Energy Performance of Buildings (Scotland) Regulations 2025: non-domestic buildings research

Introduction

As part of the Scottish Government’s response to the 2023 Energy Performance Certificate (EPC) Reform Consultation, the Heat in Buildings Division (HBD) is revising the Scottish National Calculation Methodology (NCM) for non-domestic buildings with regards to EPCs. The objective of the revision is to align the system for rating the energy performance of non-domestic buildings for EPCs in Scotland with that used for EPCs in England, Wales, and Northern Ireland.

The HBD commissioned BRE to develop a demonstration version of the iSBEM software (iSBEM_v6.2.a) which implements the proposed reforms to the non-domestic EPC in Scotland. This version of the software is aimed to demonstrate the impact of the proposed changes in calculating the rating and energy bands for comparison against those calculated using the current system as implemented in iSBEM_v6.1.e.

This report presents an illustrative comparison between the EPC ratings of five archetypal non-domestic buildings in Scotland when calculated using the current and revised rating systems.

BRE developed the iSBEM software for the UK Government (MHCLG) and have enhanced and updated it continuously since its inception in 2005, following changes in the UK’s National Calculation Methodology, revisions of Building Regulations, and implementation of the EPC.

The iSBEM software is a computer program which calculates a building’s energy consumption for regulated end uses, under standardised operating conditions, for assessments of Building Regulations compliance and certification purposes. iSBEM estimates the monthly and annual energy use and carbon dioxide (CO₂) emissions of a non-domestic building when given a description of the building’s geometry, construction, and building services equipment.