The Home Energy Model era needs a new Energy Assessor Scheme

Vulcan has been approved by the UK Government Ministry of Housing, Communities and Local Government (MHCLG) as an OCDEA (On-Construction Domestic Energy Assessor) accreditation scheme for England and Wales.

The Home Energy Model (HEM) marks a step-change in what an energy assessment can be. The bottleneck won’t be the calculation engine — it will be input quality, assessor capability, and how quickly errors are caught.

We're becoming a scheme because we think schemes must do more than audit after the fact. They need to prevent avoidable problems.

TL;DR

HEM (delivered via MHCLG’s ECaaS API) creates more detailed, testable assessments - but increases the risk of inconsistency.

Scheme access is the gateway to regulated HEM calculations.

The current “sample audit” model finds issues late; HEM makes that gap bigger.

Vulcan’s approach is to integrate software + training + QA so quality improves continuously, not just when a case is audited.

The HEM era changes what “good” looks like

The recently announced £15b Warm Homes Plan — and the deadline for Minimum Energy Efficiency Standards — both depend on reformed, accurate Energy Performance Certificates.

HEM is the key methodology change. Unlike SAP (new dwellings) and RdSAP (existing dwellings) — monthly models with opaque, outdated assumptions — HEM is open source and sub-hourly, capturing the dynamic way homes use energy through the year.

That enables HEM to:

Identify peaks in heating demand or internal temperatures
Explicitly model interactions between heat pumps, controls, solar, and batteries
Provide better evidence to make and validate retrofit decisions

Access to HEM for building regulations (including reformed EPCs and the Future Homes Standard (Part L)) will be through ECaaS (Energy Calculations as a Service) — an API provided by MHCLG.

ECaaS will only be accessible via Energy Assessor Schemes. The calculation engine is common; what differs is the interface and process used to create, validate, evidence, and lodge assessments.

The current scheme model finds problems too late

Accreditation schemes exist to ensure assessors are competent and to monitor certificate quality. Today, that mostly happens via sampling:

Scheme Operating Requirements set a 2% minimum audit requirement, with defined audit selection logic.

Sampling can work — but it creates an obvious gap: quality is often discovered late (when evidence is requested, when a plot is selected, or when a discrepancy is found). That means rework, delays, and inconsistency.

HEM increases the risk of avoidable mistakes. More detailed inputs and wider use cases create more opportunities to be inconsistent, making the “find it later” model costly.

Our view is simple: in the HEM era, schemes shouldn’t just police. They should prevent.

Vulcan’s approach: prevent issues before lodgement

Before we became a scheme, Vulcan existed for one reason: to make HEM easy to use and learn. HEM’s capability only matters if assessors can use it without drowning in extra work and complexity.

We’ve worked to make HEM fast and practical. Users can import building geometry from CAD, import a SAP PDF or XML, or draw inputs visually (including tracing onto a floorplan). We also made Vulcan usable for AI agent-assisted analysis, increasing the speed and breadth of analysis assessors can conduct.

By integrating quality assurance and training directly with assessment software, we aim to improve productivity, raise consistency, and generate better client outcomes over time.

What we’ve built (so far)

Vulcan has led the way in proactively improving modelling productivity with software — and will now proactively improve quality assurance.

We’ve integrated training and ECaaS lodgement with Vulcan, which now includes:

Dry-run assessments: assessors can test ECaaS workflows and demonstrate competence with HEM input conventions. This complements training and admission processes.
Member-requested quality assurance: Members can request additional support on assessments they are unsure of — making QA supportive, not purely policing.
Batch ECaaS input upload and lodgement: new build is rarely one dwelling at a time. Evidence can be uploaded once, assigned across multiple plots, and submitted to ECaaS in bulk.
Integrated training: Vulcan's software and scheme documentation, as well as a range of official HEM technical specs, are available to logged in users. Content views are tracked, so users can see when there are updates.
Automated pre-submission checks: catching avoidable issues before lodgement. Vulcan warns for unexpected building geometry, or mismatches with prior SAP inputs (if these are uploaded). We’ll continue to enhance these checks to reduce rework and failed audits.

Importantly, these features (outside of the actual ECaaS lodgement) are available to ALL Vulcan users, so everyone can improve their knowledge, and create better assessments.

Founding Member cohort

We’re now opening applications for a founding cohort.

Who this is for (today):

Existing OCDEAs: founding membership is for qualified new-build assessors (via an OCDEA course or prior experiential learning).

What’s included:

Ongoing OCDEA accreditation
Full Vulcan software access for unlimited local scenario analysis
Unlimited ECaaS access for compliance checks
50 ECaaS lodgements per month (producing full compliance documentation)
Small-group training focused on practical HEM modelling, plus access to all our content
A detailed review of your first HEM assessments, plus a generous ongoing allowance of voluntary audited assessments
Access to the Vulcan team and direct input into the Vulcan roadmap across software, training, and QA

If you want to join our founding cohort, you can sign up here.

Not an OCDEA? You can still use Vulcan

For housebuilders, consultants, DEAs and others: our software will continue to be available without Scheme membership. Contact us if you’d like a demo.