ISO 50001 EnMS – Using Energy Metering to Set Benchmarks and Measure KPIs

Efficient energy metering and management is a key concern that continues to challenge companies across the world. Rising energy costs have forced them to make better use of building automation, metering, data acquisition and processing systems to track consumption, wastage and demand at a granular level and optimise energy utilisation. Many organisations are now exploring new alternatives such as distributed energy resources (DERs) to address their growing energy needs.

ISO 50001 is an international standard that offers a comprehensive framework to setup, apply maintain and enhance the effectiveness of Energy Management Systems (EnMSs) on a continuous basis. Based on the Deming Cycle, the framework requires organisations to carefully plan and strategise their energy management efforts before implementing them and improving energy efficiency, until energy targets are achieved.

Energy Metering

The objectives or targets of an energy management initiative must first be finalised before embarking on action. It is important to decide what an organisation or utility service provider wishes to accomplish using energy data from metering systems and then address the question of how best to achieve the intended results.

The adoption of ISO 50001 and compliance requires companies to:

  • Define objectives and targets
  • Detail action plan
  • Identify energy benchmarks/baseline
  • Establish Key Performance Indicators (KPIs)
  • Formulate a framework to monitor, measure, and analyse energy data
  • Conduct periodic reviews to improve performance

Benchmarks and KPIs are two critical aspects that determine the success of energy management initiatives. Knowing what to measure and compare is as important as knowing the goal the company has set out to achieve.

Energy benchmarks serve as a standard against which energy efficiency of a given site/location is compared. These can either be energy data from the same site (usually historical) or other external sites or locations with similar functions and sizes.

Key performance indicators, on the other hand, are specific parameters that help measure energy efficiency. These are directly mapped to energy data collected by the different metering systems on site. KPIs usually are site-specific and vary based on the size and function of the location. Defining the right KPIs, therefore, is important to get a clear picture of energy demand, supply and consumption at a given site.

For example, data centres typically will be interested in tracking power usage effectiveness, cooling efficiency, UPS efficiency and use, and energy efficiency of servers. Monitoring the density of light, efficiencies of fans, heating/cooling systems, pumps, etc. seem more relevant in residential/office buildings.

Determining the Right Benchmarks and KPIs

Facility managers are usually adept at determining site-specific KPIs. However, for those who need assistance, answering a few simple questions and working forward from actual energy consumption data often helps identify relevant KPIs without much difficulty. This can be done in just a few steps.

  • Determine Significant Energy Uses (SEUs)
  • Spot factors that influence energy use
  • Note consumption metrics and decide on what can be metered
  • Establish energy KPIs for each SEU based on energy drivers
  • Decide on benchmarks or references (internal and external) to compare energy performance
  • Define realistic goals to achieve

Working forward from energy consumption or SEUs at the granular level, the goal-setting exercise for energy management becomes even more meaningful and relevant. Mulling on a few significant queries at each step of the process has been observed to prove valuable:

  1. What are the site-specific general and significant energy uses?
    Significant energy uses such as HVACs, gas-based heaters/boilers, lighting, heavy equipment/machinery, production plants/lines are key points that need close monitoring and control for effective energy management.
  2. What factors drive or influence energy use?
    Energy consumption tends to vary based on several factors such as floor area or expanse of the site, occupancy or use of site, the number of machines or production units in a manufacturing facility, external weather conditions, etc.
  3. How much energy does each of factors demand?
    Is it possible to control them? If at all, then how?
    Is it possible/necessary to meter energy consumption?
    Meters for lighting (kWhs), gas consumption (MMBtu), production lines and HVAC use (MWhs) are available to individually measure each SEU.
  4. What performance indicators to monitor to track each SEU?
    Energy used or energy costs per unit of production is widely used in manufacturing facilities.
    Energy used for lighting per unit of occupancy.
    Total energy consumption for floor area.
    HVAC energy/degree days (based on external weather conditions).
  5. Are there any guidelines or recommended best practices for energy management?How are others with similar site size and function implementing energy management?
    Which other locations can serve as benchmarks?
    How has internal energy performance improved over time? What is the internal baseline against which current performance should be compared?

Answers to these and other relevant site-specific queries automatically will pave the way for clear, achievable, and realistic energy efficiency goals to work towards.

Technological advancements now facilitate data-driven decisions, making it easier for decision makers to base their actions on real-time data readily available via the cloud. With energy management goals, KPIs and benchmarks in place, it is possible to map hardware units to automated systems and enterprise software and suitably use the metering infrastructure and sensors to gather and analyse energy data, monitor and control consumption, identify and minimise waste and improve the energy efficiency of a specific site/location. Guided by the ISO 50001 framework, companies will be able to address their specific energy concerns in an effective manner.

For further information contact us on 057 866 2162 or email us here.

Harmonics – Understanding, Measuring and Interpreting Results

From minor control trips right down to compressor and transformer failures, harmonics can have an impact on every type of HVAC equipment. Surprisingly, harmonics is something that quite often can be overlooked.

Harmonic currents and the electrical distribution system

Understanding HarmonicsHarmonic currents flow in a circuit at multiples of the fundamental 60 hertz (Hz) frequency. For example, current flowing in a circuit at 180 Hz is the third harmonic (60 Hz multiplied by 3). These currents are not indicated on multimeters and therefore are usually not detected until unusual control and equipment problems start to happen. Comparing these current readings from an average-responding meter to that of a good quality true-rms meter on the same circuit will help in indicating harmonic issues. An average-responding meter will specify only the 60 Hz current, the true-rms meter can indicate a combination of 60 Hz and harmonic currents.

The production and reflection of these harmonic currents back into the electrical distribution system can cause problems such as:

  • Improper operation of control circuits
  • Faulty shut-downs of electronically controlled chillers and air handler units (AHUs)
  • Overheating of solenoid coils resulting in a replacement being required
  • Overheating of 480 volt transformers (supplying 208Y/120 volt HVAC systems)
  • Overheating of fan and chilled water pump motors

It is now possible for professional technicians and engineers to isolate harmonic issues back to their source and then mitigate their effects by either replacing the problematic item or by installing harmonic filters.

Modern electronic circuits must convert the supplied 60 Hz alternating current (ac) into direct current (dc) since the electronics operate using dc voltage and current. The waveform of the current drawn by these electronic loads reveals that the current waveform does not correspond to the voltage waveform applied. Thus, such electronic loads are referred to as “nonlinear” loads. These nonlinear loads produce the harmonic currents reflected back into the system. Harmonic currents appear across a wide spectrum, but generally diminish as the frequencies get higher and higher. See Figure 1.

Understanding Harmonics-Figure 1

Figure 1. Nonlinear load. Observing one single-phase set of voltage and current sine waves drawn by a variable frequency drive (VFD) readily shows that the current waveform (lower) does not conform at all to the voltage waveform applied. Such nonlinear loads produce harmonic currents that flow into the distribution system.

While different harmonic frequencies produce their own unique effect in a circuit, when combined they can distort the original 60 Hz sine wave. Distorted power at the input point to electronic equipment can create the erroneous trips and alarms that sometimes occur in control circuits. Some harmonic currents will produce excessive heat while other harmonics produce a reverse torque in motors therefore reducing efficiency and overheating motors.

Troubleshooting

Troubleshooting in any circuit means properly identifying the root cause of the problem and then isolating the source. If this routine troubleshooting does not reveal the problem you will have to consider looking for harmonics:

  • Measure with a clamp meter that is capable of indicating total harmonic distortion (THD). THD for voltage should not exceed 5 %. THD for current will run considerably higher.
  • Use a power quality analyzer to further investigate the magnitude and effects of the individual harmonics. Power quality analyzers are available for both singlephase and three-phase circuits. In addition to measuring harmonics, power quality analyzers record other disturbances that can cause malfunction of control circuits. For example, “swells” are increases in voltage above the rated values and can damage equipment. “Dips” are decreases in the applied voltage and will causes spurious shutdowns and false alarms in variable frequency drive (VFD) and programmable logic controller (PLC) circuits.
  • THD and harmonic levels should be measured at the point of common coupling (PCC) – the point at which the nonlinear loads suspected of causing the problem connect to the remainder of the distribution system. Look for THD for voltage approaching 5 % and check for the presence and the levels of different harmonic frequencies. See Figure 2.

Understanding Harmonics - Figure 2

Figure 2. Harmonics. In this power quality analyzer screenshot, the harmonic frequencies appear on the harmonic axis. The percent to which the specific harmonic frequency is a component of the fundamental 60 Hz frequency appears on the vertical axis. The cursor has been placed over the third harmonic frequency, and this third harmonic current appears to represent approximately 25 % of the 60 Hz frequency.

What to do when you find excessive harmonics

If you find excessive harmonics, review each case individually before making a decision on a course of action. You can buy harmonic filters and put them as close as is possible to the equipment that is producing the harmonic currents. You can consult the manufacturer of the equipment or an outside engineering consultant to recommend the most suitable harmonic filter for the problem.

Another alternative is to isolate the problem equipment using an isolation transformer. Relocating either the nonlinear load causing the problem or the affected circuit to another distribution panel may help. For example, if the affected controls are supplied from the same panelboard as the nonlinear load causing the problem, moving the control circuit to another panelboard may help alleviate the problem. Harmonic problems tend to diminish moving farther away from the nonlinear load.

 

Click here for further information on Understanding Harmonics, Troubleshooting and Measuring and Interpreting Harmonic Numbers.

You can also email us for further information or call us on 057 866 2162, we’d be happy to answer any queries you might have.