Laboratory Proficiency Scheme PAS 100 and PAS 110 Certification

PAS100:2011 and PAS110:2010 are a crucial component of market confidence in compost and digestate quality, consistency and safety. Integral to this is confidence in the quality of the laboratory data being used to assess material quality.

This project looked at developing a framework for a laboratory proficiency scheme that could be implemented by the UK certification schemes to ensure that laboratory performance is consistent and adequate across the range of tests required for the materials.

Renewable Energy Assurance Ltd (REAL) operates the Certification Schemes which accredit materials to PAS 100 and PAS 110 specifications.

A review of the use of test methods and quality control procedures used by the current laboratories was carried out and the relevance of existing proficiency testing schemes (PTS) in providing additional control on data quality was assessed.


  • Internal laboratory quality assurance and control measures should always provide the first port of call in controlling data quality, while proficiency testing schemes should be used to supplement these. Scheme participation is no guarantee of consistency or accuracy unless poor performance is monitored and acted upon. 
  • The small number of current appointed laboratories would severely limit the value of a UK PAS-specific PTS(s). Setting up a new scheme would be expensive and potentially not financially viable for the size of the current PAS testing business. In addition there would be large uncertainties in test result interpretation and performance evaluation.
  • Rather than immediately deploy a PTS for UK compost and digestate testing laboratories, a number of steps are proposed to better ensure the reliability and accuracy of data. Please see the report for more information.