# Calculating EPR where there are multiple NCM outputs

Where more than one NCM output is produced for a development, which is registered as a single assessment, an area-weighted average should be used to calculate the number of credits to be awarded. This does not apply where the ‘similar buildings’ approach is used.

Each of the energy performance outputs from the NCM output (actual CO2/m2 notional CO2/m2 etc.) must be area-weighted to produce area weighted average values which are entered into the scoring and reporting tool. When applying this method, please include your area-weighting calculations and outputs as supporting evidence.

The following provides an example of an area-weighting calculation for two building areas A and B, each of 500m2, for which separate NCM outputs are available:

For building area A:

Notional building heating and cooling energy demand: 230 mJ/m²

Actual building heating and cooling energy demand: 200 mJ/m²

Notional building primary energy consumption: 300 kWh/m²

Actual building primary energy consumption: 280 kWh/m²

TER: 40 kg CO₂-eq/m²

BER: 30 kg CO₂-eq/m²

For building area B:

Notional building heating and cooling energy demand: 150 mJ/m²

Actual building heating and cooling energy demand: 140 mJ/m²

Notional building primary energy consumption: 200 kWh/m²

Actual building primary energy consumption: 190 kWh/m²

TER: 40 kg CO₂-eq/m²

BER: 38 kg CO₂-eq/m²

Area-weighted values for building areas A and B (of total floor area 1000m2):

Notional building heating and cooling energy demand: 230*500/1000 + 150*500/1000 = 190 mJ/m²

Actual building heating and cooling energy demand: 200*500/1000 + 140*500/1000 = 170 mJ/m²

Notional building primary energy consumption: 300*500/1000 + 200*500/1000 = 250 kWh/m²

Actual building primary energy consumption: 280*500/1000 + 190*500/1000 = 235 kWh/m²

TER: 40*500/1000 + 40*500/1000 = 40 kg CO₂-eq/m²

BER: 30*500/1000 + 38*500/1000 = 34 kg CO₂-eq/m²

These area-weighted values are then used to calculate the overall EPRNC value.

```07 Feb 2022 - Reference to 'BRUKL' amended to 'NCM output' to clarify for non-UK assessments
31 Oct 2018 KBCN clarified. Reference to EPRs and calculation example added```