Benchmarking your building’s
operational performance: Three key rating tools

Sustainability and energy performance are central elements to the UK government’s goals of achieving net zero emissions by 2050 and tackling inefficient energy use in commercial buildings. As well as a growing priority for tenants and buyers, this trend reflects the ambitions of many building owners and managers to improve their own sustainability and efficiency metrics across their portfolio.

Regulations around asset ratings such as Energy Performance Certificates (EPCs) are being slowly tightened, with the intention for all rented non-domestic buildings without a valid exception to have reached an EPC B rating by 2030.

However, stricter asset ratings are only one half of the government’s strategy for large commercial and industrial buildings. The other half is the impending introduction of an annual operational performance rating, the disclosure of which will be mandatory.

So, what’s the difference between asset rating and operational performance?

Luke Cleary, director of CSR Sustain, says: “When assessing the energy performance of your building, there are two distinct categories of benchmarking: the asset rating and the operational performance rating.

“The former is a measure of the energy efficiency of your building as was initially designed and is conducted before any occupants have started to move in. It is a theoretical assessment of the energy performance potential of your building’s fabric and services. And while it’s an important tool for a building’s first-time purchasers or tenants, it cannot account for overall energy efficiency while the building is in use.

“For a full understanding of your building’s total energy performance, it also needs an operational performance rating, which is assessed while the building is occupied over a specified period, and benchmarked against similar constructions.”

While asset ratings allow you to compare the original build quality, operational performance ratings assess emissions caused by a wider range of factors, from user behaviour to unregulated energy consumption.

"A high operational performance rating can provide owners with a significant competitive advantage as it reflects lower operating costs, an improved indoor environment, higher user satisfaction and better sustainability credentials, which all result in the building retaining more value over time."

Gary Cleary - MD at CSR Sustain

He continues, “This provides further incentive to make continuous improvements beyond the original design in order to reduce energy bills, cut carbon emissions and turn the building into a more attractive prospect for both potential occupants and investors.” Let’s examine three key operational performance benchmarking tools that can apply to your commercial building.

Display Energy Efficiency Certificate (DEC)

Required by UK law to be displayed in many public sector buildings, the DEC discloses the building’s energy efficiency, rated from A (most efficient) to G (least efficient). Owners are expected to display it publicly, such as in the main entrance, as it’s intended to encourage them to improve their rating.

The DEC rating is primarily based on the total energy consumption of the building over a 12-month period. This includes electricity, gas, and other forms of energy used for heating, cooling, lighting, and other building operations.

Its key metric is Energy Use Intensity (EUI), which represents the energy consumed per unit of floor area. This is calculated as the total energy consumption divided by the total floor area and is typically expressed in kWh/m²/year.


DEC ratings are valid for 12 months and must be renewed annually, ensuring that the assessment reflects recent energy performance.  Alongside the rating, DEC reports often include recommendations for energy efficiency improvements, allowing owners the chance to take steps to enhance their rating the following year.

BREEAM In-Use Energy Rating

Administered by the Building Research Establishment (BRE), BREEAM stands for the Building Research Establishment Environmental Assessment Methodology.

Designed to assess the long-term sustainability of a building project, BREEAM In-Use allows owners and managers to prioritise energy efficient investments based on a broad range of performance data.

As well as examining energy use, BREEAM In-Use looks at the building’s water use, materials, transport, pollution, the health and well-being of occupants and the management of the site and its surroundings.

Buildings are assessed on a star rating from zero (unclassified) to six (outstanding), while certification also serves as an educational tool to promote best practice and knowledge sharing regarding sustainability in the built environment.

National Australian Built Environment Rating System UK (NABERS UK)

NABERS UK is a relatively new rating system to the United Kingdom, coming as an adaptation of the successful Australian NABERS programme.

NABERS UK differs from BREEAM in that it focuses solely on energy performance – making it a simpler standard for specifically assessing operational energy and carbon emissions.

Assessed over a 12 month period of actual energy consumption data, it offers different levels of granularity depending on building type and industry sector, and is usually rated between one star (poor) to six stars (market leading).

The system promotes transparency and accountability across the commercial real estate industry, and is being considered as part of a UK government consultation to mandate operational energy ratings for large commercial offices.

Start tackling your energy efficiency and carbon emissions now

As the government continues its consultation on mandating an operational performance rating, there are several steps that you can take today to help prepare your own portfolio. To discuss how we can support your commercial real estate strategy, contact our experts now.

Let’s talk energy:
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