Faster beats familiar
The Home Energy Model (HEM) will reward faster workflows, not familiar ones.
As assessors move toward the Home Energy Model (HEM), many will be reassured that their HEM workflow will feel familiar. That may sound comforting, but it is the wrong optimisation target.
In practice, "familiar" means recreating the workflow used for SAP: long forms, lots of fields, and heavy manual data entry. When applied to HEM, which supports more detail and has more analytical value, this approach risks turning a better model into a slower service.
Vulcan takes a different approach. Instead of constructing a HEM model primarily through long-form input, it starts with 3D geometry and combines that with reusable defaults to produce HEM-ready inputs.
Everyone will face a learning curve adopting HEM. Firms that do so with software optimised for "familiar" rather than "faster" will spend more time on input, review, and rework - eroding margins.
The alternative to forms: 3D geometry
Vulcan's 3D geometry builder helps users quickly outline the shape of a building, to create HEM inputs
Vulcan uses two ingredients to create HEM inputs:
- a defaults file, containing reusable assumptions and parameters needed by HEM;
- a geometry file, stored as CSV, containing the shape of a dwelling and variations from the default.
This separation lets assessors focus on creating a dwelling's geometry from a floorplan or CAD export. The CSV can be opened in Excel or Google Sheets and integrated more easily with PHPP or other software.
Vulcan's floor-plan workflow lets users trace rooms visually before validating the full model in 3D.
Vulcan builds on HEM here. HEM provides element orientation, pitch, and dimensions, but not location. Vulcan's geometry file additionally specifies coordinates.
Combining a 3D geometry file with a defaults file has clear operational benefits:
- independent reuse of defaults and geometry files instead of re-entering known assumptions, which cuts repeated input work and batch modelling;
- duplication of repeated geometry instead of redrawing similar storeys, which matters in blocks, terraces, and multi-storey homes;
- less manual field entry for openings and building elements (including when netting areas), which reduces the number of values that need to be typed and checked individually;
- quicker detection of geometry mistakes before a run, which reduces rework later in the process;
- easier import from floor plans or CAD files, which turns existing information into model inputs instead of asking assessors to recreate it manually.
Why the 3D geometry builder matters
HEM already describes many building elements in a structured way, including dimensions, pitch, and orientation. What a geometry-first workflow adds is spatial context: where those elements sit relative to one another, and whether they make sense as a building.
That matters because 3D is not just prettier than a form. It makes review faster and more reliable. Users can check that windows sit in the walls they are meant to occupy, that walls meet floors and roofs properly, that shading is plausible, and that volumes used for thermal and ventilation calculations are not obviously wrong. Instead of checking values such as base_height, height, or frame area fraction as isolated numbers in a table, they can review them in the context of the dwelling.
A geometry-first workflow
A geometry-first HEM workflow is simple in outline:
- start from an existing defaults file or archetype;
- trace or import geometry;
- classify elements and add openings and systems;
- validate the model spatially and resolve warnings;
- run, review, and share the result.
A geometry-first workflow does not remove HEM's complexity. Systems, assumptions, evidence, and judgement still matter. But it does reduce time wasted on repetitive input and avoidable geometry errors.
Why it matters commercially
The transition from SAP to HEM is often framed as a compliance burden. That is understandable, but incomplete. HEM does increase complexity, but it also creates more room for better modelling, stronger validation, and more valuable services.
The operational question is straightforward: how much time and review effort does each model consume?
An assessor using a long-form workflow may still complete HEM jobs, but with higher labour cost and more opportunities for avoidable input error. A geometry-first workflow shifts effort away from repetitive entry and toward review, interpretation, and advice.
Over time, that difference affects margins, turnaround times, QA burden, and the range of services an assessor can offer profitably.
The most competitive HEM tools will not be the ones that merely preserve SAP-era workflows. They will be the ones that reduce the time, rework, and QA burden of creating a model.
If you are planning for HEM delivery, the question is not whether your team can complete a model. It is how much time and margin each model will consume. That is the workflow problem Vulcan is trying to solve.
If you think HEM will make life harder and don't see the benefits, you're probably not approaching it correctly, and should speak to us.