SAP Conventions Update

Focus have reviewed the changes, and the key elements are summarised below:

U-Value Calculations – BR443

These are calculated using the conventions given in BR 443.  The conventions regarding who can provide these calculations have been amended.  The acceptable routes are:

• Calculation provided by a person that is a member of a recognised U-value calculation competency scheme, or,
• Calculation provided by an OCDEA, level 4 NDEA or any other process recognised by Accreditation Schemes/Approved Organisation and Government, or,
• Calculation provided by another party and checked by the Assessor.

It is expected that if you obtain a calculation on request from a product manufacturer they will be in compliance with the above. Focus have multiple staff members who comply with the above, and can assist with either creating or reviewing U-Value calculations.

Windows

There is a general drive throughout the conventions update towards actual product data rather than the use of default figures.  This is most apparent in the windows section, where actual manufacturers product data will be expected at ‘As Built’ Stage.  The data required will be:

1. U-Value ( W/m²K )
2. G-Value (% of transmittance)
3. Frame Factor (% Frame to Glass ) 

The alternative and better approach is to use BFRC ( British Fenestration Rating Council ) or other approved certification bodies product information.

In this case the U-value and G-value are taken from the front of the certificate or from the simulation report produced by the BFRC certified simulator. 

This information will be required by the SAP assessor at ‘As Built’ stage at the latest, and it is suggested that the relevant information is passed to the assessor as soon as possible, to ensure that any issues with SAP performance can be mitigated as early as possible.

Party Wall U-Values

If zero heat loss is to be achieved in SAP calculations through the use of a filled and sealed cavity, either confirmation that MIMA Guidance has been adhered to, or written confirmation from builder that filling, and sealing has been done.  It is expected that confirmation as part of a general ‘As Built’ specification confirmation would be sufficient.

Thermal Bridging

While this is not a specific update in SAP Conventions 8.2, it is clear that the Government sees this as a key element in regard to the ‘Performance Gap’ and the intention is to require more robust evidence and checking for Thermal Bridging.  It is expected that the SAP assessor and client will agree the thermal bridges (and associated psi values) to be used at Design Stage, we recommend informing the design team what has been assumed/proposed as soon possible so any updates/amendments can be made if required. 

At ‘As Built’ Stage the client will be required to specifically review the thermal bridge details used and confirm that these are representative of the As Built construction. 

Ideally this confirmation would take the form of signed checklists, but it is accepted that this will not always be possible where bespoke calculations are to be used.  This increased checking is seen as a step towards the changes under the proposed 2022 Part L1A update, where use in SAP of Accredited Construction Details will no longer be acceptable, and photographic evidence from site of As Built junctions will be required.