There are many opportunities to reduce energy costs through the use of energy metering, monitoring and control.
For information on the main components of an energy management technology system and the benefits of metering and monitoring, see Technology background – Energy metering, monitoring and control.
Optimise the use of existing metering systems
One of the biggest opportunities with existing energy metering (including utility billing meters and local metering) and management systems is ensuring that the energy consumption, trends and key performance indicator data is received by the people who can influence energy efficiency. Automating the communication of this data ensures visibility, and can facilitate presentation in a suitable form.
To be effective, the information must be clear and include analyses, rather than forcing recipients to conduct their own analyses to make sense of the data. To save time, analyses can be automated where possible.
The first step towards making best use of existing metering systems is to list those systems. Compiling this list will probably entail liaising with staff across the organisation, including:
- accounts payable (utility billing meters)
- plant operators (metering incorporated in production machines and supervisory control and data acquisition (SCADA) systems)
- maintenance staff (sub-meters such as those on distributed switchboards)
- utilities staff (boiler house steam or feedwater meters, compressed air meters).
Apart from energy meters, there are likely to be other meters and sensors which can aid in understanding energy use, such as ammeters, water supply and wastewater meters, raw material metering and finished product sensors and equipment hours-run meters. While compiling the list of meters and metering systems, determine whether these meters are read and where the readings are stored.
Analysis which is typically useful includes:
- average daily energy consumption
- energy KPIs, such as energy use per unit of production or value added, e.g. per part, per km, per tonne.
This process can also highlight gaps in existing monitoring and the information needs of operators and managers, which can be taken into account when upgrading systems.
Some examples of opportunities in this area are outlined below.
Use smart billing meters
Smart billing meters have both logging and communication functions. The logging function records the amount of electricity consumed in every 15, 30 or 60 minute period, and this data is stored in the meter for at least a month. The communication function allows the data to be sent from the meter daily. Although smart meters are installed for billing and reconciliation between retailers and their suppliers, the data can be accessed by energy users and is a very powerful tool for analysing energy usage patterns, and for informing staff.
Smart meter data can be obtained through energy retailers or energy management specialists. The data will usually be supplied once free of charge, while ongoing energy monitoring and management may attract charges. The meter data will normally be supplied in a spreadsheet or CSV file to enable analysis.
Energy waste and opportunities could be identified by considering issues such as:
- how the rate of energy use when the site or facility is open or in production compares with the rate at other times
- whether the year-to-date average daily energy consumption is increasing or decreasing
- whether the energy use KPI is improving or deteriorating
- whether there is variation in the rates of energy consumption on different working days, and if differences can be explained by different production rates or weather conditions
- whether there is variation in the rate of energy consumption during different shut-down periods, and if this can be explained by the shut-down procedures used.
Some additional services which add value to the raw data are available through:
- energy retailers, who use these services to entice customers
- third-party independent monitoring services, who are able to provide a consistent interface which will work with electricity and gas usage, and across multiple suppliers—so history is retained if changing suppliers, and a system can be used across multiple sites with different retailers.
Value added services can include:
- automatically receiving data from the metering provider, then importing the data into a database once checked
- providing a web interface for data accessibility
- providing standardised charts and reports for easier analysis
- automatic email reports for the early detection of poor performance and sudden increases in energy use
- automatically collecting data on variables which may influence energy use (e.g. production volume, ambient temperature) and correlating with energy data
- calculating ‘virtual meters’, e.g. combining two meters, electricity use per tonne of product, or carbon dioxide from all electricity and natural gas used on site.
Figure 1 and Figure 2 show examples of charting interval energy meter data.
Figure 1. Electricity time of use data from electricity smart meter, presented as a 7 x 1 day chart
Source: Genesis Now (2012)
Figure 2. Electricity time of use data from electricity smart meter, presented as month and year-to-date chart
Source: Genesis Now (2012)
- Natural Resources Canada (2003) Energy Management Information Systems: Achieving Improved Energy Efficiency (Opens in a new window) PDF 1.1 MB ↩
Utilise installed meters better
Data gathered from existing meters can be better used to assist in understanding energy consumption and identifying efficiency opportunities. Valuable information is often available, such as meter readings taken over a long period, which have not been mined for the insights they can provide.
Using multiple energy meters helps to establish a breakdown of energy consumption. If meter readings have not been taken, it may still be possible to establish an average annual consumption if the meter installation date is known. Many energy meters also provide a direct reading of the instantaneous energy flow, or it can be calculated from energy readings.
Types of meters include:
- Ammeters – Ammeters provide an instantaneous reading of the electrical current, which when combined with an estimate of the power factor and voltage, give an approximate instantaneous power figure. Many ammeters also have an indicator of the maximum current since the indicator was manually reset.
- Hours-run meters – These record the total time that an electrical load has been energised, which is useful when estimating annual electrical energy consumption for that load, especially for constant loads.
- Supervisory control and data acquisition systems – SCADA systems provide production quantity data and product mix data, which when combined with energy consumption data can be used to produce XY plots or multiple regression analyses. This builds understanding of how energy is used, and aids opportunity identification.
Variables likely to influence energy use should also be considered, e.g. weather, quality of raw materials, production speed, flow rates and temperatures. This includes how data on these variables would be collected, and if additional data is needed to calculate indicators.
- Department of Resources, Energy and Tourism (2011) Energy Efficiency Opportunities Assessment Handbook ↩
- Department of Resources, Energy and Tourism (2013) Energy Efficiency Opportunities Energy Savings Measurement Guide ↩
Utilise on-board equipment energy metering capability
Many larger units of equipment have an on-board electricity metering capability which can be tapped into. This applies to devices such as chillers, air compressors, large circuit-breakers and variable speed drives. The in-built meters often have a high level of interface connectivity. This means they can transmit multiple parameters over a single cable, enabling a range of energy parameters to be communicated to the energy metering and monitoring system.
For more information
Optimise the use of existing control systems
Energy savings can usually be achieved by optimising the operation of existing control systems. This makes the best use of the capital already invested in those systems.
The settings and control actions of older stand-alone controllers could usually be viewed by looking at gauges and indicator lights on a switchboard. Modern control system settings and control actions are usually only visible through a user interface. Interrogation or inference from energy consumption profiles may be required to determine what the system is doing.
Actions to optimise existing control systems are outlined below.
Monitor the control system
The control system should be monitored to ensure it is functioning as intended. As these systems are automated and often the responsibility of an external contractor, there is the risk that equipment can operate when not required, which can go undetected for long periods. Determining whether this is occurring will be easier if the conditions and operating states are logged by the control system for later examination.
Energy metering data can be used to verify that the control systems are performing as intended. Virtual meters, that is meters created in software, should be used where possible to check veracity of energy metering data.
Log and analyse data
Program the system to regularly store input and output parameters (e.g. every five minutes, or other time period which matches the interval meter data frequency). Even if there are no immediate plans to analyse the data, it will be available when needed. A longer data collection period will capture a range of operating conditions and reveal trends. Where meters are connected to the energy management information system, logging should include energy-use data.
Analyse the relationship between the measurements of energy consumption and the independent variables which are expected to influence energy use.
Compare the logged energy consumption with the theoretical energy requirements under the conditions revealed by the measured values of the independent variables. This provides useful benchmarking against ideal performance.
Control maximum demand
If the energy control system monitors electricity or gas demand, and the retail or network tariff includes a demand cost component, investigate whether there are loads which can be controlled to limit the demand to a target figure. Methods of control can include duty cycling, load modulation or limiting the amount of energy-using equipment that operates simultaneously. This control may also include smart load-shifting and shed/restore load techniques.
Also ensure that the control system’s demand-monitoring periods are synchronised with the billing meter monitoring periods. The billing meter may provide a synchronisation signal or pulse.
The actual maximum demand reached each month, and the contract demand should be shown on each energy invoice. The contract demand is the rate of energy use which is used to calculate the monthly demand charge. It is typically highest rate of energy use, either in the last year (12 month rolling maximum) or ever recorded for the account.
For more information, see Procuring and managing energy.
Review use of control systems and programs
There are a number of steps that can be taken to maintain and review control systems and programs, including:
- recommission existing energy control systems to ensure that sensors, actuators and relays that are controlled by the system function correctly, and correct operation under the range of conditions are as expected
- update control programs in response to changing circumstances
- regularly review the program requirements and settings in the site asset and maintenance register and make frequent back-ups
- consider the controllable loads and the circumstances under which they should (or should not) operate – the degree of control sophistication can be increased over time to progressively improve energy efficiency
- consider whether the factory supervisory control and data acquisition (SCADA) system, which currently controls production machines, can also be used to turn off ancillary equipment—such as conveyors or exhaust fans—when the production machine is turned off.
Upgrade or replace energy metering, monitoring and control systems
Further opportunities can also exist in upgrading, replacing or installing new systems. These opportunities can include installing additional meters, upgrading control systems through increasing loads, and improving staff access to the control systems and energy data for staff.
Some examples of opportunities in this area are outlined below.
Install additional energy meters
In order to effectively manage energy, just controlling energy use is not sufficient; energy metering and monitoring of significant equipment is also required.
This level of sub-metering does not have to be achieved in one go. Sub-meters could be installed progressively in response to questions raised by data analysis and modelling, and the need to evaluate specific opportunities.
Specify energy meters that can be used to communicate with the energy management information system using a high-level interface rather than a pulse via a contact closure or transistor switch. Also ensure meters have a proven and appropriate accuracy and good local technical support.
The cost of energy meters is often low enough to make permanent installation preferable to temporary installation, considering the additional cost of uninstalling the meters and the added benefit of ongoing data from permanent metering.
Install new energy control systems
When specifying a new energy management information system, or upgrading an existing system, consider the following features:
- Compatibility – The system should be able to communicate with existing sensors and devices, so the communications protocol specified will depend on the most prevalent protocol among the installed devices. Also ensure that the control protocol chosen has multiple equipment suppliers to avoid being locked into one supplier’s products. If expanding into relatively inaccessible areas, mesh radio systems may allow this to be cost-effectively implemented with common wireless protocols.
- Commissioning – Commissioning means ensuring that a new energy metering, monitoring and control system performs in accordance with the intent, design and specified functions. This includes witnessing the operation in all situations and expected ranges of inputs, and required control actions. Commissioning should occur when a system is first installed, using a structured approach. Commissioning might take up to a year depending on the need to check the system under different weather and operating conditions. Some components may require ongoing checking to ensure initial performance levels are retained, which may include scheduled calibration of sensors. Any subsequent changes should be documented.
- Staff Training – The flexibility and reporting potential of an energy metering, monitoring and control system will not be realised if staff are unable to operate the system effectively. Training should be provided as part of the system installation, and in response to system or staff changes.
- Staff Access – Where appropriate, ensure staff have access to the system to make basic adjustments to control settings and logic. Also, specify the ability to interface the energy system to the internet, so that:
– the system can be accessed and updated by staff members who are offsite
– reports can be viewed by or automatically sent to various stakeholders
– the system can accept data or inputs from online services such as weather forecasts and purchasing records.
The pace of energy management technology systems development is rapidly increasing as:
- computer technologies evolve
- controls, equipment and components become cheaper
- focus on energy management and emissions reduction intensifies
- demand for skilled staff increases.
Continuing and future developments include:
- data collection, intelligent control and communication capabilities being increasingly devolved to intelligent energy-using equipment, appliances, and other distributed intelligent devices
- increased communication among energy-using devices, meters, sensors and controllers, and sharing of data among systems
- more open-source data formats and communication protocols
- movement of electronic data and applications to the internet (cloud storage)
- real-time energy efficiency benchmarking and model validation and calibration.
These developments and trends, combined with increasing energy prices and network charges, and the focus on greenhouse gas emissions, will increase the already rapid uptake of energy metering, monitoring and control systems.