Minimising the maximum

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Managing energy bills to minimise the maximum.

Understanding and monitoring energy bills can provide facility managers with valuable insights into how a building responds and behaves in different conditions, writes ARIAN BAHRAMSARI.

Electricity bills comprise two main sections. These outline consumption charges and network charges. Although some believe network charges are not negotiable and nothing can be done about them, this is not always the case.

Demand charges

The demand charge is usually reflected in an electricity bill as part of the network charges. It may be an explicit rate per kW/kVA (kilo watts/kilovolt ampere) or a Contracted Maximum Demand (CMD).

The demand charge is normally calculated based on one year rolling maximum measured demand for the building. This means the network will typically reassess the rate every 12 months. If demand increases today, customers won’t see an increase in demand charges until this time next year. In other words, mismanagement of a building’s electricity load can result in a higher rate for a full year. Therefore, it is imperative to monitor the maximum demand and have a plan to minimise it in the building.

Maximum demand management

1) The first step in managing maximum demand is to obtain the building’s load profile. You cannot manage what you cannot measure. Facility managers should investigate their building’s essential loads and find out how their building performs throughout the year. The building’s current maximum demand needs to be considered. In Victoria, CitiPower and Powercor Australia have developed an online tool named myEnergy. This portal allows facility managers to see how a building is performing over time and obtain the maximum demand figure.

2) The next step is to understand the current tariff rates and time-of-use tariffs outlined in electricity bills. Facility managers may consider how the electricity rates change at different times of the day. Generally:

  • Peak period rates are the most expensive and typically run from 3pm to 9pm.
  • Off-peak rates are the lowest and typically run from 10pm to 7am.
  • Shoulder rates sit in between peak and off-peak periods.

It is worth mentioning, buildings with solar panels must have a solar feed-in tariff (FIT) in their electricity bills. Facility managers may get this checked, as some utilities are required to have a FIT form completed before customers are credited for solar generated power.

3) Demand management is all about staggering equipment use. Facility managers can make some simple adjustments to their building’s essential loads to make sure they are spread out over the day. If possible, another strategy is load shifting. This involves shifting appliance use from peak hours to off-peak hours. Let’s take a building’s lighting and irrigation systems as examples. Facility managers may consider a staged lighting schedule throughout the peak times rather than turning all lights on at once, while an irrigation system can be switched off during peak hours and reactivated during off-peak times.

4) Another demand management strategy is to install a real-time early alarm system in the building. These smart monitoring systems can notify facility managers via an email or text message when the building demand is close to its maximum. In these instances, non-essential loads can be switched off for a period of time.

5) On very hot days, limiting temperature controls can alleviate strain on the building’s cooling system. For example, facility managers can choose to limit air-conditioning temperature set points in common areas such as meeting rooms and recreation areas through a building’s management system. By doing this, even if occupants try to change temperature settings cooling units will not go below the set point.

6) Alternating power sources and local generation are other methods that can help manage a building’s maximum demand. Natural gas-fired chillers and pumps and solar water heating can be implemented to reduce the maximum peak energy use. If there is a reserve fuel generator in the building, it can be used to supply a portion of the facility’s needs when electricity demand is hitting the peak.

7) Upgrading old and non-efficient equipment is an effective way to permanently reduce peak hour dependence. Consider installing LED lighting, variable-speed drives and a power factor correction unit.

8) Addressing maximum energy demand with energy storage can also be beneficial. Facility managers may consider energy storage options for their building. Energy storage can enable some services to switch from grid to storage during periods of high demand to offset electricity usage. There are various storage solutions that can be deployed in buildings, such as batteries and thermal storage.

In summary: an effective demand management plan requires facility managers to analyse utility cost correctly and know how to quantify major and minor loads in their building. The end results are cheaper power bills and a more energy efficient building.

Arian Bahramsari is a facility manager at Facility Management Victoria PTY Ltd, based in Docklands, Melbourne.

 

Image: 123RF’s sashkin7 © 123RF.com

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