In the drive toward sustainable buildings and net-zero targets, understanding energy ratings has never been more important. Two of the most commonly referenced rating systems in the UK are the Energy Performance Certificate (EPC) and NABERS UK. While both serve the purpose of evaluating energy-related performance, they are fundamentally different in what they measure, how they are calculated, and the value they provide to building owners, tenants, and investors.
This article provides a comprehensive comparison between EPC and NABERS UK, explains their respective roles, and highlights why NABERS UK is quickly gaining momentum in the UK’s commercial real estate sector.
What is an EPC?
The Energy Performance Certificate (EPC) is a legal requirement for commercial buildings in the UK that are constructed, sold, or leased. Introduced under the Energy Performance of Buildings Directive, EPCs provide a rating of a building’s energy efficiency based on its design and construction.
EPC ratings range from A+ (most efficient) to G (least efficient) and are based on the building’s theoretical performance under standardised usage conditions. The calculations are done using software models such as SBEM (Simplified Building Energy Model) or DSM (Dynamic Simulation Modelling).
Key Characteristics:
Asset-based: Focuses on the design, materials, insulation, and fixed services (e.g., HVAC).
Modelled data: Based on assumptions, not real energy usage.
Static: Only updated when a building is sold, leased, or significantly modified.
Compliance-driven: A legal requirement under MEES (Minimum Energy Efficiency Standards).
While EPCs provide a valuable baseline for energy efficiency, they have limitations. Since they don’t account for how a building is actually operated, two buildings with the same EPC rating could have dramatically different real-world energy consumption.
What is NABERS UK?
NABERS UK (National Australian Built Environment Rating System UK) is a performance-based rating system that measures the actual energy use of a building over a 12-month period. It was launched in the UK in 2020 by the Better Buildings Partnership, following the success of NABERS in Australia.
NABERS UK focuses on the operational performance of commercial office buildings. Ratings are expressed in stars, from 0 to 6, with 6 being market-leading performance.
Key Characteristics:
Operational-based: Measures real, metered energy consumption.
Dynamic: Reflects ongoing performance, updated annually.
Benchmark-driven: Compares against national standards and peer buildings.
Tenant & owner influence: Measures base building or whole building, depending on scope.
Unlike EPCs, NABERS UK offers a clear picture of how efficiently a building is actually being run, which makes it much more relevant for ESG reporting, tenant engagement, and sustainability strategy.
EPC vs NABERS UK – What’s the Difference?
Feature
EPC
NABERS UK
Type of Rating
Asset-based
Operational-based
Building Type
Residential & Commercial
Commercial Only
Purpose
To assess energy efficiency of a property’s structure and systems at a point in time
To assess energy efficiency of a property’s structure and systems at a point in time
Mandated For
Required by law for all commercial properties when built, sold, or leased
Voluntary (but increasingly adopted for ESG and investor transparency)
Scale / Rating System
A+ to G scale based on CO₂ emissions and energy modelling
0 to 6 star rating based on actual performance vs benchmarks
Methodology
Calculated via SBEM or DSM (using standard assumptions)
Based on metered energy data, weather-normalised, adjusted for occupancy
Benchmark Basis
Against modelled notional building
Against national benchmarks from real building data
Transparency
Doesn’t reflect actual operation or tenant impact
Clear, comparable and performance-focused; trusted by investors and tenants
Update Frequency
Typically every 10 years or when improvements are made
Annually (for each 12-month period)
Influenced by Behaviour/Operations?
No – only building design and fabric
Yes – energy management, controls, schedules, operations directly affect score
Legal vs Voluntary – Which Matters More?
EPC: A Compliance Necessity
Under the MEES (Minimum Energy Efficiency Standards), landlords cannot lease buildings with an EPC rating below E. This puts pressure on building owners to maintain acceptable EPC scores, especially in light of proposed tightening of regulations (e.g. raising the minimum to C or B in the coming years).
However, as EPCs are based on modelling, they may not reflect poor operational habits such as 24/7 HVAC use, inefficient controls, or lighting being left on after hours.
NABERS UK: A Performance Differentiator
NABERS UK is not currently mandatory, but its adoption is rapidly accelerating. Investors and occupiers are increasingly demanding evidence of real-world energy performance, particularly in light of:
Net-zero carbon commitments
ESG transparency requirements (e.g., GRESB, SFDR)
Market competitiveness
Leading property owners are using NABERS UK to benchmark and disclose their performance. In Australia, NABERS ratings are often included in lease agreements; the UK is trending in a similar direction.
Why the Industry is Moving Toward NABERS
1. Trust and Transparency
Operational ratings provide a truthful, consistent measure of performance. Tenants and investors know what they’re getting.
2. Alignment with ESG Reporting
NABERS UK is aligned with global ESG frameworks and supports reporting to GRESB, CDP, and others. EPCs, by contrast, are rarely considered in ESG disclosures.
3. Continuous Improvement
Annual reviews of NABERS ratings help track progress over time and identify areas for improvement. EPCs provide no ongoing performance feedback.
4. Market Value
Buildings with high NABERS ratings attract premium tenants, lower vacancy, and stronger investor interest. They’re also more likely to meet future regulatory requirements.
Where the Ratings Work Together
Rather than viewing EPC and NABERS UK as competitors, they can be seen as complementary:
EPC gives you a starting point and is a compliance requirement.
NABERS UK measures actual outcomes and helps you improve them.
Together, they provide a full picture of both the design and performance of your building.
How Bueno Supports Both EPC and NABERS UK
At Bueno, we help building owners, operators, and portfolio managers understand, improve, and sustain their building performance with near real-time data and analytics.
Supporting EPC:
Identify inefficiencies in HVAC, lighting, and equipment operation.
Provide data-backed insights to support retrofit strategies.
Highlight metering or control issues that impact theoretical performance.
Demonstrate improvements that may justify EPC reassessment.
Supporting NABERS UK:
Provide automated tracking of electricity, gas, and water performance.
Detect after-hours use, system drift, and metering issues.
Benchmark actual energy use against baseline models and peers.
Deliver reporting aligned with NABERS requirements, including weather normalisation and base building separation.
Going Beyond Ratings
Deliver continual optimisation insights
Link issues to potential savings
Enable sustainability, operations, and tenant teams to take coordinated action
By aligning data connectivity, modelling, analytics, and reporting, Bueno helps teams not only achieve high NABERS UK ratings but maintain them year after year.
Final Thoughts
With rising energy costs, investor pressure, and the global push to net-zero, commercial real estate can no longer afford to rely on static, theoretical ratings. While EPCs will remain a legal necessity, the future of energy performance in the UK lies in measured outcomes.
NABERS UK is fast becoming the trusted framework for real estate sustainability, tenant transparency, and operational improvement.
Bueno empowers building teams to meet both EPC and NABERS requirements through actionable analytics and near real-time performance insights.
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