ACTING ON YOUR ESOS ELECTRICAL ENERGY ASSESSMENT

With the 5th December 2023 deadline for phase 3 compliance to the ESOS Regulations approaching many qualifying organisations will have had the latest assessment of their energy consumption completed. But what now?

The Energy Savings Opportunity Scheme (ESOS) is a mandatory energy assessment and reporting scheme aimed at promoting energy efficiency and reducing greenhouse gas emissions. It was established in July 2014 under the Energy Efficiency Directive of the European Union. By identifying cost-effective energy-saving measures and promoting a reduction in energy consumption, ESOS aims to contribute to overall energy efficiency and environmental sustainability.

To fall under the purview of ESOS a UK business must either employ 250 or more people, or have an annual turnover exceeding £44 million and an annual balance sheet total exceeding £38 million. Under the regulations, qualifying organisations must conduct comprehensive assessments of their energy use and identify energy efficiency opportunities at least once every four years.

The assessments provide valuable insights into a company’s energy performance and serve as a foundation for developing effective energy saving strategies. They include recommendations for energy efficiency improvements and details of actions taken or plans to implement those recommendations.

As part of their assessment, organisations will almost certainly receive a variety of electricity consumption profiles based on their half-hour billing data. These should be assessed to ensure they accurately reflect the working hours and processes that take place in the business, and can be particularly useful for identifying out of hours electricity use during evenings or weekends, for example.

Armed with the necessary electrical power consumption data, the next step is to identify areas or items of issue and put in place corrective measures. After all, while the need to perform an ESOS assessment may be due to a mandatory requirement, the whole point of it is to then use the knowledge gained to make energy efficiency improvements. And with the recent rises in energy costs what business doesn’t want to reduce energy consumption and save money, while supporting the environment at the same time. Studies by the Carbon Trust show savings of up to 20% can be achieved through energy efficiency measures. Out of hours usage accounts for 46% of energy consumption in UK SME’s according to a recent British gas smart meter survey. Office equipment plays a significant role in the energy consumption of a small business, and turning off nonessential equipment at the end of the day can achieve savings of 12%. Office equipment left on standby during Bank Holidays and weekends will cost the average SME up to £6,000 per year. Up to 40% of a building’s electricity use is accounted for by lighting, and installation of occupancy sensors, daylight sensors or photocells, and replacing existing lighting with LED modules, can reduce electricity costs by between 30% and 80%.

Once a business decides to take the plunge to look at their electrical usage, they will need to use a portable energy logger (PEL) like the Chauvin Arnoux PEL103. With it they will be able to accurately monitor power consumption and much more, including the level of harmonics in the systems, load balance and power factor. Furthermore, they will be able to record the results over time giving comprehensive and reliable data about what is contributing to the energy consumption of the business.

Having obtained a PEL the next step is to decide where to install it. This will usually be in a distribution cabinet with the logger set up to monitor the circuits that are of most interest. Typically, these might be lighting, HVAC and possibly computer systems, or to start with, perhaps the energy drawn by the installation as a whole. Some three-phase PELs, including the PEL103, can also be used to monitor three single-phase circuits simultaneously which saves a lot of time.

The PEL should be set to make recordings over a period; a day is good, but a full week is better, as interesting things often happen at weekends. It may also be useful to record information over even longer periods to see seasonal trends.

Once the logged data has been downloaded from the PEL, the first thing to look for is out-of-hours usage. How much energy is the business continuing to use after the workers have gone home in the evening and over the weekend? Some of this usage will be necessary, of course, but a lot isn’t, and armed with reliable information from a portable energy logger the issues can easily be identified and addressed. The solution often being no more costly or complicated than installing a few time switches.

It’s a good idea to measure and log the energy consumed by lighting. Typically, this accounts for around 40% of the energy used in a building so it will repay careful examination. If it looks as if too much is being spent on lighting and all the unnecessary outof-hours usage has been eliminated, it may be time to look at the luminaires. Hopefully they are already low energy, but even so, substantial extra savings can possibly be made by switching to the latest LED types. Depending on the type of luminaire, this may involve no more than changing the bulbs, an exercise that will quickly pay for itself.

A PEL will also give vital information about the power factor of an installation. Poor power factor, and the associated high reactive currents, can cause a variety of issues within an electrical installation. Many network operators apply penalties in the form of a reactive power charge when power factor falls below a certain level, and this may be recorded as a parameter on a half hourly meter.

The good news is that it is possible to ‘correct’ poor power factor and so reduce the amount of reactive power. This correction usually takes the form of capacitors fitted near the main distribution board, but over time these capacitors can decay. It is also often the case that loads change over time without the power factor correction being appropriately resized. As a result, the power factor may be much worse than expected and reactive power may be adding a significant costing to the business.

Computers, LED lighting, variable speed drives and many other types of load found in modern installations generate harmonics, which are currents at multiples of the supply frequency. A PEL will record the size and order (frequency) of these harmonics to determine whether they are likely to be a problem, with the logged information helping define what action to take to mitigate them. www.chauvin-arnoux.co.uk

Harmonics are unlikely to add much directly to the energy bill, but they can cause many other types of costly problems, like overheated neutral conductors, malfunctioning and premature failure of IT equipment, and excessive vibration of motors, so they are well worth investigating.

Assuming the business has a three-phase supply, another step in the preliminary analysis of the PEL data would be to check the load balance. In other words, whether the current drawn is the same for all three phases, and whether it stays that way throughout the whole day and whole week.

Current imbalances can often be caused by large single-phase loads, such as induction furnaces, traction systems, and other inductive machines. The uneven distribution of smaller singlephase loads across a 3-phase system can also cause a current imbalance, often occurring over time as an installation, originally balanced during its construction, has additional circuits and equipment added to it. If the loads are out of balance this could result in peak demand billing by the supplier and reduced performance and efficiency of other items in the installation.

Without doubt the Chauvin Arnoux PEL103 can relatively easily assist businesses in identifying energy inefficiencies, optimising equipment usage, and making informed decisions to improve energy efficiency following an ESOS assessment. And while it’s only been possible to give a few suggestions in this article, the Chauvin Arnoux technical team is at your disposal, and will be happy to help with all your energy monitoring and energy efficiency enquiries.