Sub-Metering – Achieving Results

Sub-metering can often be an afterthought during the implementation of most energy saving initiatives.   Detailed monitoring of energy consumption in a building can often lead to significant energy savings through identifying energy waste and facilitating improvements in specifications and behaviours.  Annie Westaway, shares her experience from previous roles, designing and surveying buildings to analysing sub-meter data as part of her current role as a Consulting Engineer in the ETS Technical Energy Centre

Introduction

Metering and monitoring solutions are vital for enabling data-driven energy efficiency.  Sub-metering can provide the necessary insight to identify areas where energy consumption can be reduced.  However, when exploring sub-metering options, you need to consider the following factors in order to find an appropriate solution for your building:

Location, location, location

The position and location of your sub-meters will have a significant impact on the energy data collected.  Sub-metering adds a level of granularity that, combined with BMS information, can enable greater savings.  Before deciding on where to install your sub-meters, decide what you want to achieve and prioritise areas where saving potential has been identified.

Avoid putting meters on very large circuits as the data will not be granular enough to find the savings.  If you are new to sub-metering, it may be best to start with a small number of meters and use these intensely to see if they are achieving the desired results before expanding further.  In some circumstances, temporary metering may be suitable – particularly to quantify savings from specific trials.

Assess the opportunities to install gas, water, heat and coolth sub-meters rather than just electricity.  Also, consider if you would like to recharge any tenants on energy use. All communal heating should be covered by the Heat Network Regulations.

Quality over quantity

It is crucial that you fit good meters which give accurate readings.  Meters are notorious for questionable accuracy, which can be a result of set up or equipment. However, in recent years this has improved and now with the Metering Instruments Directive (MID) there is a list of approved meters.  If your existing meters are old, consider re-commissioning these.

Data communication infrastructure

The route by which data is transferred from meter to desktop is often overlooked.  An effective infrastructure will not only collect meter data, but also store and send it where you need it to go.  This can be done many different ways – consider all available options and make an informed decision regarding the most appropriate method.

Data visualisation, analysis and reporting strategy

Combining your energy data with advanced analytics can provide a deep insight into where opportunities exist to produce greater energy saving opportunities.

Consider what energy data you would like to have visibility of and what needs to be reported on. Then determine how you will turn all that data into savings; this is where analytics plays a vital role to producing savings.  Without understanding building asset performance and comparing predictive models against actuals, it is difficult to identify performance issues.

At ETS, we collect a register of the equipment on each meter and we provide recommendations on actions to take.  As seasons change, we also look at the energy use versus our calculations on what it should be based on the outside temperatures.  We then use this data and translate it into actions to reduce energy consumption.

Allow for maintenance of the system

To stop energy waste creeping back in, it is important to plan and budget for ongoing data visualisation, analysis and reporting.  In doing so, it is possible to find further savings and spot failed meters, or communications dropouts.  It is  recommended that users take annual readings of the meters (photos which include the meter serial number) and check against the data collected.

Future proofing should also be considered – what is the lifetime of the components of the metering infrastructure? If one element fails, make sure it will not cause the entire system to become redundant.  In addition, users should review the system support – can you get spare parts, licensing cost, will others know how to operate it?

Conclusion

Sub-metering identifies energy savings and opportunities to reduce capital expenditure if delivered and managed effectively.  The above touches on just a few key points when introducing sub-metering into a building. The key to success is knowing how to convert all that energy data into operational changes which can reduce energy waste, and this is where ETS’ experienced professionals can help.

If you would like to learn more about sub-metering and how our Technical Energy Centre can support your business reduce energy consumption, call us on 0117 379 0850 or email us at enquiries@energy-ts.com.

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