UK data centres face extremely high and constant energy density, a strong expectation of sustainability certification, and a statutory energy compliance regime (Part L) not originally written with data halls in mind.
BREEAM's role for data centres. BREEAM assesses data centres under the BREEAM Other Buildings family, evaluating energy, water, materials, waste, pollution, land use and management, contributing credits to an overall rating (Pass to Outstanding). The Energy category typically carries the heaviest weighting given the building type's intensity, where PUE target and cooling efficiency have the most influence.
Part L and the data centre problem. Part L's methodology was developed around conventional occupied building types, and data centres — with IT load dominating consumption — sit awkwardly within it. In practice, compliance focuses on non-IT building services (office/support areas, fabric, base-build plant efficiency), while IT load sits outside Part L's direct scope but very much within BREEAM's Energy category.
Cooling and PUE as the dominant design lever. UK climate, with meaningful hours per year suitable for free cooling via air economisation, makes this genuinely effective compared with hotter climates. Hot/cold aisle containment and IT equipment inlet temperature strategy aligned with ASHRAE guidelines all contribute to PUE performance.
Metering, monitoring and the BMS. Both BREEAM and good practice require granular energy metering — sub-metered by mechanical, electrical, IT load and per-tenant — feeding a monitoring platform capable of calculating and reporting PUE on an ongoing basis.
| BREEAM | Part L | |
|---|---|---|
| Status | Voluntary, client/investor-driven | Statutory |
| Scope | Whole facility including IT-supporting infrastructure | Primarily building fabric and non-IT services |
| Key metric | Category credits (Pass to Outstanding) | Target Emission Rate vs Notional Building |
| Data hall/IT load treatment | Directly assessed | Largely outside direct scope |
| Driven by | Investor ESG requirements, planning conditions | Statutory Building Regulations approval |
Common mistakes
The most common gap is treating BREEAM as a bolt-on assessment conducted after the engineering design is fixed, rather than a set of credit targets shaping cooling strategy from concept design onward. A second issue is confusing Part L compliance with a client's PUE or BREEAM Energy target.
Future outlook
We expect increasing regulatory attention on data centre energy consumption given the sector's rapid growth to support AI and cloud workloads, and embodied carbon growing in weighting as operational efficiency improvements plateau.