Commercial Energy Performance Certificates (EPC)

Our EPC process

At KJ Tait, our commercial EPC process is led by building services engineers who understand how design, operation and maintenance influence a building’s energy performance. This allows us to offer a market‑leading service where assessments are accurate, evidence‑based and focused on achieving the best rating possible.

Unlike basic EPC services, our Level 5 assessors use IES VE dynamic simulation software to model the building using real design inputs. This minimises reliance on default data which can lower ratings and distort investment decisions. Where we identify opportunities for improvement at no additional cost to our Clients, we assess and incorporate these during the modelling stage to ensure the assessment aligns with wider energy strategy requirements.

What we capture during the EPC survey

Our engineers attend site to complete a structured commercial EPC survey, reviewing the following:

• O&M manuals. Full review of mechanical and electrical documentation to confirm plant types, efficiencies and system controls
• Plant rooms and roof spaces. Walk‑through noting HVAC plant ratings, condition and age to ensure accurate modelling of real‑world performance
• Occupied and common areas. Survey of tenant and landlord spaces to record lighting systems, layouts and on‑floor equipment
• Building fabric. Review of windows, roof build‑up and external walls including thermal characteristics where data is available

Once the visit is complete, we build a full IES VE model and simulate a baseline result. If there is scope to improve the rating, we engage with stakeholders to gather further data such as tenant lighting designs or upgraded equipment not recorded in the base build O&Ms. For Clients targeting EPC B or net zero outcomes, we can integrate modelling with your wider net zero consultancy services to ensure the EPC reflects future‑ready performance.

Where operational performance is a concern, our approach can also align with TM54 operational energy modelling to provide greater confidence in both EPC and real‑world outcomes.

EPC Registers

Following internal quality checks, our accredited assessors lodge the commercial EPC on the relevant national register. These are the official public records for commercial EPCs:

England & Wales non‑domestic EPC register

Scotland non‑domestic EPC register

EPC Exemptions

A commercial EPC is generally required when a building is sold, leased or newly constructed. However, some building types are exempt from assessment. Common exemptions include:

• Temporary structures intended for use for less than two years
• Places of worship
• Detached buildings under 50 m² that are not dwellings

Where Clients are unsure, our assessors can advise whether an exemption applies or whether an EPC is legally required. For a practical example of an improvement pathway, see our Oceana House case study.

Why choose KJ Tait

Choosing KJ Tait means working with a team of building services engineers who approach commercial EPCs with technical depth and practical insight. Our focus is on delivering accurate, defensible EPC ratings that support transactions, portfolio strategy and net zero planning.

• Level 5 accredited assessors. Experienced in modelling complex non‑domestic buildings using IES VE
• Engineering‑led surveys. Detailed assessment of fabric, HVAC, controls and lighting to minimise default data
• Accurate, defensible results. Clear inputs and assumptions aligned with current national methodologies
• Upgrade pathways. Evidence‑based recommendations to improve ratings and protect asset value
• UK‑wide capability. Accredited to deliver commercial EPCs across England, Scotland and Wales

Frequently Asked Questions

Key contact

Paul Miller
Chartered Engineer
CIBSE Level 5 Energy Assessor

Email: paul.miller@kjtait.com