{*}$ | $0.24^{*}$ | $0.21^{*}$ | $0.19^{*}$ | $0.17^{*}$ | $0.14^{*}$ | $0.12^{*}$  |
|  System build with 150 mm external or internal insulation | 0.25 | 0.25 | 0.25 | 0.25 | 0.25 | $0.21^{*}$ | $0.18^{*}$ | $0.18^{*}$ | $0.17^{*}$ | $0.15^{*}$ | $0.14^{*}$ | $0.12^{*}$ | $0.10^{*}$  |
|  System build with 200 mm external or internal insulation | 0.18 | 0.18 | 0.18 | 0.18 | 0.18 | $0.17^{*}$ | $0.15^{*}$ | $0.15^{*}$ | $0.14^{*}$ | $0.13^{*}$ | $0.12^{*}$ | $0.10^{*}$ | $0.09^{*}$  |  
a Or from equations in 6.6 if the calculated U-value is less than 1.7 . b Or from 6.7 if wall thickness is other than 200 mm to 280 mm c According to 6.8
6.2.5 Dwelling adjacent to non-domestic (commercial) premises
6.4 Default U-values of external walls
a Or from equations in 6.6 if the calculated U-value is less than 1.7 . b Or from 6.7 if wall thickness is other than 200 mm to 280 mm c According to 6.8  
- wall may have had internal or external insulation when originally built; this applies only if insulation is known to have been increased subsequently (otherwise 'as built' applies) ${ }^{\dagger}$ assumed as built If a wall is known to have additional insulation but the insulation thickness is unknown, use the row in the table for 50 mm insulation  
Table 8 : Wall U-values - Northern Ireland  
|  Age band | A | B | C | D | E | F | G | H | I | J | K | L | M  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
|  Wall type |  |  |  |  |  |  |  |  |  |  |  |  |   |
|  Stone: granite or whinstone as built | According to 6.6 |  |  |  | 1.7 b | 1.0 | 0.60 | 0.45 | 0.45 | - | 0.30 | 0.28 | 0.18  |