Is it necessary to include Operational Ratings on Display Energy Certificates?
The above question is one we’re commonly asked by assessors and in short, the answer is always “yes”, even if there is a compliance gap but why is that the case? Read on to find out more.
What is the Operational Rating on a Display Energy Certificate?
The Operational Rating on a Display Energy Certificate (DEC) represents the energy efficiency of the building. This is displayed as a numerical value that indicates a building’s actual carbon dioxide (CO₂) emissions over the past 12 months. This is shown on an A to G scale with A being the lowest CO₂ emissions (best) and G being the highest (worst).
Government Guidance on Operational Ratings
The Operational Ratings (ORs) on a Display Energy Certificate (commonly referred to as the ‘histogram’) should always be included, even if there is a compliance gap. This is outlined in the methodology documentation that all DEC assessors should be familiar with, as below:
The 2008 government DEC methodology states:
“The total CO2 emissions histogram indicates for the current assessment year, and for the two preceding assessment periods”.
“Energy assessors will use the DEC or Advisory Report unique Report Reference Number (RRN) to check and receive previous certificates, recommendations, or advisory reports. This enables the energy assessor to include any Asset Rating or Operational ratings from the preceding years in the Display Energy Certificate being .” ¹
The 2015 government DEC guide states:
“After first renewal of a DEC and in subsequent years, the certificate must display the OR for the previous two years, as long as the building has not undergone a change of use or occupier during that time…”
“…the DEC must contain…the operational ratings for the building expressed in any certificates displayed by the occupier during the last two years before the nominated .” ²
Applying the rules
Buildings with a floor area over 1000m2:
Where a building has a total floor area over 1000m2, the DEC is valid for 12 months. If you are reviewing a building with a floor area of more than 1000m2, the result should ideally be a histogram with 3 sequential years. Please see the example to the left.
Buildings with a floor area between 250m2 and 1000m2
Where the building has a total floor area of between 250m2 and 1000m2, the DEC is valid for ten years. If you are reviewing a building with a floor area between 250m2 and 1000m2, the result should ideally be a histogram with three assessment years over a 30 year period.
Exceptions to the above
In the event that three sequential years are not available for a building over 1000m2, the histogram should display the operational rating for the current year plus the next two years that are available (if there are any available).
This could result in a histogram that comprises of non-sequential years (e.g 2024, 2021, 2020).
The example to the right shows a DEC histogram where only 1 previous DEC exists. Therefore only 2 years (not 3 are displayed) and the years are not consecutive.
Even though this would indicate periods of non-compliance, where DECs were not produced, the Operational Ratings should still be displayed.
The methodology documentation available provides sufficient guidance on how DEC’s should be produced, including when and how to include previous year’s Operational Ratings.
In July 2013 a government review of the DEC assessment histogram trend found that:
“The trend information was well liked by both public and private sector organisations. Even those that had made little use of the DEC thought that the trend information was motivational as it showed changes over time….There was a strongly held view that the trend information was more useful than the letter rating as it was able to show more fine grained improvements… [and] was thought to be a better indicator of how the organisation was improving its energy.” ³
These findings are highly encouraging for DEC assessors and encourages them to follow the methodology correctly, ensuring to include relevant Operational Ratings for previous years (ideally from subsequent years if available).
However, if unusual circumstances arise, or if you have any questions regarding the above, do not hesitate to get in touch with the non-domestic support team.