It is estimated that commercial buildings currently account for about 10 per cent of Australia’s greenhouse gas emissions – most of which can be attributed to electricity consumption.
This figure has in part spurred the Federal Legislation for the Commercial Building Disclosure (CBD) scheme that came into effect on 1 November 2011.
All sellers or lessors of office space of more than 2,000 sq metres are now required to obtain and disclose an up to date energy efficiency rating, and building owners must obtain and register a Building Energy Efficiency Certificate (BEEC) energy efficiency star rating for the building.
The legislation will have an impact on engineers involved in the construction or redevelopment of large buildings. Now the CBD has been fully implemented, building owners have an imperative to understand their energy consumption and make information publicly accessible on the Building Energy Efficiency Register, and this means it is critical for engineers to understand building energy as well.
Utility costs can exceed 30 per cent of a building’s overall operating expenses, so knowing when, where and how the building (or its occupants) consumes energy is vital – yet many organisations do not take the time to track and monitor their energy use.
How to make sustainable improvements
Most improvements require periodic action in order to continue delivering a benefit. This can include awareness programs, lighting schedules, economisers, automated flushers, and many other activities that require attention and ongoing maintenance after the initial project completion.
Unfortunately, these ‘active’ improvements can be easily derailed by inattention: they can be stopped, turned off, bypassed, corroded, or simply forgotten. All benefit gained is then lost, and the result can be worse performance than if no attempt had been made in the first place.
Any energy management plan needs to go beyond the initial planning and implementation stage and include a long-term strategy for monitoring and sustaining the improvements.
Valuable information and actionable measures
Successful energy management relies on having actionable measures based on real information. But top-level energy metrics are the culmination of daily operations and many decisions made by people, processes, and technology. By the time a top-level issue is recognised, it can already be costly.
It is important to consider what strategies deliver the information to act before a problem develops. In practice, a combination of methods will produce the information to assess and control an active improvement without becoming overly expensive.
As long as the measurements are taken on a regular basis, they will show trends over time, which can be periodically reviewed to determine if the improvement is performing as intended. The measurement method that is selected depends on the level of information required.
Measurement methods take the following three general forms:
• Comparison
• Indirect measurement
• Direct measurement
Comparison
Comparison methods compare the current measurement with a previous period. For building environment measurements, complexities such as the weather, changing operational hours, and building uses may cause discrepancies in data comparison, and these factors make it difficult to use this method.
There are services and software available that model the building and account for these complexities, as the model must be kept accurate in order to be effective.
Bill comparison is simply comparing the current bill with the previous month’s or year’s bill. This method will indicate how a program is performing, but doesn’t usually deliver information about which individual measures are working. It shows overall performance of large projects or those with interrelated improvements; however, it won’t show what other effects are occurring.
Comparison methods, therefore, have a number of drawbacks compared with other forms of measurement due to the variable inputs that cannot be compared or evaluated.
Indirect measurement
Many measures can be taken indirectly, based on assumptions. Impractical or expensive measurements, cost or time constraints, and unknown conditions can contribute to the need to take this approach.
Indirect measurement is effective when any assumptions and measurements for a performance metric have little impact on the metric. Using an LED exit lights as an example, the consumption is the total wattage of all the lamps multiplied by how many hours they are turned on.
In this case, the only measurement needed is total current (amperage), because voltage can be assumed unchanged. If the amperage is higher than it was right after removing lamps, more lights were added or the wrong lamps were used.
Control systems are capable of logging measurements over time. This requires that the device is wired to, or somehow controlled by, the control system. The system logs a time-stamped measurement, which becomes available on one or more system reports.
For example, we might need to determine if a scheduling strategy is still in effect. A look at logged amperage readings over time or the on/off events could give insight as to if the scheduling strategy remains in effect.
Looking at events reported within a control system is also effective for devices that automatically respond to an event. If an access-control system logs room occupancy, then runtime for the lights and possibly exhaust fans is available if they have been turned on because the room is occupied.
Direct measurement
Direct measures show the performance directly without assumption. If the performance requirement in a critical room is to be 20°C +/- 1°C, that can be inexpensively measured and reported.
There are a wide variety of manual and automated sensors for these measurements and a host of systems to record the data produced by them. Measurements can also be captured without automation, as a part of regular maintenance.
Installing a power meter on a sub-circuit or component of a system gives a direct measure of that system’s performance.
Power meters are devices typically installed at various points within a facility’s power distribution system. The role of power meters is simply to record how much electricity is used in a circuit, which can provide an engineer critical data about the areas within a facility that need to be addressed.
Power monitoring is also effective because, in addition to metering electricity usage, these devices can also measure power quality. Poor power quality, or power that’s rife with voltage sags and swells, can have a negative effect on facility components and contribute to substandard performance and unplanned downtime.
Energy management software converts the raw consumption data from power meters and monitoring system into historical data that can be studied to identify areas that require attention.
Sub-meters can isolate a specific area to show if a behaviour program is beneficial and should continue. Where the expected change is less than 10 per cent in each specific area, comparing bills will not be accurate. Variations in the month-to-month consumptions, billing periods, and estimated bills make it impractical for use.
The design and installation of sub metering products when executing a construction or redevelopment project will therefore help the facility or building manager to measure energy usage and comply with regulation and work to reduce consumption over time.
Most improvements require periodic action in order to continue delivering a benefit.
Information you can act on
Buildings are dynamic entities, with constantly changing needs and occupancy. One-time energy audits show only a snapshot of energy use, and monthly utility bills only act as a “rear-view mirror.” Busy operations staff may not have the time, tools, or training to analyse monthly/annual energy use and investigate or troubleshoot incidents, much less compile data into an easy-to-read format to share with business leaders.
Because of the complexities of energy use and its large economic impact, a growing number of firms are turning to remote energy monitoring to provide the technology and know-how to guide, measure, and help manage energy costs.
Using a web-based system, remote energy monitoring automatically collects energy consumption data via smart meters, data loggers, the BMS, and network controllers, or directly from an organisation’s utility provider.
Information is then compiled, organised, and provided in a concise format to show the building’s energy reporting, alarming, and monitoring, as well utility analysis for electricity, gas, heat, steam, oil.
Monitoring can provide up-to-date information on energy use and carbon emissions so companies can identify energy conservation measures, adjust usage quickly, and reallocate savings where needed.
Energy engineers can monitor a building’s energy efficiency and actively look for opportunities to further energy-saving opportunities. In addition, energy alarms can be investigated and long-term trends analysed to help sustain reduced energy consumption efforts.
What does best practice look like?
Schneider Electric has a four step process to achieving the optimal energy management system. This involves measuring and analysing energy use, fixing the basics by deploying efficient devices, automating and optimising performance and embracing a continuous program of monitoring and improving.
The fourth step uses this information as a tool to help change human behavior, making energy management a part of the organisational culture. Those that have followed this four-step process have found they are able to ‘do more with less’ while at the same time achieve significant energy savings.
Four step process to understand consumption and identify waste
1. Measure energy use
Before doing anything, it’s critically important to establish an energy usage baseline because it can suggest the most effective course of action. Additionally, without a baseline, there will be no way to know later whether energy efficiency measures identified as part of a strategic energy management plan are working.
Thus, the first step entails collecting data for major energy consuming applications (e.g. lighting) and analysing the impact of those applications on total consumption. The most effective methods of accomplishing this is through an energy audit and metering.
2. Fix the basics
When they realise that building-wide energy usage requires attention, some facility managers elect to address the easiest fixes first. This can include installing more energy-efficient lighting fixtures and luminaires, increasing insulation, or deploying power factor correction devices.
While these passive energy efficiency tactics can translate into substantial savings, continuous energy improvement over the lifecycle of the facility and changing conditions should be the ultimate goal, which is best facilitated through automation and regulation.
3. Automate where appropriate
There are automation options that create energy and cost savings that are more substantial than passive measures. Lighting control systems, for example, can automatically turn interior and exterior building lights on and off based on a pre-set schedule, instead of relying on personnel to remember.
Motors are most crucial components in the buildings. They drive everything such as pumps and fans for the facility’s water and HVAC systems. Automation technologies can adjust motor speed and reduce energy consumption, which can translate into significant savings.
4. Monitor and control
A strategic energy management plan helps ensure energy and cost savings don’t erode over time. Power meter installations, monitoring services, energy efficiency analysis and energy bill verification can all help achieve this, but one of the most effective ways is through Struxureware Energy Operations Online.
This is a tool that pulls data in real-time from each metering device, uploads to a centrally hosted online portal and delivers business intelligence to company stakeholders in addition to the facility manager.
Embracing an lifecycle approach to energy management
Real-time analysis, information gathering and tested, validated and documented system architectures are critical to streamline processes.
As the need to achieve greater efficiencies across all of industry rises and pressures to reduce energy consumption become greater, the ability to access real-time contextual information to make business decisions is increasingly important. Automation as part of a wider energy management plan should be a key driver to achieve these efficiencies.
[Samuel Coupel is Product Manager, Energy Management & Power Quality, Schneider Electric Australia.]