Sub-metering is the installation of metering devices to measure energy consumption at specific points within a building. It is an effective way to understand energy consumption, recognise power quality issues, identify waste within a facility, and measure and track key performance indicators, such as watts per square metre, occupancy, total tenant load, common area costs and carbon footprint.
Before doing anything, it’s critical to establish an energy usage baseline to help identify the most effective course of action for a building. Additionally, without a baseline, there is no way to know later on whether energy efficiency measures identified as part of a strategic energy management plan are working. The first step involves collecting data for major energy consuming applications (for example, lighting, lifts and air-conditioning) and analysing the impact of these applications on total consumption. One of the most effective methods of accomplishing this is through power metering and monitoring.
Power meters are devices installed at various points within a facility’s power distribution system. The role of power meters is to record how much electricity is used in a circuit and thereby provide critical data about the areas within a facility that need to be addressed. These devices can also measure power quality. Poor power quality, or power that is 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.
Once these areas have been identified, the easiest fixes should be made first, such as installing more energy efficient lighting fixtures and luminaires. While these passive energy efficiency tactics can translate into substantial savings, continuous energy improvement over the life cycle of the facility and changing conditions should be the ultimate goal.
Automation options that create energy and cost savings 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.