About HEM Guide

HEM Guide is the UK's independent resource for the Home Energy Model (HEM), the replacement for the Standard Assessment Procedure (SAP). This guide is written by practising energy assessors, not content marketers. Our day-to-day work assessing real properties directly informs every page.

The Author

HEM Guide is published by Guy Smith, Founding Director of Every Property Certificate Ltd (easyepc.org). Guy has been providing energy assessments across England and Wales since 2007 and holds qualifications across all four UK energy assessment disciplines:

• Domestic Energy Assessor (DEA) — qualified to produce Energy Performance Certificates for existing dwellings
• On Construction Domestic Energy Assessor (OCDEA) — qualified to produce EPCs for new-build dwellings and demonstrate Part L compliance
• Non-Domestic Energy Assessor — SBEM (Level 3) — qualified for non-domestic energy assessments using the Simplified Building Energy Model
• Non-Domestic Energy Assessor — SBEM (Level 4) — the highest SBEM qualification level, covering complex non-domestic buildings

This combination of qualifications spanning both domestic and non-domestic assessment, new-build and existing buildings, gives Guy a comprehensive understanding of UK building energy regulations and the practical impact of the transition from SAP to HEM.

About Every Property Certificate Ltd

Every Property Certificate Ltd has been providing energy assessment services across England and Wales since 2007. The company was established shortly after EPCs became a legal requirement for home sales, and has delivered thousands of energy assessments through every major regulatory change since — including the introduction of the Green Deal, changes to Part L in 2010, 2013, 2021, and 2025, and the evolution of SAP from version 2005 through to SAP 10.2.

The business covers the full range of domestic and non-domestic energy assessment: EPCs for existing homes, new-build SAP calculations and Part L compliance, and SBEM assessments for commercial buildings. You can find out more and read client reviews at easyepc.org, including our Trustpilot reviews.

Editorial Approach

HEM Guide is committed to providing accurate, independent, and accessible information. Our editorial principles are:

• Primary sources first — all factual claims are based on government consultations, consultation responses, published legislation, British and European standards, and the HEM open-source codebase
• Independent analysis — we are not affiliated with DESNZ, MHCLG, GOV.UK, BRE, or any accreditation scheme. Where we express opinions, they are clearly identified as such
• Transparency — every content page displays a “Last updated” date and, where applicable, a link to the GOV.UK source document we verified against
• Tiered content — we publish at three levels (accessible, professional, and technical) so that everyone from homeowners to specialist assessors can find information at the right depth
• No paywalls — all content on HEM Guide is free to read

Why HEM Guide Exists

The transition from SAP to HEM is the most significant change to UK home energy assessment in over 30 years. Government consultation documents run to hundreds of pages, the technical papers are scattered across multiple platforms, and there is no single, independent resource that brings it all together in an accessible way.

HEM Guide fills that gap. Whether you are a SAP assessor preparing for the transition, an architect designing to the Future Homes Standard, a developer planning your compliance strategy, or a homeowner wondering what the new EPCs mean for your property, this site aims to give you the information you need — clearly written, properly sourced, and regularly updated.

Start with What is HEM? for an overview, browse the Glossary if you're encountering unfamiliar terminology, or see our Resources page for a curated collection of official documents, tools, and further reading.

Frequently Asked Questions

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