NMO is responsible for metering accuracy: ensuring that meters register the correct quantity of gas consumed.
The measurements taken from the readings of gas meters are used to calculate the amount of energy supplied to your home and will appear on the energy bill sent to you by your supplier(s).
Accuracy of meters is something that the National Measurement Office (NMO) take seriously as it ensures that consumers pay for the amount of energy they actually use and facilitate fair trade and competition. However, the National Measurement Office (NMO) is only responsible for electricity and gas metering accuracy and complaints about billing should firstly be directed to the supplier concerned. The Citizens Advice consumer service can assist you with this and provide independent advice on energy supply. If your supplier is unable to resolve your dispute then the Energy Ombudsman can investigate.
However, although meter accuracy is fundamental to the energy billing process, there are many factors, unrelated to the accuracy of the meter that may significantly change the amount you are required to pay when you receive a bill from your supplier. Some examples of these factors are:
Energy price changes
It is clear that fluctuations in energy wholesale prices will flow through to the consumer. This is of particular impact when energy prices are rising and we have seen, for example, significant increases in the average domestic gas bill. It is critical you consider this factor when assessing the reasons for higher bills.
Estimated or incorrect meter readings
Suppliers are required to read and inspect your meter(s) at least once every two years, although some suppliers may visit more frequently.
Where bills are issued more frequently than actual meter readings are recorded, suppliers can use estimates of energy used, based mainly on past consumption, as the basis of the charges. As there can be a lengthy period between supplier readings, it is important you ensure that the estimated reading is close to that actually recorded by the meter. You can do this by recording the reading on the meter yourself and comparing this reading against the estimate soon after you receive your bill. If a large difference is found, contact your supplier who should make adjustments to your account. If your actual consumption is not similar to that estimated by your supplier the gap will need to be closed at the time the meter is actually read. This may mean that your supplier will require more money for the energy actually used or will arrange some form of refund where use is less than estimated.
There is also a chance that a meter could be incorrectly read. Once again, a quick check of the reading stated within the bill against the register of the meter will ensure that errors are quickly detected.
Changes in consumption
External influences or changes to your circumstances may cause a change in the amount of energy you use.
The many reasons for a change in consumption may include:
- particularly colder or milder seasonal weather causing you to use more or less energy
- a change in circumstances (eg illness, new baby, working at home etc)
- a faulty appliance using more energy than it should because it is not operating correctly
- changing types of appliance (ie moving from gas to electricity or vice versa)
Gas ‘meter accuracy test’
Gas meters are generally reliable and major operational faults are rare. However, if you have considered all of the potential reasons noted above that could have caused a change in your energy bill; there is a chance that your meter may have developed a defect causing it to register inaccurately.
You should then contact your supplier who is required to investigate your complaint and make best efforts to resolve the problem. You may also want to consider contacting Citizens Advice Bureau for independent advice on energy supply.
As a final option when all other routes to settle the problem/dispute have failed, on request, the supplier will make arrangements for the accuracy of the meter to be verified by an independent meter examiner appointed by NMO under Section 17 of the Gas Act 1986.
This is known as a ‘meter accuracy test’ and should be requested through your gas supplier. However, it should be noted that the majority of domestic gas meters submitted for dispute testing are found to be operating within statutory limits.
Gas meter testing
It is impractical to test the accuracy of a gas meter on-site so your supplier (or their agent) will arrange for the meter to be removed and a replacement installed. You should take note of the meter details including the serial number and reading at the time of removal. The meter is then securely packaged and sent to an independent meter examiner for testing in an approved laboratory. Meter examiners are employed by SGS (UK) Ltd under contract to NMO to provide an independent meter examination service.
At the laboratory, your gas meter will undergo a number of tests by the meter examiner to check the performance of the meter and establish whether any fault is present that could affect its accuracy. All consumers have the right to witness their meter being tested if they wish.
After all the tests have been completed, the meter examiner will analyse the results and issue a certificate detailing their findings. The certificate will state if the meter was registering within the prescribed statutory limits (nominally ±2% for UK nationally approved meters and ±3% for MID approved meters).
If the meter is found to be outside prescribed limits, a certificate will be issued stating that the meter was erroneous with the error value stated. If the meter is found to have a fault causing the readings to be unreliable this would also be stated on the certificate along with a description of the fault. Copies of the certificate will be sent to the consumer, the gas supplier and the owner of the meter (if applicable).
Accuracy test process
The following flowchart shows the process for testing gas meters:
After the test
Depending on the findings of the independent meter examiner, which will be stated on the certificate, the supplier will take forward measures to conclude the issue. This may include a plan to either compensate the consumer for over-billing or prepare a payment plan for the consumer where under-billing has occurred.
There is no direct cost incurred by the consumer for testing disputed meters although the supplier may charge for the removal of the disputed meter, the installation of a replacement and transporting the disputed meter to the testing laboratory. This charge will be refunded if the disputed meter is found to be operating outside the statutory limits (ie inaccurately).
Having considered these costs, if you wish to proceed with the meter accuracy test, you should arrange this through your gas supplier.
Potentially lower your gas bills
There are some things you can do right now to ensure you start receiving lower energy bills:
- take and submit your own meter reading rather than accepting an estimated bill, suppliers are only obliged to read and inspect your meter once every two years
- ask your supplier for the cost of energy at different times of the day and ensure that you are being charged at the most appropriate tariff for your manner of consumption and the equipment you have connected
- keep a conscious note of what appliances are switched on and for how long they are on for
- ensure gas appliances are serviced regularly to maintain efficiency
- where practical consider reducing the temperature on the thermostat, adjusting switching times of boiler appropriately, etc
Further energy efficiency advice can be obtained from your supplier or Citizens Advice Bureau.
Gas meter accuracy test reports
Around 3,000 domestic, commercial and light industrial gas meters are submitted for dispute testing each year and NMO publish the results of these tests on a regular basis. NMO does not use this data for any formal purposes other than to initiate action with meter manufacturers and owners, when meter examiners identify systematic faults with certain meter types.
The information within these reports is not intended to represent the overall accuracy of gas meters in Great Britain and the following points should be considered:
- the meters tested were initiated by the consumer or the supplier in circumstances where it was suspected that the meter is measuring erroneously – the sample is not representative of the whole meter population
- only a relatively small sample of meters are tested annually and this needs to be considered against the overall population of gas meters in Great Britain that is in excess of 22 million
- this report includes the results of meter tests of types already identified for policy replacement where residual action to remove populations, of the same type, is ongoing
It is important that these factors are considered in context with the information provided.
If you wish to speak to a member of staff please contact:
Gas metering team
Utilities Business Team
National Measurement Office
Reception 020 8943 7272