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Measuring up for energy efficiency

15 July 2013

It’s often said something you can’t measure is something you can’t control, but rarely has this been truer than in the case of energy usage. With this in mind, Richard Molloy of Eaton, examines some of the ways in which energy usage can be monitored and controlled effectively in commercial and domestic situations

For commercial users of energy, Part L2 of the Building Regulations has come as a big wake-up call, since it requires that electrical loads on distribution boards rated at 50kW or over must be separately metered.

The intent behind Part L2 can’t be faulted – it is simply to provide energy users with the basic information they need to work out where they are spending money and racking up their carbon footprint. Meeting the requirements of Part L2 can, however, be a little more problematic.

In particular, the majority of existing distribution boards – and many new ones – have no provision for separately measuring the energy used by individual loads or groups of loads (sub-load metering). And, in the past, adding this provision has often been inconvenient and costly.

However, sub-load metering packs that address this problem are now becoming available. These typically comprise a multifunction electronic meter and its associated current transformers, all mounted in a robust steel enclosure and ready wired to terminals so that installation is fast and easy.

But metering itself is only part of the solution. Who, these days, is going to take the trouble to manually check and record meter readings? Even with the best of intentions, this is the sort of task that slips to the bottom of the pile and never gets done. The answer is automatic collection of data from the sub-metering systems, and the meters used in the best metering packs make full provision for this by providing, for example, Modbus outputs.

These meters can interface with an energy management system that not only logs historical data, but also provides details of instantaneous energy usage, either on demand or continuously.

An effective management system will also support data analysis to allow rapid identification of trends and easy comparison of actual data against benchmarks. Automatically generated reports containing key information will also be featured and, provided that these are well designed and formatted, they are an invaluable guide for implementing effective energy saving measures.

This approach is all well and good for the commercial sector, but what about domestic users of energy? Devices are now readily available that allow overall energy usage to be transmitted to a convenient display, rather than hidden in the meter cupboard, and there are other devices that can be used to check the energy usage of individual appliances. The truth is, however, that for all but the most dedicated of homeowners, the novelty of these devices soon wears off and their readings are ignored.

What is needed in homes, therefore, is an energy management system that measures prevailing conditions and optimises energy usage without depending on input from the homeowner. Once again, systems of this type are now becoming available. Typically they monitor factors like the prevailing wind speed, the direction and intensity of the sunlight, the outside temperature, the time of day and even the day of the week.

Based on this information, these intelligent home energy management systems can control heating, lighting, air conditioning and even ventilation to ensure that comfortable conditions are maintained throughout the home with the minimum usage of energy. As would be expected, provision is also made for manual input, so that the occupants of the house can fine tune lighting levels and temperatures to match their immediate requirements.

Once, systems like this were difficult and costly to install because they required extensive wiring. As a result, wireless systems were developed. But initially these had a reputation for being unreliable, largely because of the limited range of the wireless signals.

The latest systems address this issue by using wireless mesh technology, where every device, in effect, acts as a wireless repeater that can communicate with every other device. These systems combine the reliability of a cabled installation with the convenience and economy of wireless operations.

Today, reducing energy usage is a concern for everyone, and the key to success is, without doubt, measuring what is happening and taking control. Fortunately, as we have seen, the products and systems needed to do this in both commercial and domestic environments are available right now from environmentally aware suppliers like Eaton’s Electrical Sector.

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