Potential issues leading to non-compliance with SAP assessment criteria
The following design and as built stage issues are those that most commonly lead to non-compliance with SAP assessment criteria. It’s important to be aware of these issues before you begin the process of assessment.
DESIGN STAGE
+ Poor drawings and lack of information or specification.
+ The ventilation strategy is not defined.
+ “Minimum” U-values specified, without proof.
+ Heating details are not specified meaning assumptions need to be made, potentially making the result poorer than if correctly specified heating and controls are used.
+ Realistic air leakage figures are not assumed. These should be set according to the ventilation strategy, Building Regulations and past experience of air pressure test results achieved.
+ SAP conventions not adhered to, meaning incorrect DER calculation is produced.
AS BUILT STAGE
+ Poor drawings and lack of information or specification.
+ The ventilation strategy is not defined.
+ “Minimum” U-values specified, without proof.
+ Heating system and controls not installed as per the Design Stage calculation inputs.
+ Specified junction details not built to meaning PSI-value inputs need to be adjusted.
+ The air pressure test result is higher than assumed in the Design Stage calculation.
+ Changes made to the dwelling design and/or product substitution (if not communicated to assessor during build.
+ Window specifications do not match design, in terms of U-value, frame factor and g-value; or BFRC figures specified, but different windows installed.
+ Secondary heating installed when not in original design.
+ SAP conventions not adhered to, meaning incorrect DER calculation is produced, and EPC audit failure.