National grid retrofit device for smart gas meters


For some time National Grid Metering has been considering ways in which it could ease the environmental and cost impact of an implementation of smart gas metering in Britain. This has lead to the development of a retrofit device that avoids the need to exchange the meter.

A decision by the UK Government to mandate the introduction of smart metering could lead to an expectation that the whole of the existing meter population would need to be replaced. However, there are millions of metering assets fitted in Britain that still have many years of economic and technical life remaining. In considering whether to scrap those meters, account should be taken of the environmental burden of disposal and the purchase of new meters where it might otherwise have been avoided.

A further issue that could have a major bearing on the financial viability of smart metering and the speed of rollout is the potential stranding of value of assets through premature retirement. National Grid Metering is keen to find a solution that will complement and facilitate an efficient smart meter rollout and identified that a solution that would enable the existing asset to remain in situ could be very attractive.

The government decision whether to require a universal deployment of smart meters across Britain is keenly awaited. Meanwhile a number of government-sponsored residential trials are being undertaken to gauge customer reactions. The trials are being managed by the UK Gas and Electricity Regulator, Ofgem, and early results will inform the government’s policy decision.


The smarter gas meter.

In parallel, the industry is attempting to define communications interoperability and whether the standard smart gas metering solution should incorporate a shut-off valve. The current prepayment meter population is in excess of 2.1million, which is approximately 10% of the British gas meter population. However, over half of the prepayment consumers use the meter in order to manage their lifestyle; they are always in credit and the prepayment valve never operates. The importance of this decision rests in the fact that a requirement for a valve would automatically condemn over 18 million gas meters to the scrapheap.

There are varying estimates of the cost of implementing residential smart metering of between £6 and £16 billion. These include the costs of the ‘stranded’ commercial value in the existing meters that would be prematurely replaced. As a way of mitigating the costs there is a growing interest in lower-cost retrofit devices that can be attached to a significant proportion of the ‘dumb’ UK meter population to make them ‘smarter’.

As the largest and most experienced gas meter operator in Britain, National Grid Metering sought a solution that could provide a non-intrusive retrofit device that could be offered as an alternative to meter replacement and it was from this work that Project IRIS was born.


In partnership with Xemtec, a Swiss spin-off of the privately funded research and development company, CSEM, National Grid Metering has developed a retrofit solution that is non-intrusive and can “read” the meter index at a predetermined time interval, transmitting both readings and consumption to a host system for onward transmission to the gas supplier.

National Grid Metering had considered traditional methods of data capture such as utilising a meter’s pulse output. However, some residential-size meters were not fitted with a pulse unit and some others were found without a working pulse so a need for an alternative solution to the traditional pulse output is needed. A decision was taken to pursue development of a cost-effective serial reading device that gave an absolute reading of the meter index as an alternative means of providing smart metering.

The project is still in its early stages of deployment and the current phase is designed to test data collection and the robustness of back office solutions. These processes will inevitably form an integral part of any large scale deployment. Valuable experience is being gained in both installation procedures and mobile phone (GSM/GPRS) topography.

Early results are encouraging and the ultimate aim of the project is to develop a low-cost retrofit solution that is fit for the purpose and sufficiently robust to be deployed in both residential and industrial/commercial premises. The results from the first phase of the project have proven the technology and steps are now being taken to build a low-cost solution that will also include tamper detection and give the robustness needed in the real world.

The project currently deploys an OCR device that scans the meter index at predefined intervals, interprets each dial and stores the result in an onboard data logger. The OCR device is intrinsically safe and AtEx certified for use in a Zone 0 environment. The logged readings are transmitted over the licence-free 868 MHz low-power radio band to a GPRS gateway that communicates with a server at the Xemtec headquarters in Sarnen, Switzerland. Once received, the data is processed and made available as both readings and consumption data via a secure web portal. Future development will seek to reduce the size of the retrofit device and incorporate the communications gateway local to the meter. Development of an intrinsically safe device is a significant technical requirement that is being carefully managed.

It is an interesting question whether National Grid Metering itself should install and own the retrofit devices. National Grid Metering’s prime objective currently is to ensure that a viable and cost-effective choice for residential metering is made available to customers – the critical issue is to demonstrate that the attachment of a retrofit device to an existing meter overcomes the need to replace the asset before the end of its useful life.


As well as the normal benefits available through AMR there are several additional benefits to be realised by the introduction of IRIS technology:

  • It is non-intrusive and quick to install – there is no interruption to the gas supply, allowing the use of semiskilled labour and releasing valuable, skilled gas engineers for more urgent emergency work.
  • It could help with access problems. Meter replacement programmes have always struggled with the challenge of gaining access when the consumer is not available. IRIS can be fitted in outside meter boxes without the consumer needing to be present.
  • Should a meter incorporating this technology need to be retired early (either through churn or planned asset replacement), the optical device can be removed and transferred to another meter, further reducing National Grid’s reliance on the purchase of new equipment.
  • A retrofit option would allow more customers to more quickly enjoy the benefits of smart metering.
  • New meters could incorporate this technology at manufacture, further reducing the cost of implementing smart metering to the GB market.


This innovative approach could be adopted as an interim or longer-term smart metering solution and enable the benefits of smart metering to reach consumers in a more timely and cost-effective way. National Grid Metering is keen to bring this alternative to the attention of the market as it has the potential to play an important role in reducing environmental costs whilst enabling efficiency benefits.