Briary Energy Conventions
25th July 2017

SAP 2012 v7.0 Conventions – Briary Summary

Summary (in effect from 31 August 2017 v 7.0)

For any and all Scottish SAPs refer to further differences on the 38 page document. In short, most Scottish regulations are more onerous.

1.04 Thermal Bridges must now be signed off before producing an EPC.
2.01 Confirmed dimensions for garage within dwellings, see Apendix 4.
Appendix 4. Dwelling dimensions (the diagrams below show how to measure height of storeys in order to calculate volume of dwelling)

Multi-storey dwellings
Dwelling without a garage & Dwelling with a garage

Blocks of flats
Block of flats without a garage & Block of flats with a garage

The difference in the approach to floor heights is due to the method of calculating thermal bridging of junctions. For blocks of flats the space between floors is already included in the psi-values, while the space between floors in other dwellings is not included, therefore the area of wall should be added.
2.03 Voids are no longer included in the volume calculation, but the full internal height of the external wall should be included as normal.

2.07 Where the roof insulation follows the shape of the room, the U-value of the walls and ceilings to the unheated roof voids should be calculated as normal with the room–in-roof shelter factor applied.
Where the insulation is contained entirely within the rafters, the U-value of the sloping ceilings should be multiplied by a factor of 0.72, and the resultant U-value used for the walls and ceilings to the unheated voids spaces. The new stud like elements are called Ashlar walls or Ashlar roof/ceilings.

4.03 Solar powered vents should be entered into SAP software as passive vents.
4.06 Disregard a single individual ventilator with heat recovery, if individual intermittent ventilators with heat recovery installed in each wet room, treat as natural ventilation with intermittent extract fans; if continuously running – treat as default Decentralized Extract Ventilation; in this case the heat recovery element is disregarded.
4.07 Positive input ventilators – In the case of PIV supplying preheated air from the loft – specify the actual number of extract fans, with a minimum of 2 extract fans required.
5.02 Swimming pools, U-value as the surrounding floor, ignoring the basin, but the u-value of the basin walls should be provided to building control separately.
5.04 g-values for BFRC windows are usually less than 0.5 and should be checked if greater. In the case of manufacturer-declared properties of windows the data needed as U-value, g-value for the glazing and frame factor. Documentary evidence of these data is required.
For windows and roof windows that are NOT vertical BR 443 gives U-value adjustment which can be applied to windows and roof windows depending on the inclination.

5.07 If a T-value for any junction is not available use the applicable default value from SAP Table K1 (see 5.08 for exceptions). The following junctions in Table K1 have no ACDs associated with them and so no ACD reference number: E8, E9, E16, E17, E19, E20, E21, E22, E23, E24, E25, P1, P6, P7, P8, R1 to R9. If no calculated value is available use the default T-value.

5.15 Thermal mass parameters can be calculated (but as per BR 443 do not include internal doors), or treated as being low, medium or high using the global values of 100, 250 or 450 kJ/m²K given in SAP 2012 Table 1f .
5.16 An oriel window is a form of bay window, which projects from the main wall of a building but does not reach to the ground.

Method 1: Oriel window modelled by detailed analysis

Ueffective takes into the account heat losses associated with thermal bridging so Ψ-values associated with sills, jams and lintels are zero.

6.13 In the case of community heating treat electric underfloor heating of small rooms (i.e. wet rooms) as a secondary room heater (panel, convector or radiant heater).
7.05 Instantaneous electric showers are included in the total number of showers in the dwelling but should NOT be included in the number of showers served by the WWHRS, because electric showers cannot have a WWHRS. For as-built assessments documentary evidence in the form of a completed WWHRS checklist is required.

Method 2: Oriel window not modelled

You can download a copy of version 7.0 of the SAP Conventions here.
To discuss your project requirements, please contact us.

Read More