Part L of the Building Regulations ("Conservation of fuel and power") sets the carbon and energy performance targets a building must demonstrably meet — and the controls strategy is one of the few elements that can materially move the compliance calculation. The 2021 update (effective June 2022) requires new non-domestic buildings to achieve at least 27% less carbon emissions than the 2013 standard.
Where the BMS sits in the compliance calculation. Compliance is demonstrated through SBEM (Simplified Building Energy Model) or dynamic simulation modelling. The BMS controls strategy feeds directly into this via recognised "compliant" control features: time and temperature zone control, optimum start/stop, weather compensation, demand-controlled ventilation via CO2 sensing, and metering strategy.
Metering requirements. Buildings over a defined floor area threshold must provide automatic meter reading (AMR) with remote data collection, broken down by end use and by tenancy in multi-let buildings. This is a BMS integration requirement as much as a metering hardware one.
The Future Homes and Buildings Standard. Expected to come into force in late 2026, with an anticipated 70-80% carbon reduction compared with the 2013 baseline and effective removal of fossil fuel heating in favour of heat pumps. BMS controls strategies increasingly need to manage heat pump-led systems, which behave very differently from gas boiler plant.
| Part L 2013 baseline | Part L 2021 | Future Buildings Standard (2026+) | |
|---|---|---|---|
| Carbon reduction target vs 2013 | Baseline | 27% (non-domestic) | ~70-80% |
| Heating plant assumption | Gas boiler common | Gas boiler still permitted, higher efficiency | Heat pump / low-carbon led |
| Controls sophistication | Basic zoning, time control | Optimum start/stop, weather comp, DCV | Full performance monitoring |
| Metering | Basic sub-metering | AMR with end-use breakdown | Extended, in-use verification |
Common mistakes
The most common failure is a BMS controls strategy developed in isolation from the Part L compliance calculation — the compliance model assumes control features the installed BMS specification doesn't actually deliver. We also see optimum start/stop and weather compensation specified on paper but never properly commissioned or tuned.
Future outlook
We expect the gap between "as designed" Part L compliance and "as operated" performance to become a bigger issue as NABERS UK ratings gain traction, pushing landlords towards continuous BMS-based performance verification.