Measuring your energy usage to diagnose where to make savings

John Mitchell explains how plants should measure their energy usage to find the best energy saving opportunities 

According to the Carbon Trust, cash savings of up to 20% can be achieved through energy efficiency measures such as installing variable-speed drives (VSD) for fans, pumps, and other motor driven systems. But, a one size fits all approach to energy savings just won’t do. 

The ISO 50001 standard requires organisations to establish, implement, maintain and improve an energy management system. 

To make energy savings, a plant manager must first understand their facility’s energy usage. It sounds obvious, but in reality, achieving energy control and crucial ongoing energy savings requires a strategised approach. The first step is to measure your energy usage. 

Many modern distribution and energy management systems already incorporate energy monitoring and logging facilities. 

However, they may only have a limited amount of memory and are unable to store results over an extended period. In addition, many integrated monitors only store summarised data that do not provide the level of detail needed for effective energy optimisation.

Portable power and energy loggers (PELs) provide a convenient and cost-effective alternative, with far superior capabilities. These PELs, from Chauvin Arnoux for example, can be installed in several different locations, with data from different processes or equipment available on a single screen. 

A real benefit of these modern devices is that equipment doesn’t need to be turned off and isolated during the installation process. 

The next step is carrying out an energy audit. The data from the PEL will show where the most energy is being used in your plant and consequently where the most potential for energy savings can be found. 

The results from this report will inform the type of improvements to implement and crucially where they should be implemented.

Energy saving opportunities can fall into two broad categories, those that relate to the workplace environment and technical aspects of the electricity supply. 

For example, a plant could improve the efficiency of the workplace environment by cutting down on unnecessary out-of-hours usage by switching to LED lighting with occupancy sensors. 

On the other hand, an energy audit may find that a motor is consuming a high amount of wattless or useless power. In this instance, power factor correction would need to be installed to reduce this wastage, without compromising the performance of the equipment.

It’s one thing implementing energy savings, but it’s also important to continually monitor your system to ensure you’re getting ongoing energy improvements. 

Plants should also formulate a metering plan to measure and analyse energy usage over an extended period of time. This will assess whether the chosen energy efficiency measures have been effective or whether further improvements can be made. 

Plants may choose to implement energy efficiency schemes for a range of reasons. While there are several universal energy saving fixes, it’s important that facilities use a targeted approach, which accurately monitors their systems to achieve the most effective energy and cost saving potential.

John Mitchell is global sales & marketing director at supply, installation and repair specialist CP Automation.