1. The Building Regulations 2000. Approved document L2A. Conservation of fuel and power in new buildings other than dwellings. 2006 edition. The Stationery Office. Free download available.
2. BS EN ISO 13789:1999 Thermal performance of buildings – Transmission heat loss coefficient – Calculation method.
3. National Calculation Methodology document – in preparation.
4. IP 17/01. Assessing the effects of thermal bridging at junctions and around openings. Tim Ward. BRE East Kilbride.
Appendix A. Calculation of BER and TER
This appendix sets out the calculation of the emission rates BER and TER used in the Part L2 (2006) Criterion 1 compliance test.
The CO2 variables used in the calculation can be viewed in Vista:
Cse = total System elec. CE
Cst = total Total system CE
Clt = total Total lights CE (assumed to be electrical)
Note that carbon emissions associated with Equipment energy consumption are not taken into account in the BER and TER calculations.
BER calculation
Electrical carbon emissions (Cse and Clt) are subject to adjustment factor Fe as follows (see L2A Table 3):
If power factor < 0.9, Fe = 1.0.
If 0.9 < power factor < 0.95, Fe = 1 - 0.01 = 0.99.
If power factor > 0.95, Fe = 1 - 0.025 = 0.975.
Lighting energy consumption is adjusted with factor F1 as follows:
If there is metering and warning of out-of-range values, Fl = 0.95, otherwise Fl=1.0.
Applying these factors the revised carbon emission figure to be carried forward to the BER calculation is
BER = Cst - (1-Fe)´Cse + Fe´Fl´Clt
TER calculation
Notional building carbon emissions rate,
NER = Cst + Clt
TER = NER * (1.0 – Improvement Factor) ´ (1.0 – LZC Factor)
where (L2A Table 1):
Improvement Factor varies between 0.15 and 0.2, depending on the carbon emissions from the naturally ventilated areas weighted against emissions from the air conditioned areas (0.15 = fully naturally ventilated, 0.2 = fully air conditioned)
LZC Factor = 0.1
