Commercial Energy Assessments

SBEM, Dynamic Simulation, EPCs and BRUKL for Non-Domestic Buildings

Straightforward energy compliance, delivered by people who understand how buildings actually work

We provide commercial energy assessments for non-domestic buildings across the UK, covering SBEM (Levels 3 & 4), Level 5 Dynamic Simulation Modelling (DSM), BRUKL calculations, and non-domestic EPCs.

We work with:

Developers and commercial property owners
Architects and design teams
Building services and MEP engineers
Contractors delivering Part L compliance

Clients come to us when they want clear, reliable compliance outcomes without confusion, over-simplification, or last-minute redesigns. Our background is in energy and building performance, so assessments are based on how buildings are actually designed and serviced, not treated as a box-ticking exercise.

In simple terms, we help you choose the right assessment method early, meet regulations properly, and understand what the results mean for your project — technically and commercially.

Unsure which route applies? Let’s talk early.

What We Do – and Why It’s Important

Most commercial buildings in England and Wales must demonstrate energy performance when they are:

Newly built
Significantly refurbished
Sold or let

These requirements link directly to Approved Document Part L2 compliance, Building Control approval, EPC ratings, and Minimum Energy Efficiency Standards (MEES). If the energy assessment is poorly scoped or incorrectly modelled, it can lead to:

Delays at Building Control
EPC ratings that do not reflect the building design
Costly redesign late in the programme
Increased compliance and enforcement risk

Our role is to make sure the right assessment approach is chosen early and that the modelling reflects how the building is actually designed and serviced.

We’ll tell you honestly whether SBEM is enough

SBEM Energy Assessments (Levels 3 & 4)

SBEM (Simplified Building Energy Model) is the government-approved method used for most non-domestic buildings. It applies to both relatively straightforward buildings and more complex layouts, depending on size, geometry and services.

SBEM is commonly used for:

Offices and commercial workspaces
Retail and leisure buildings
Education and community facilities
Industrial and warehouse units

What our SBEM service looks like in practice

We review drawings and specifications (or carry out site surveys for existing buildings), build a project-specific SBEM model, and produce:

Design-stage and as-built BRUKL calculations
Non-domestic EPCs for sale or letting
Clear explanations of assumptions and results

We pay special attention to HVAC systems and their efficiencies, ventilation strategies and controls, and the effects of solar shading. These factors are often oversimplified but can significantly influence compliance outcomes.

Level 5 Energy Assessments – Dynamic Simulation Modelling (DSM)

Some buildings are simply too complex for SBEM to represent properly. In these cases, we conduct Dynamic Simulation (DSM), which is considered a Level 5 assessment.

DSM is typically appropriate where:

The building has complex geometry or zoning
HVAC and ventilation systems are design-led or unconventional
Occupancy patterns and internal gains vary significantly
Energy performance is critical to compliance or asset value

Dynamic simulation models building behaviour hour by hour, allowing a much more realistic representation of thermal response, ventilation rates, system operation and controls.

DSM is commonly used for:

Large commercial offices
Complex mixed-use developments
Buildings with advanced or low-energy ventilation strategies

SBEM or DSM? We Help You Decide

One of the most common issues we encounter is the incorrect methodology being applied—either DSM is used unnecessarily or SBEM is applied where it is not appropriate. We advise on this at the start, so you get the right level of assessment without unnecessary cost or risk.

Avoid redesign later — speak to us at concept stage

EPCs and BRUKL – Delivered as One Service

We provide BRUKL calculations and EPCs together, rather than as disconnected exercises. This means:

Design-stage compliance aligns with as-built evidence
EPC ratings reflect the approved design
Fewer issues at handover or letting

It also makes the process clearer for project teams and clients.

Aspect	SBEM	DSM
Calculation approach	Simplified, monthly	Detailed, hourly
Typical building type	Most commercial buildings	Complex or high-value assets
HVAC & ventilation detail	Standardised	Explicit and detailed
Part L / BRUKL	Yes	Yes
EPC generation	Yes	Yes

Our clients typically include:

Commercial property developers
Architects and sustainability consultants
Building services and MEP engineers
Design-and-build contractors
Commercial landlords and asset managers
Public-sector estates teams

We support single buildings and portfolios, at both design and as-built stages.

Early discussion and scoping – understanding the building design and regulatory drivers
Design review (or site survey) – gathering accurate technical information, which includes U-values of the building fabric, air tightness, HVAC zoning and efficiency, lighting, renewable technology and occupancy details.
Energy modelling – SBEM or DSM, as appropriate, using approved modelling tools.
Compliance review – checking assumptions and results
Submission and certification – BRUKL approval and EPC lodgement

Throughout the process, we explain what we are doing and why—no black-box modelling.

Can energy modelling influence design decisions?

Absolutely. Early modelling can inform HVAC, ventilation and fabric choices and avoid compliance issues later.

Let’s Build a Long-Term Working Relationship

Every building is different, and so is every client. At PassiHVAC, we place genuine value on long-term professional relationships, not one-off compliance transactions. Many of our clients return to us because we take the time to listen, understand their priorities, and provide advice that supports their wider objectives, not just the immediate regulatory requirement.

Before any formal appointment, we are happy to have an initial, no-obligation discussion to understand your project, programme and risk profile. We will explain the most appropriate energy assessment route—whether SBEM or Dynamic Simulation—and how this links to Part L approval, EPC outcomes and future MEES considerations. Our aim is to make the process clear, proportionate and aligned with your commercial and technical goals.

Whether you are a developer, consultant, contractor or asset owner, you can expect a service that is responsive, transparent and technically grounded, with continuity of support as your projects and portfolio evolve.

Contact PassiHVAC today to start a conversation. We look forward to working with you, supporting your current project, and building a trusted professional relationship.

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