Article 09: NABERS for Britain? Lessons from Australia on Operational Rating

A series mining the PhD thesis "London and UK Office Buildings: Investigating Energy Use and Landlord-Tenant Influences" (Azhari, 2025).

Key takeaway. Australia NABERS scheme rates buildings on what they actually use, makes ratings mandatory for office disclosure and has driven measurable market change. The UK is part-way there with NABERS-UK and the DEC, but missing the policy backbone that made the Australian version work.

Figure

EPC predicts. DEC and NABERS measure.

EPCs rate buildings on standardised assumptions; DECs and NABERS rate them on metered, actual use.

EPC (UK)

Asset rating

EPCs predict on standardised assumptions, so two buildings with identical envelope and services score the same.

• – What it rates: modelled performance
• – Calculation basis: SBEM, standardised inputs
• – Mandatory? Yes, at construction / sale / lease
• – Base / whole split: whole building
• – Refreshed annually? No
• – Useful for retrofit? Limited

DEC (UK public)

Operational rating

DECs measure actual use across the public estate but do not apply to private commercial offices.

• – What it rates: operational use
• – Calculation basis: metered, normalised
• – Mandatory? Yes, public estate only
• – Base / whole split: whole building
• – Refreshed annually? Yes
• – Useful for retrofit? Yes

NABERS-UK

Operational rating

NABERS-UK measures actual use and splits base-building from whole-building, but remains voluntary without a policy backbone.

• – What it rates: operational use
• – Calculation basis: metered, normalised
• – Mandatory? Voluntary
• – Base / whole split: both
• – Refreshed annually? Yes
• – Useful for retrofit? Yes

Comparison across six features: what each scheme rates, its calculation basis, whether it is mandatory, the base/whole-building split, annual refresh and usefulness for retrofit.

One slogan to remember

The simplest way to summarise the difference between EPCs and NABERS is in five words. EPCs predict. NABERS measures.

An EPC scores a building on assumed conditions: standardised use, standardised occupancy, standardised plant performance. Two notional buildings with identical envelope and services receive the same rating. This makes the EPC useful for compliance and for design-stage benchmarking. It also makes it a poor predictor of how much energy any specific building actually consumes, as Article 2 demonstrated.

NABERS does the opposite. It rates a building on the energy it actually consumed in a defined twelve-month period, with adjustments for climate, hours of use and occupant density. The rating moves up and down as the building operates well or poorly. A building can have a five-star NABERS rating one year and a three-star rating the next if its operations deteriorate. That is exactly the property a useful energy rating needs to have.

How NABERS works in Australia

NABERS was introduced in Australia in the late 1990s and became the basis for the Commercial Building Disclosure (CBD) scheme in 2010. CBD requires owners and lessors of commercial offices above a defined floor-area threshold (currently 1,000 square metres) to disclose a valid NABERS Energy rating at the point of sale or lease.

The scheme separates base-building ratings (the parts of the building the landlord controls) from tenancy ratings (the parts the tenant controls) and whole-building ratings (the sum). This separation is crucial in multi-let buildings, because it allows landlords to be held accountable for what they control without conflating it with what they do not.

Australian experience, summarised by Mallaburn and colleagues (2021) in a paper co-authored as part of this thesis, shows that three preconditions were essential for NABERS to drive market change. Political leadership, which kept the scheme stable across changes of government. Adequate financial resources, both for scheme operation and for participants to invest in the upgrades that improved their ratings. And a body of engineering and market-facing expertise with credibility on both sides of the landlord-tenant divide.

The result, over more than two decades, has been measurable. Independent analysis by IPD has shown rent premiums and higher asset values for buildings with higher NABERS ratings, providing a market reward that complements the regulatory requirement to disclose. The Australian Commercial Building Disclosure annual reports document significant year-on-year improvement in the average rating of the disclosed stock.

Where the UK currently sits

The UK has a partial version of this architecture. The Display Energy Certificate (DEC) scheme requires operational ratings for public-sector buildings above defined thresholds, but it does not apply to private commercial offices. NABERS-UK, launched by the Better Buildings Partnership and BRE in 2020, is the more sophisticated emerging option for commercial offices, modelled directly on the Australian original.

NABERS-UK is voluntary. It is a rating tool, not a policy framework. Landlords who use it learn what the Australian landlords have known for years: that operational rating is more useful and more actionable than asset rating. As one of the landlord interviewees in the thesis put it, NABERS-UK is being trialled "considering the new rating scheme could be a more accurate reflection of actual energy use." Another framed the alternative bluntly:

"We need a performance-based scheme that places greater emphasis on energy reduction rather than solely meeting MEES requirements."

The voluntary nature is the limit. Without a regulatory hook, NABERS-UK reaches the landlords who are already motivated and bypasses the ones who are not. This is the same shape as the broader split in commercial real estate decarbonisation between the leading edge and the long tail.

What would have to fall into place

Three policy moves would carry NABERS-UK from voluntary tool to market-shaping framework.

The first is mandatory disclosure at a defined size threshold. Article 1 covers the case for the 1,000 square metre cut-off used in the UK 2021 consultation. Mandatory disclosure would also need to specify the rating tool (NABERS-UK or successor), the reporting cadence and the enforcement architecture.

The second is a minimum performance bar. Disclosure alone names the problem. A minimum bar fixes a floor below which a building cannot transact. The Australian experience suggests that a relatively low initial bar, ratcheted up on a published schedule, is more effective than a high initial bar that the market cannot meet.

The third is the supporting infrastructure: trained assessors, accreditation, data validation, an appeals process. Australian NABERS relies on a relatively small number of accredited assessors who maintain market credibility through training and a defined methodology. The UK would need to build comparable capacity.

The 2026 National Buildings Database (DESNZ), which the author contributed to, shows what an operational rating would have to engage with at scale. Mains gas dominates the office heating mix. Around 96 per cent of General Office and Office (Local Authority and Central Government) floorspace nationally uses mains gas as its primary heating fuel. The implication for any operational rating scheme is straightforward: a rating that does not track and reward the shift away from gas will miss the largest single decarbonisation lever in the office sector. NABERS-UK ratings are sensitive to operational energy consumption and therefore to fuel switching at the asset level, but the policy framework around the rating has to be designed to drive that switch rather than merely measure it.

The thesis position, in line with Mallaburn and colleagues (2021), is that these three moves are necessary but not sufficient. They also need political leadership across multiple parliaments, which is the precondition that has proved most fragile in the UK.

Why this would not displace the EPC

Adopting NABERS-UK does not require abandoning the EPC. The two ratings answer different questions. The EPC continues to do the job it was designed for: comparing buildings on the basis of their envelope and services, holding occupancy constant. NABERS does the job the EPC was never designed for: measuring what a building actually uses.

In a complete framework, the two coexist. The EPC at the point of construction or refurbishment, governing the design-stage decisions. NABERS at the point of sale, lease and annual operation, governing the market for actual performance. Together they cover the building from cradle to operation. Article 2 made the case for the pairing. This article makes the case for completing it on the operational side.

There is a smaller, related question about how DEC and NABERS-UK would coexist. DEC has the advantage of being in operation across the public estate. The pragmatic answer, suggested in one of the interviews, is to keep DEC for the public estate while introducing NABERS-UK for the private commercial sector, with a path to convergence over time.

What the data does not see

The Australian context (climate, lease structures, tax treatment, regulatory bodies) is not directly comparable to the UK. Policy transplants need translation. NABERS-UK is still a young scheme. Uptake data, calibration and base-building boundary rules are likely to evolve quickly. This article relies in places on the author co-written Mallaburn and colleagues (2021) paper, which should be cited and disclosed. Operational rating critics raise concerns about data quality, tenant cooperation and gaming. Those deserve their own treatment, not a single paragraph. Policy outcomes depend on enforcement and incentives. Comparing schemes on design alone misses the implementation story.

The next article stays in the policy and benchmarking space. Article 10 looks at the UK office energy benchmarks (ECG-19, CIBSE TM46) which are based on a 1992 study, and at what an empirical refresh based on the Greater London data would look like.

Limitations

The Australian context (climate, lease structures, tax treatment, regulatory bodies) is not directly comparable to the UK. Policy transplants need translation. NABERS-UK is still a young scheme; uptake data, calibration and base-building boundary rules are likely to evolve quickly. The piece relies in places on the author co-written Mallaburn and colleagues (2021) paper, which should be cited and disclosed. Operational rating critics raise concerns about data quality, tenant cooperation and gaming; those deserve their own treatment, not a single paragraph. Policy outcomes depend on enforcement and incentives. Comparing schemes on design alone misses the implementation story.

References

• Azhari, R. (2025) London and UK Office Buildings Investigating energy use and landlord/tenant influences. Doctoral thesis (Ph.D), UCL (University College London). URL: https://discovery.ucl.ac.uk/id/eprint/10204821/

• Mallaburn, P., Azhari, R., Fawcett, T., and Topouzi, M. (2021). Australian non-domestic buildings policy as an international exemplar. Buildings and Cities, 2(1), 318-335. doi:10.5334/bc.114. Available at: https://doi.org/10.5334/bc.114

• Bannister, P. (2012). NABERS: Lessons from 12 Years of Performance Based Ratings in Australia. Available at: https://www.buildingrating.org/document/nabers-lessons-12-years-performance-based-ratings-australia

• Australian Government (2017). Commercial Building Disclosure: the legal framework. Available at: https://www.cbd.gov.au

• Better Buildings Partnership (2020). BBP Spearheads Launch of New Energy Rating Scheme for UK Offices (NABERS-UK). Available at: https://www.betterbuildingspartnership.co.uk/bbp-spearheads-launch-new-energy-rating-scheme-uk-offices

• BRE (2021). NABERS UK Energy for Offices: scheme handbook. Available at: https://bregroup.com/services/standards/nabers-uk/

• BEIS (2021). Performance-based policy framework for rating the energy and carbon performance of commercial and industrial buildings above 1,000 m2 in England and Wales. Available at: https://www.gov.uk/government/consultations/performance-based-policy-framework-in-large-commercial-and-industrial-buildings

• Evans, S., Fennell, P., Humphrey, D., Liddiard, R., Oraiopoulos, A., Palmer, J., Ruyssevelt, P., Shamsi, H., Amrith, S., and Steadman, P. (2026). National Buildings Database Phase 2. Department for Energy Security and Net Zero. Available at: https://www.gov.uk/government/publications/national-buildings-database-phase-2-understanding-great-britains-buildings

Read next

• Article 2: Why EPCs Do Not Tell You How Much Energy a Building Uses.

• Article 10: Time to Retire ECG-19?

About this series

This article is part of a fifteen-piece series adapting the 2025 PhD thesis "London and UK Office Buildings: Investigating Energy Use and Landlord-Tenant Influences" (Azhari, 2025) for a mixed academic and industry readership. The empirical findings draw on the 3DStock model of 6,038 office Self-Contained Units in Greater London with metered energy data for 2017, supplied by BEIS under a data-sharing agreement, alongside the Better Buildings Partnership Real Estate Environmental Benchmark. The qualitative findings draw on semi-structured interviews with seven major UK property organisations, conducted during the 2021 lockdown. Interviewees and their organisations are anonymised by role and organisation type. Please cite the original thesis for academic use.

Author. Rayan Azhari completed his PhD at the UCL Bartlett School of Environment, Energy and Resources in 2025, supervised by Paul Ruyssevelt and Kathryn Janda. The research was supported by the EPSRC Centre for Doctoral Training in Energy Demand (LoLo) and UK Research and Innovation through the Centre for Research into Energy Demand Solutions.

Other articles in the series. Article 1 The 30/85/89 Problem; Article 2 Why EPCs Do Not Tell You How Much Energy a Building Uses; Article 3 Eighteen Per Cent; Article 4 Mapping the Stock; Article 5 Height, Age and the Fuel Question; Article 6 The Split-Incentive Problem; Article 7 Green Leases and Service Charges; Article 8 From 38 to 73 Per Cent Energy Savings; Article 9 NABERS for Britain; Article 10 Time to Retire ECG-19; Article 11 Can London Speak for England and Wales; Article 12 The Hybrid-Work Footprint; Article 13 Why I Used Linear Regression Over Random Forest; Article 14 Vertical Postcodes; Article 15 What Is a Building?