Welcome to CopperTree’s new Application Series – a collection of articles focused on answering key questions around relevant principles and concepts in our building analytics domain. Our main objective is to offer practical how-to advice, clarifying terminology and highlighting benefits help set the foundation on which you can build actionable workflows.
Is the lack of energy meters – and the high cost of adding them – preventing you and your organization from adopting analytic-driven solutions?
If you answered yes to the question above, you are not alone. According to the Survey on the Enablers and Barriers to EMIS, the “Lack of existing metering in place/cost of adding meters” was the third-largest barrier to success as revealed in the Year 3 Outcomes report by the Smart Energy Analytics Campaign.
This blog provides some insights on how to overcome the lack of energy metering. And even if you have already joined the analytic-driven community, but are now wishing you would have more metering in place, we give practical steps to leverage the array of existing sensors for measurement and control that are most-likely already available through your Building Automation System (BAS).
A three-question framework will guide our discussion, answering the what – to clarify terminology, the why – to understand the benefits, and the how – to put into action.
What is Virtual Metering?
- Virtual metering is the leveraging of existing sensor data to derive other measurements not monitored by physical instrumentation or real sensors. From A Case for Virtual Metering
Based on the same methodology featured in off-the-shelf energy meters, voltage and current measurements are used to internally calculate power and energy following the laws of physics. While this article centers around these principle-based virtual meters, another type using conditional statements are perfect for creating equipment run-time and system performance meters. These decision-based virtual meters will be featured in a separate application blog.
Electrical and thermal energy meters are typically derived from various equipment status indicators and process measurements such as current, speed feedback, temperature and flow. Figure 1 shows a list of built-in electrical consumption formulas ready to configure virtual meters based on available equipment data.
Figure 1. Electrical consumption virtual meters
Why Virtual Metering?
- Because it does not require added monitoring infrastructure, minimizing operational impact while avoiding equipment and installation costs, thus making economic sense.
- Because it enhances data already present, leveraging it with supplemental energy monitoring, thus expanding visibility and bringing additional value.
Figure 2 below highlights the benefit of supplemental energy monitoring. The different coloured stacked bars represent different systems or pieces of equipment serving the office space. While a building-level energy meter would totalize daily energy consumption, virtual metering provides this dis-aggregated view to help identify the highest consumers or pinpoint irregularities in operational patterns.
Figure 2. Monthly view of daily energy distribution using virtual meters.
How to Implement Virtual Metering?
- Determine System Priority – List all systems you would want to tackle first. The criteria is up to you, but typically, these systems have the largest energy footprint, have been problematic in the past, serve high-complaint areas, or are related to a financial study for a potential retrofit project.
- Identify Existing Sensors – Make an inventory of all sensing devices with continuous data accessible through your BAS. These monitoring points are primarily status indicators and process measuring devices. More details below.
- Gather Equipment Data – Collect all pertinent equipment attributes such as motor capacities and pump nominal flow rates, typically obtained from mechanical schedules, O&M manuals, CMMS databases or directly from equipment nameplates.
The above steps provide the basis for the configuration of virtual meters. Getting started with a brief list in step 1 is helpful, especially if you have hundreds of systems in your building. In Figure 3 below four fan coil systems serving an office space have been identified, each with a virtual energy meter configured for the compressor, the electric heater and the fan coil motor.
Figure 3. Virtual meters configured for fan coil units, cooling compressors and electric heaters.
In step 2, make sure your inventory includes status indicators and process measuring devices. While the former group includes amperage readings, speed feedback and auxiliary contacts that confirm equipment operation, the latter one is made up of basic sensors and specialized transducers monitoring temperature and flow, for example. Once equipment data have been obtained in step 3, you would be ready to begin configuring virtual meters. Use Table 1 below to help determine the potential meters that are possible based on a complete set of data in each row. Actual configuration steps would vary depending on your Energy Information System. In Kaizen Energy, the next steps involve selecting the appropriate formulas as shown in Figure 1.
Table 1. Status and sensor data alongside equipment data required to configure virtual meters.
We hope this practical how-to advice, clarifying terminology and highlighting benefits will help you set the foundation on which to build actionable workflows. Do you find these articles helpful? Please send us your thoughts! And, as always, we are here whenever you want to find out more about Kaizen Analytics.
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CopperTree Analytics
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