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

EPC Rating and Scales

Current rating system

Under the current rating system for non-domestic EPCs in Scotland (as implemented in iSBEM_v6.1.e and other government-approved software), the Asset Rating (AR) of a building is equal to the calculated Building Emission Rate (BER), in kgCO₂/m², after being rounded to the nearest whole number.

Revised rating system

Following the revised EPC rating system (as has been implemented in iSBEM_v6.2.a), the AR is calculated as the ratio of the BER to the Standard Emission Rate (SER), in kgCO₂/m², with the result normalised such that the SER is equivalent to an AR of 50, i.e.,

AR = 50 x BER / SER

The AR is then rounded to the nearest whole number.

The SER is calculated by applying a fixed improvement factor of 23.5% to the estimated CO₂ emission rate of a Reference building, i.e., the Reference Emission Rate (RER), in kg/m². In other words,

SER = RER x 0.765

The specifications of the Reference building are described in detail in the revised NCM Modelling Guide for Non-domestic Buildings in Scotland. However, in brief, the Reference building has the same size, shape, and zone activities as the Actual building, but it has fixed specifications for fabric, building services, and fuel irrespective of the fuels used in the Actual building, its ventilation strategy, and whether it is heated only or heated and cooled.

Scale and EPC bands

Figure 1 displays the scale and corresponding energy bands for the current and revised rating systems for Scotland EPC, as implemented in the iSBEM software. In either case, the AR is mapped to an energy band on a rating scale, and both the AR and the band are then displayed on the EPC.

Current rating scale & bands (in v6.1.e) Revised rating scale & bands (in v6.2.a)