Table of Contents
1. What is a Display Energy Certificate?
2. Why Display Energy Certificates are required?
3. Buildings requiring a Display Energy Certificate
4. When Display Energy Certificates are required?
5. What an advisory report contains?
6. Penalties for not having a DEC certificate
7. Pre inspection questionnaire
A Display Energy Certificate is a document that shows the energy performance of a building. The calculation is based on the actual energy consumption of the building as recorded annually over a period of up to three years. The Display Energy Certificate includes a Display Energy Rating and an Advisory report. DEC certificates come with a validity of one year and it must be updated annually by an accredited DEC assessor.
Display Energy Certificate (DEC Certificate) has been introduced as a Government initiative to raise public awareness of energy consumption and inform incoming visitors about a building’s energy usage. The DEC Certificate displays an energy rating on a scale of A to G.
Any building that is wholly or partly in use by public authorities or public service institutions are required by law to produce a DEC certificate and an advisory report. Since these buildings are support a large number of occupants and are frequently visited by members of the public, a DEC certificate must be displayed at all times.
These public authorities include:
From 9 January 2013, it is mandatory for all public buildings of 500 m2 or bigger to display a DEC certificate in a prominent place so that it is clearly visible to the public.
The advisory report includes a series of recommendations for possible improvements ranging from zero and low cost operational management improvements to the more expensive measures such as changing building fabric or services and the addition of low and zero carbon (LZC) technologies.
The report is intended to help the occupier identify factors that could improve the building’s energy management and thus reducing energy use and CO2 emissions.
The recommendations are categorised according to their respective payment periods as follows:
A penalty charge of £ 1500 by the local authorities may be applicable to buildings that fail to produce a DEC certificate at all times. Failure to commission the required documents in addition to the fine may account for further offences and hence more fines.
What factors effect the display energy certificate rating?
DEC ratings of buildings are hugely influenced by the gas and/or energy consumption and are totally different to EPC and SBEM calculations where the software makes a number of assumptions based on the input data and calculates the energy consumption resulted in heating, hot water and lighting and ventilation based on a standardised model. This leads to a discrepancy between the rating calculated and the actual energy consumption as the calculations are independent of energy consumption by cooking, electrical appliances and other utilities.
Display Energy Certificate (DEC) ratings are generated by calculations based on the actual meter readings and no assumptions are made and nothing is compared to standardised models.
Despite this, the DEC rating is still not a perfect model as one of its main defects is that the effect of renewable energy cannot be shown in the software if the units are not sub-metered. It means that if a CHP exists in a building, its presence will not benefit the building as it cannot be input into the software unless it is linked to a separate meter and the gas and electricity readings can be seen.
Another major problem with the DEC is that when the DEC calculation is generated, the software automatically compares it to the benchmark to give a rating. However, some facilities might be present in the sites which are not included in the benchmark and unless these facilities are sub-metered they cannot be excluded from the calculation causing it to show an energy rating which is much worse than the building’s actual rating.
Meter readings are the only form of data that can be fed to the DEC software. However, when it comes to the advisory report it all seems a bit complicated as the assessor needs to include all the systems that are present in the site and identify the system conditions briefly. The recommendation report, however, has no effect on the DEC rating as meter readings would be independent of the condition of the building’s utilities. For instance, even if the conditions of utilities are very good in a building, it can still get a poor rating if the meter readings are high and vice versa.
The only factors that affect DEC are shown below:
Gas and/or electricity consumption, total floor area of the building, building type and benchmark, metered renewable energies.
Similar to other energy assessments such as SAP, EPC and SBEM, DECs are created for comparison purposes only so it is possible to only compare ratings of sites with identical applications. For instance you may compare the DEC rating of Swimming pool A to Swimming Pool B but not to a school, even if it is in the same area. DECs also cannot be compared with SAP or EPCs as they are two completely different certificates and employ completely different calculation methodologies.
Display Energy Certificates are renewed energy year and therefore it is possible to monitor and compare the energy consumption of consequent years and observe improvements. Also, the recommendations included in the DEC are very useful as some of them are either cost free or inexpensive to adopt and so improvements are possible even in a span of few years.