We recognise that some terminology may be unfamiliar, and our goal is to clarify these terms to enhance your understanding and empower you as a homeowner.
Whether you are embarking on energy efficiency upgrades, navigating building compliance, or exploring retrofitting options, this glossary serves as a helpful reference guide to ensure you are well-informed throughout your journey.
Accredited Contractor
A contractor who has been officially recognised or certified as meeting specific standards set by the accrediting body, typically under schemes such as TrustMark or PAS 2030.
Assessment (PAS 2035)
A detailed check of your home to understand how energy efficient it is. It follows official guidelines (PAS 2035) and helps create a personalised plan to make your home warmer, greener, and cheaper to run.
Building Regulations
National standards that apply to most building work in the UK, ensuring safety, energy efficiency, and accessibility. It is the homeowner’s responsibility to ensure compliance with these regulations.
Competent Persons Scheme (CPS)
A government-approved scheme allowing registered tradespeople to self-certify certain types of building work for compliance with Building Regulations in England and Wales.
Digital Model
A digital replica of your home is used to simulate energy improvements, predict costs and savings, and assess impact on the EPC rating before any physical work begins.
ECO4
The fourth phase of the Energy Company Obligation (ECO) scheme, designed to support energy efficiency upgrades in UK homes, particularly for low-income and vulnerable households.
Energy Performance Certificate (EPC)
A document that rates the energy efficiency of a property on a scale from A (most efficient) to G (least efficient), required when building, selling, or renting a home.
Insurance-Backed Guarantee
An insurance policy that protects consumers by honouring the original guarantee issued by a contractor or installer if they cease to trade.
PAS 2030 sets standards for installing energy efficiency measures – it’s a certification for installers.
PAS 2035 outlines a broader retrofit process, including assessment, design, and monitoring – it’s not a certification but a framework for best practice.
(PAS 2035 is typically used alongside PAS 2030.)
Post-Installation Monitoring
Ongoing evaluation after work is completed to ensure the energy efficiency improvements are performing as expected.
Retrofit
The process of upgrading an existing building with new technology or measures to improve energy efficiency, comfort, or sustainability.
Retrofit Coordinator
A qualified professional responsible for managing the end-to-end retrofit process in accordance with PAS 2035, ensuring quality, compliance, and customer support.
TrustMark
TrustMark is the UK Government-endorsed quality scheme for work carried out in and around the home. It helps consumers find trustworthy tradespeople and ensures that work meets high standards of quality, safety, and customer protection.
With You All The Way Service
A term used by Retrogreen to describe its comprehensive approach to home improvements, supporting homeowners from consultation and assessment through installation and post-installation monitoring.
The NHIC would like to thank the WG2 Consumer Voice members for their contributions to this guide.
Please note that this guidance document, produced by the NHIC, was correct when published. However, information and regulations may have changed since the publication of this document. Therefore, it is always advisable to seek the most up-to-date information and expert advice before making any decisions related to insulating your home.
Copyright National Home Improvement Council 2025.
