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Rising power prices and increased government legislation have pushed energy management to the fore, with public and private users implementing an array of measures to cut consumption, bills and carbon emissions. For many organisations this process starts with an energy audit to pinpoint how much power is being used and where and sub-metering has become an established, straight-forward and effective method of doing this.
Advancements in sub-metering technology now allow this process to be carried non-invasively and with wireless reporting of results, which is a massive benefit to many clients.
Sub-metering does exactly what it says on the tin – it measures the amount of electricity (or gas/water) used within premises in a precise manner. This information can be used in a variety of ways, from checking utility bills to carrying out an energy audit or implementing a cost centre charging programme. Not all sub-metering systems are non-invasive and even fewer offer wireless reporting coupled with non-invasive installation, so it’s worth researching the market to ensure the system selected does what’s required of it.
Saving money
The reasons for sub-metering are multitude. We’ve had clients wishing to check their electricity bill, for example one school in Scotland installed a portable energy analyser after receiving a bill for £50,000. The Sinergy analyser revealed that a meter reader was applying a 10x multiplier factor to the wrong meter and the bill was subsequently amended, saving the school thousands of pounds. Other clients simply want to reduce power consumption but are not sure how. A good example is a leisure provider who installed a sub-metering system and discovered its power consumption rocketed after midnight every day. Investigations uncovered cleaners switching on floodlights in order to enjoy a cigarette break!
Sub-metering can also deliver great results for organisations signed up to STOD (Seasonal Time of Day) tariffs. One Sinergy client was on a tariff with no demand charges but a high penal unit charge in winter weekday late afternoon periods. Daily reports detailing electrical usage were required to help the company ameliorate the worst effects of this tariff. A Sinergy sub-metering system allowed the business to measure power usage and the information gathered was shared with managers across the site who not only protected the company’s exposure to the penal rate but also achieved savings amounting to 20% of total units consumed simply by being made aware of actual load profiles.
Measurement techniques
Sub-metering systems can be fixed or portable, with the most popular offering non-invasive monitoring. In practice this means clip-on transducers (CTs) which Marshall-Tufflex Energy Management also offers. Both approaches utilise a precision wound aircored inductor integrally coupled to a hybrid integrator module to provide an AC voltage signal directly proportional to the AC current being measured. Other measurement techniques are available but our research and development has shown this to be the most accurate method.
For many sub-metering installations manual collection of data is more than adequate. However, for a growing number of clients wireless capability is becoming increasingly important, delivering an immediacy and flexibility that allows virtual micro-managing of electricity usage, particularly across geographically dispersed sites or locations with a large number of sub-metered supplies.
Marshall-Tufflex Energy Management’s Sinergy Pulse Plus wireless sub-metering system was launched at NEMEX 2011 and created much interest, with a broad range of public and private sector clients interested in its capabilities. For example, we previously highlighted its suitability for geographically dispersed sites which could be anything from chain store outlets around the country to leisure centres, sports venues, hotels and out-of-town retail outlets that are all part of the same operating groups or under the same management.
In operation, Pulse Plus unit/s would be installed into each location. The GSM-enabled solution has a range covering 10A full scale to 5,000A full scale and, once connected on site with split core CTs in place, begins monitoring power consumption immediately. Data is automatically downloaded via the mobile phone network to a computer as and when required, with data also backed-up and stored in an on-board memory. Automatic energy data collection includes parametric amps, volts, PF, KW and KWH.
Analyse data
Data can be analysed by Sinergy Deltrax5 graphing software or, alternatively, imported into Excel. For multiple channels requiring extensive data manipulation third party software packages are available. Pulse Plus is fast and cost effective to install and, with all connections being plug-in, and the CTs split core, fitting is easy and power supplies do not need to be isolated or cables disconnected. A key advantage of the system is its ability to measure single or three phase loads, with only a single phase voltage connection. It then creates the three phase voltage measurement vectors in a safe, quick and convenient way.
Energy or facilities managers overseeing multi-location retail and leisure sites, for example, can quickly and easily download current power usage figures from any number of sites around the country, comparing consumption at each and working with on-site managers to reduce usage where it is deemed too high. Such close monitoring of electricity demand can also allow detection of equipment malfunction, which may show up as a demand spike.
In an office environment this system makes it far easier to implement cost centre charging schemes, for example measuring the power usage of individual departments or floors within one company and billing accordingly. The wireless system can be set-up to report daily, for example, with a public dashboard showing the power performance of each department. Anecdotal evidence suggests this approach engenders a competitive spirit amongst staff and meaningful power savings follow.
User pay flexibility
Wireless sub-metering also lends itself beautifully to serving ‘user pay’ sites, both domestic and commercial. Take an office block with a number of tenants for example where the building owner/ manager may apportion the overall electricity bill to each tenant according to, for example, rental unit size. This does not take into account the individual power usage of tenants, but by installing a sub-metering system for each rental unit, consumption can be directly apportioned to each user, which is a far fairer and democratic method. Make it a wireless sub-metering solution and the building manager can automatically download consumption figures.
Conclusion
Wireless sub-metering is many things to many people. Commercial/industrial users can utilise it as a strategic tool to monitor and control consumption, identify inefficient areas of operation and easily implement a cost centre charging regime across a large number of sites. For other users it offers the potential of fairer bills, easier meter readings and current consumption data - all in the palm of your hand.
