Retrofit insulation standards are established as follows:

• Specific requirements under Scottish Government initiatives such as Warmer Homes Scotland and the Home Energy Scotland grants and loans require installers to be registered with TrustMark for the relevant trade.
• Product CE Marking/hEN’s and ETAs and associated manufacturers guidance.
• Requirements under independent certification schemes, such as system specific Agrément Certificates, may specify the scope of use and set out installation and training requirements.