EM Magazine: Sub-Metering Systems – Getting it Right

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EM Magazine:

Sub-Metering Systems - Getting it Right

Elcomponent MD Bill Gysin looks at getting real value from aM&T systems

Advances in smart metering and networking of both the wired wireless variety have made sub-metering systems easier to install, and more cost-effective too, but that has not necessarily resulted in an increase in performance. If ever there was an energy management device that must be viewed as a complete package, sub-metering (aM&T) systems are that device. Like all systems, they are only as good as their weakest link, and there are many links to consider. Elcomponent celebrates thirty years in the business this year, and in that time everything has changed and everything has stayed the same! It is perhaps a good time to take a brief look at how to guarantee that your investment in sub-metering pays immediate and substantial dividends…

The Data

It sounds obvious, but it still has to be stated that it’s the data that matters most, and it’s not just a question of accuracy, imperative as that may be. It has to be the right data, delivered at the right level of detail, and delivered reliably for years into the future with the minimum of maintenance. That is not just down to the right hardware and a good quality installation. Before those choices are made, the system has to be designed so that the meters are reading the right loads or supplies, ensuring that the picture thus obtained is easily understood and readily provides the information needed to save energy. And remember - a lot of little savings is harder work and generally less effective than a few big savings, so the meters must be installed to follow the money.

The right data then, but also the right frequency of data. 'Half-Hour' interval data is the UK norm and for good reason, it has been shown to be right in the 'Goldilocks Zone', but if your processes need more granularity, make sure your system can provide it. Don't consider anything that cannot at the very least provide 'HH' profiling, and whilst we're on the subject of intervals, the data update interval is also critical. Systems that update their software on a 'day plus one' basis (i.e. the most recent data available is yesterday's) can still provide good basic information, but there is a whole lot they cannot do. As the demand for interactive dashboards continues to grow the case for realtime (or close to realtime) data becomes more and more compelling.

You want to engage with a wider audience to foster energy and carbon awareness? That's tough to do if the best you've got is yesterday's data. If you would like to see alarms and alerts before it's too late 'day plus one' has its drawbacks. The case for a 30 minute update to match the 30 minute meter read interval is not hard to make, and with today's technology it's entirely doable, so why settle for less? The data acquisition system as a whole must be fit for purpose and robust, and there is no 'one size fits all' solution for this. The networking solutions should fit the requirements on the ground cable is cheaper and more reliable than wireless links until you have to dig up the car park, at which point cabling makes no sense. The key is to tailor the system to the application, not the other way round. Tailored solutions work better and are far more cost-effective, and as the data is the foundation of the system, it's worth spending time getting this element right.

The Installation

Installing a sub-metering system isn't rocket science, but it's not easy either. At Elcomponent we've lost count of the number of systems that we've replaced over the last (30) years that never quite worked or sometimes didn't work at all, and not all were badly installed by any means. They just weren't installed and commissioned as well as they needed to be. No two installations are the same of course, but there are some common threads that bind most of them together. Most are a combination of new and existing meters, most are multi-utility, and most involve a variety of meter outputs (pulse, MODBUS, M-Bus etc). Almost all involve a tariff meter connection or two. An extensive list of what can go wrong would take up the remaining pages of this magazine, and would almost certainly try the patience of any readers who have made it this far, so here's a short list of a few of the more common pitfalls…

  • Pulse Values: How hard can it be? Harder than it looks is the answer! The combination of 'units per pulse', 'pulses per unit', imperial and metric units and the sheer inaccessibility of some pre-existing meters means mistakes are easy to make. Religious attention to detail at both installation and commissioning stages is the only antidote.
  • Misidentified meters or loads: Reading meters automatically is one thing. Ensuring that they are all correctly identified is also important!
  • Incorrectly installed or programmed existing assets: The world is full of meters that have been there for years and never worked properly!
  • Tariff meter data connections: The professional sub metering/ AMR installer needs more than qualified staff. They must also hold MPU (Meter Pulse Utilisation) agreements with all the relevant Meter Operators, Meter Asset Managers and Utility providers to allow them to connect legally and properly to tariff meters. Otherwise the tariff meter connections end up as one of those pending jobs that never get done, or worse still are carried out without proper authorisation.

Any one of the above can wreak havoc with accuracy and once confidence is lost, it is difficult to regain. As already stated, accuracy is a key requirement!

Future Proofing

Nothing, it is said, lasts forever, and that is certainly true of M&T software. In fact there is a wider choice of software on offer now than ever before, and as web-based solutions become the norm new 'web tools' have hugely increased the functionality delivered by the latest products. That in turn creates a need for portability at the data level, as users seek to take advantage of the latest and best products available.

This does not alter the fact that aM&T systems must be viewed as a package, but it does mean that all the important data must be readily transportable to whatever software solution fits the client’s needs now and in the future. It should be borne in mind that those needs may change at some point after the initial installation.

The Software

Notwithstanding the desirability of ensuring portability of data, if the right choice is made in terms of software there should be no need to change at least for many years into the future. So how should that choice be made and what factors should be considered?

The core requirement for effective energy management is one of the things that hasn’t changed, but the need to address a wider and non-expert audience is one of those that has. That fact significantly alters the must-have functionality list compared to a few years ago.

The traditional functionality list is as it always has been, but that doesn't mean that it's always present. It's surprising how many products either don't cover the basics, or don't cover them in a confident manner. The list must include easy normalisation of data (one click preferably) because there is a limit to how much can be achieved through waste elimination and the harvesting of the traditional 'low hanging fruit'. At some point the impact of degree days, floor area, occupancy and production (to name but a few) must be assessed, and it must be easy to do.

Similarly, regression analysis must be present to provide additional power to the more usual presentation of consumption and cost profiles. Measurement and verification (M&V) is a relative newcomer but it is increasingly important because it quantifies savings in standard in a repeatable way, which is one of the requirements of ISO50015.

Without the above functionality hard-core energy management cannot be done, so it has to be present, but there are now other ways in which good software is being used to improve energy and carbon performance. The umbrella term often used is 'behavioural change' and it addresses the biggest challenge of them all the impact of people on that performance. It is people who override controls designed to optimize energy use, it is people who switch on heaters and open windows contemporaneously, and it is people who are almost always a significant factor in the gap between expected and actual energy performance in buildings.

The jury may still be out on the best way to encourage a workforce or users of a building to consider the impact of their actions on their organisation's carbon footprint and utility bills, but one thing is certain providing accurate and relevant information in a simple and accessible form is a key component, and the right software can do that very effectively. The term 'dashboard' is used fairly loosely to describe presentation screens that inform stakeholders of various aspects of performance in many key areas, but in the case of energy management the detail is important. Information has to be attractive, accurate, relevant and meaningful, which in the case of Elcomponent's MeterWeb 2 is achieved by allowing an unlimited number of dashboard configs and login credentials to be created. This takes care of the relevance, and considering the subject matter above we can hopefully take accuracy as read, which only leaves 'attractive' and 'meaningful'. The former is to some degree in the eye of the beholder but if the 'standard' presentations are readily customisable, all should be well. Opinions also vary on what is meaningful in this context, but it should be borne in mind that non-expert does not mean stupid, and such favourites as league tables must be available in normalised format or their impact will be limited! However, once the audience is convinced that the data are accurate and fair, interest is much easier to maintain.

If these criteria can be met (and they can) M&T software finds itself with a whole new audience and an additional new role. It has to be up to the task. If it's combined with a properly designed, installed and commissioned metering package it will be.

For more information contact: 

Debbie@elcomponent.co.uk | 01279 503 173 | www.elcomponent.co.uk