Understanding billing information
Understanding the energy consumption (electricity or gas) is a key task in energy management and many companies do not understand how to read their bill or fail to do so. Simply knowing how to read energy bills can save money by revealing areas for potential cost reduction.
Actions to take are:
- Learn how to read the energy bills. Contact the supplier if in doubt about any elements of the bill.
- Read and check the energy bills every month. Bills are not always correct and often contain errors.
- Record energy billing data in a spreadsheet every month.
- Cross-check the energy billing data with manual reading of the relevant meters.
- Make the person responsible for energy use (generally the Production Manager) responsible for signing off the energy bills each month.
Energy costs are often in the region of 8% of production costs and most companies do not spend enough time looking at the bills.
Available capacity and maximum demand
The Available Capacity is the amount of power that a site is allowed to draw from the supply network (in kVA). This is a set amount and is the limit of power that can be drawn without penalty charges being applied. The Maximum Demand is the actual monthly maximum power drawn from the network. If the Available Capacity is too high there will be high fixed monthly charges and if the Available Capacity is too low there will be penalty charges. Setting the correct Available Capacity is a strategic decision for management.
Power factor correction
The power factor (or cos H) is the ratio of ‘useful power’ to ‘apparent power’. A low power factor increases losses and improving the power factor with Power Factor Correction (PFC) equipment will reduce the maximum demand (in kW) and allow reductions in the Available Capacity.
Interval data
Most sites will have a recording meter and ½-hour data should be available from the supplier. This is a vital tool and simple plots of energy use versus time will reveal abnormal events and allow these to be investigated.
Energy mapping
An ‘energy map’ of a site is easily prepared and will show where most of the energy is being used at a site. This is often not where it is expected to be! The ‘energy map’ can be used to target efforts to the most rewarding areas and to decide on sub-metering arrangements.
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